1.0 INTRODUCTION AND SUMMARY...

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2 TABLE OF CONTENTS 1.0 INTRODUCTION AND SUMMARY Purpose and Study Objective Executive Summary ROADWAY CONDITIONS Granville Parkway (South Intersection) Tuscany Way (South Intersection) Panther Path Frontage Road/Pav Way TRAFFIC CHARACTERISTICS Data Collection Methodology Corridor Traffic Data Speed Data Turning Movement Volume SAFETY HISTORY Corridor Crash Characteristics Intersection Crash Characteristics TRAFFIC SIGNS TRAFFIC OPERATIONS ANALYSIS Traffic Growth Results Impact of Traffic Movement Prohibitions CONCLUSIONS AND RECOMMENDATIONS Access Management Recommendations at Key Intersections Signing Recommendations Pavement Marking Recommendations Traffic Signal Recommendations APPENDIX A: TRAFFIC DATA 9.0 APPENDIX B: SYNCHRO OUTPUT Existing Conditions AM Existing Conditions PM Rerouted Turning Movements AM Rerouted Turning Movements PM Future Conditions AM Future Conditions PM Rerouted Turning Movements AM Rerouted Turning Movements PM Glassford Hill Road Intersection Safety Study Page ii

3 LIST OF TABLES Table 1: Summary of Traffic Sign Recommendations... 3 Table 2: Glassford Hill Traffic Volume Summary Table 3: Glassford Hill Speed Summary Table 4: Crashes on Glassford Hill Road by Severity Table 5: Crashes on Glassford Hill Road by Month Table 6: Crashes on Glassford Hill Road by Hour of Day Table 7: Crashes on Glassford Hill Road by Type Table 8: Crashes on Glassford Hill Road by Lighting Conditions Table 9: Crashes on Glassford Hill Road by Weather Conditions Table 10: Level of Service Criteria for Signalized/Unsignalized Intersections Table 11: Results of Operational Analysis of 2017 Conditions Table 12: Results of Operational Analysis of 2027 Conditions Table 13: Operational Analysis of Rerouted Left Turns, 2017 Conditions Table 14: Operational Analysis of Rerouted Left Turns, 2027 Conditions LIST OF FIGURES Figure 1: Glassford Hill Road and Four Study Intersections... 7 Figure 2: Granville Parkway (South Intersection)... 8 Figure 3: Tuscany Way (South Intersection)... 9 Figure 4: Panther Path Figure 5: Frontage Road/Pav Way Figure 6: Hourly Traffic Volume on Glassford Hill Rd. North of Santa Fe Loop Figure 7: Hourly Traffic Volume on Glassford Hill Rd. South of Lakeshore Dr Figure 8: Existing Peak-Hour Turning Volumes Figure 9: Glassford Hill Road Crash Heat Map Figure 10: Granville Parkway (South Intersection) Crash Diagram Figure 11: Panther Path Crash Diagram Figure 12: Frontage Road/Pav Way Crash Diagram Figure 13: Typical Median U-Turn Intersection Figure 14: Possible Side-Street Right-Out-Only Configuration Figure 15: Typical Advance Street Name Signs Figure 16: Typical Reduced Speed Ahead Sign Figure 17: Combination No Left Turn/No U-Turn Sign (R3-18) Figure 18: Existing and Recommended R3-8 Sign Approaching SR Figure 19: Lane Reduction Arrow Figure 20: Pavement Marking Recommendation at Granville Parkway (south) Glassford Hill Road Intersection Safety Study Page iii

4 1.0 INTRODUCTION AND SUMMARY 1.1 Purpose and Study Objective Dava & Associates and the Town of Prescott Valley recently engaged Lee Engineering to conduct a traffic study of Glassford Hill Road. The primary objective of the study is to evaluate the following four intersections along Glassford Hill Road and recommend whether to prohibit left-turn movements: Granville Parkway (south intersection) Tuscany Way (south intersection) Panther Path Frontage Road/Pav Way The study includes the following components: Collection of intersection turning movement counts at the four subject intersections, in addition to four nearby intersections Collection of speed data at two locations along Glassford Hill Road Review of the most recent 3-year crash history on Glassford Hill Road generally and at the four subject intersections in particular Creation of an inventory of traffic signs along the entire length of Glassford Hill Road between SR-69 and SR-89A Traffic operational analysis of the subject intersections and nearby intersections to determine the impacts of left-turn prohibitions The results of the study are anticipated to be presented to the public at a meeting in January Executive Summary Data Collection Traffic count and speed data were collected at two locations on Glassford Hill Road: north of Santa Fe Loop and south of Lakeshore Drive. The northern location carries about 2,300 vehicles in the morning peak hour and 2,400 vehicles during the afternoon peak hour. While prominent peaking occurs in the morning and afternoon, the difference in traffic volume by direction is quite small. Total daily volume was recorded as 27,100 vehicles per day (vpd). The southern location carries about 1,800 vehicles during the morning peak hour and 2,200 in the afternoon peak hour. This site shows more diurnal directional differences, but afternoon peak traffic conditions are sustained for about 6 hours, starting about noon and extending until 6:00 p.m. Daily volume is similar to the northern site, 26,300 vpd. Average speed was recorded as 50 mph at the northern site, about 5 mph above the speed limit, and 34 mph at the southern site, just below the 35-mph speed limit. In both cases, 85th percentile speed is about 5 mph higher than average speed. Turning movement volumes were collected at eight locations along the corridor as well. Glassford Hill Road Intersection Safety Study Page 1

5 1.2.2 Safety Crashes were reviewed for the 3-year period between 2014 and A total of 228 crashes occurred on Glassford Hill Road during that time. About 68 percent of the crashes involved only property damage, 32 percent involved at least one injury, and one crash (less than one percent) involved a fatality. Crashes were also reviewed by time of day and year, and with respect to crash type, lighting conditions, and weather conditions. Rear-end crashes account for about half of the crashes on the corridor, not unexpected for a heavilytraveled corridor with frequent signals. Four other crash types had more than a trivial number of crashes: left-turn crashes (16 percent), angle crashes (13 percent), same-direction sideswipe crashes (9 percent), and single-vehicle crashes (8 percent). Among the four study-area intersections: Granville Parkway (south) had the most crashes, 9 in three years, of which 8 involved a left turn. Tuscany Way, already access controlled, experienced no crashes. Panther Path experienced only two crashes in three years, but neither crash involved turning movements. Pav Way had 5 crashes in three years, of which all involved an eastbound or westbound median-crossing maneuver Traffic Signs An inventory was prepared of all signs along the Glassford Hill Road corridor, including the MUTCD code, size, color, and approximate mounting height. The electronic inventory is provided to the Town of Prescott Valley as a separate deliverable. Table 1 presents a summary of the recommendations for improvements to signs on the corridor; further details are provided in a subsequent section. Glassford Hill Road Intersection Safety Study Page 2

6 Table 1: Summary of Traffic Sign Recommendations GPS Coordinates* Sign Latitude Longitude Location inventory Sign type Recommendation Priority number SB, n/o Lakeshore A82 Upgrade panel to Low NB, s/o Lakeshore A86 current MUTCD D3- Low NB, s/o Long Look 260 Advance 2 format (street Low SB, n/o Long Look 233 Street name in upper Low NB, s/o Spouse A27 Name case/lower case Low letters with "NEXT SB, n/o Spouse Point1 SIGNAL" in all caps) Low NB, s/o Santa Fe n/a Medium SB, n/o Santa Fe n/a Medium NB, s/o Granville north n/a Medium SB, n/o Granville n/a Medium north Advance Install new D3-2 sign SB, n/o Sundogs n/a Street Medium and posts NB, s/o Sundogs n/a Name Medium SB, n/o Centre Ct. n/a Medium SB, n/o Sunset/Florentine n/a Medium NB, s/o Sunset/Florentine n/a Medium NB, s/o Centre Ct. n/a Medium Install new W3-5 Speed panel format on SB, n/o Long Look 226 Reduced new posts about Medium Ahead 300 feet upstream of existing Install new R4-7a Median s/o Pav Way n/a Keep Right sign and post for SB traffic on the High median nose Median on Tuscany north n/a NB s/o Spouse NB s/o Panther Path 258 & 259 Keep Right Intersection warning sign Guide sign for middle school Install new R4-7a sign and post for WB traffic on the median nose Remove W2-2 sign and post Relocate sign on new posts 250 to 300 feet upstream of existing High Medium Medium Glassford Hill Road Intersection Safety Study Page 3

7 NB s/o Granville south 195 & NB s/o Long Look 235 Intersection warning sign School zone sign SB s/o Pav Way 120 Lane use NB n/o Pav Way SEC Centre Ct. A SWC Centre Ct. A65 Speed Limit 35 Pedestrian pushbutton NWC Frontage Rd. 39 Delineator Median n/o Sundogs 141 Relocate sign on new posts about 300 feet upstream of existing Remove S1-1 sign and post Replace with modified R3-8 to include U-turn movement if access changes are made at Pav Way Replace worn panel Replace damaged panel Replace damaged panel Remove post and delineator panels Medium Medium Low High High High Low Medium Median s/o Santa Fe 188 Medium Median n/o Santa Fe 190 Remove R3-4 panel Medium No U-turn from reverse of Median s/o Granville 206 existing R4-7 post north Medium Median n/o Granville north 207 Medium Median 800' n/o Lakeshore A79 Medium Median n/o Tuscany south Median n/o Panther Path n/a 263 No Left Turn/No U- Turn Install new R3-18 sign and post for SB traffic Install new R3-18 panel on reverse of existing R4-7 post to prohibit SB U-turns * GPS coordinates are provided for reference and may not depict the exact locations of existing or new signs. High High Traffic Operations Analysis Eight intersections along the corridor were evaluated for their current operational performance, including the four key study intersections and four nearby signalized intersections. Conditions were evaluated for their performance in 2017, using data collected as part of this study, and for performance in future year 2027, assuming a 2 percent annual traffic growth over the next 10 years. Glassford Hill Road Intersection Safety Study Page 4

8 In current conditions, all the evaluated intersections operate at level of service (LOS) D or better during both morning and afternoon peaks. The SR 69 intersection is the most congested of the studied intersections, followed by Long Look Drive. Among the unsignalized intersections, no movements experience a v/c ratio greater than 0.80, which is often used as a threshold of acceptable performance at two-way-stop-controlled intersections. By 2027, all intersections experience increases in delay. The SR 69 intersection is not able to accommodate the assumed increase in traffic volume, and several movements at this intersection fail, most notably in the afternoon peak. The eastbound approach on Frontage Road also exceeds capacity by The remaining intersections continue to operate acceptably overall, although certain traffic movements reach LOS E or F conditions. The prohibition of left-turns was evaluated by rerouting left-turning traffic at the four key intersections along a logical alternative path to a nearby signal. Removing the left turns in all cases improves the operations of the unsignalized intersections and causes slight increases in delay at the nearby signalized intersections Recommendations Following are the study s recommended access management recommendations at the four key studyarea intersections: At Granville Parkway (south), left-turn prohibitions are not recommended. Although the intersection has the most crashes of the study intersections, the crash rate of 2.7 per year is not excessive. The alternative route that motorists would have to use if left turns were prohibited would add significantly to trip distance (1.2 miles) and travel time (3 minutes per trip). Crashes should continue to be monitored to determine if a safety issue develops in the future. At Tuscany Way (south), no changes to access management are recommended; the existing eastbound left-turn prohibition is extremely effective at promoting safety and good operational performance. At Panther Path, no left-turn prohibitions are recommended, because no related crashes have occurred and the intersection operates with high levels of service. At Pav Way, the existing operational performance and future traffic growth suggest that the intersection cannot remain as currently configured in the long term. Median crossings have resulted in 1.7 crashes per year, not excessive, and as such no immediate action is needed. Future prohibition of left-turns and side street through movements would require outreach to affected communities to discuss impacts on surrounding street network; fortunately, the displaced traffic volume is low. Several additional recommendations were made for improvements to traffic signs, pavement markings, and signals in the study area. 2.0 ROADWAY CONDITIONS Glassford Hill Road traverses a mostly north-south alignment in western Prescott Valley, Arizona. It links State Route 69 (SR 69) on the south with State Route 89A (SR 89A) on the north, a length of about 3.6 miles. The street is designated as an arterial roadway by the town of Prescott Valley s Municipal Street Map. Glassford Hill Road Intersection Safety Study Page 5

9 The street extends for a short distance south of SR 69, but the character of this portion of Glassford Hill Road is quite different than the main portion, and it is excluded from the study. Glassford Hill Road is planned to extend north of SR 89A in the future. Glassford Hill Road is median-divided. In general, it carries two through lanes in each direction in the northern portion of the corridor (north of Tuscany Drive) and three lanes in each direction in the south. Some portions of Glassford Hill Road appear to be marked for future bike lanes, because a buffer is provided on the right shoulder and between right-turn bays and through lanes, where bicycle lanes are usually situated. No bicycle lanes are currently designated on the corridor using either signs or pavement markings. This layout of signs and markings is appropriate. Bike lanes normally are not designated until they provide significant length or connectivity to cyclists. Designating short segments of bike lanes can cause less-experienced cyclists to be uncomfortable where bike lanes end abruptly. Ten roadways intersecting Glassford Hill Road are controlled by traffic signals, including one signal at SR 69 and two signals at the interchange with SR 89A. The posted speed limit on Glassford Hill Road is 35 mph in the southern portion of the corridor, south of approximately Long Look Drive, increasing to 45 mph in the northern portion of the corridor. The speed limit for northbound traffic drops to 40 mph just south of the SR 89A interchange. Sidewalks are provided along most of the southern portion of Glassford Hill Road. The west side of the street has a sidewalk from SR 69 to north of Long Look Drive, with a short gap just north of SR 69. The east side of the street has a sidewalk from SR 69 to Florentine Road/Sunset Lane, with a one-block gap just south of Centre Court. Continuous longitudinal sidewalks are not provided in the northern portion of Glassford Hill Road, but all signalized intersections include complete pedestrian accommodations, including curb ramps, sidewalks, pedestrian signal heads, and marked crosswalks. These accommodations appear to be intended for pedestrians crossing Glassford Hill Road, rather than pedestrians walking along the street. The key purpose of this report is to evaluate four unsignalized intersections along Glassford Hill Road to determine whether left-turn prohibitions are recommended due to safety or traffic operational reasons. The four intersections are discussed below from north to south, and shown in Figure 1. Glassford Hill Road Intersection Safety Study Page 6

10 Figure 1: Glassford Hill Road and Four Study Intersections Source: Town of Prescott Valley Glassford Hill Road Intersection Safety Study Page 7

11 2.1 Granville Parkway (South Intersection) Granville Parkway is a loop roadway, intersecting Glassford Hill Road twice in the northern portion of the corridor. The northernmost intersection of Granville Parkway is signalized and is not a key focus of the current study. Rather, the southernmost intersection is a study focus. It is an unsignalized T-intersection with the stem of the T facing east of Glassford Hill Road. Granville Parkway has characteristics common of collector streets. It is undivided with one travel lane in each direction separated by a two-way left-turn lane (TWLTL). It collects and distributes traffic to and from the Granville East subdivision to minimize the amount of traffic on local streets in the neighborhood. Its posted speed limit is 25 mph. The street also provides the primary access to Granville Elementary School from Glassford Hill Road. The intersection of Granville Parkway and Glassford Hill Road is shown in Figure 2. Westbound Granville Parkway splits into two lanes approaching Glassford Hill Road, one each for left and right turns. The length of the two-lane approach is about 100 feet, enough to queue about five vehicles side by side. Northbound Glassford Hill Road has a right-turn bay approaching Granville Parkway; the full-width bay is about 300 feet long plus a taper. Likewise, southbound Glassford Hill Road has a full-width left-turn bay about 130 feet long plus taper. Granville Parkway has a sidewalk on the south side, but the sidewalk stops short of Glassford Hill Road. The intersection itself does not have any designated pedestrian accommodations, either marked crosswalks or sidewalks. Figure 2: Granville Parkway (South Intersection) Source: Google Maps Glassford Hill Road Intersection Safety Study Page 8

12 2.2 Tuscany Way (South Intersection) Like Granville Parkway, Tuscany Way intersects Glassford Hill Road twice. The northernmost intersection of Tuscany Way is the same as the northernmost intersection of Granville Parkway: both streets intersect Glassford Hill Road at the same traffic signal, just south of SR 89A. Tuscany Way is not fully built, but when construction is complete it will traverse about 2 miles south. The southernmost portion of Tuscany Way (south of Santa Fe Loop) is constructed; the northern portion remains under construction. The southern intersection of Tuscany Way and Glassford Hill Road is also a T intersection, with the stem facing west. The southern portion of Tuscany Way shares many characteristics with Granville Parkway. It too carries one through lane in each direction separated by a TWLTL. It too has a posted speed limit of 25 mph. It provides access to the Granville South subdivision, allowing this traffic to enter and exit via either Santa Fe Loop or Glassford Hill Road. Until early 2017, the intersection of Tuscany Way and Glassford Hill Road provided only right-in, right-out access. In 2017, a left-turn lane was constructed on northbound Glassford Hill Road to allow traffic to enter the neighborhood more conveniently from the south. Aerial photography has not yet been updated to depict this left-turn lane. The intersection is shown in Figure 3 with the signing and marking plan for the left-turn lane overlaid on the image to illustrate the current configuration. The new left-turn bay is about 320 feet long, plus taper. Figure 3: Tuscany Way (South Intersection) Image source: Google Maps. Marking plan source: Town of Prescott Valley Glassford Hill Road Intersection Safety Study Page 9

13 Approaching Glassford Hill Road, all traffic on eastbound Tuscany Way is directed to use the right lane, which is designated for right-turns only. The TWLTL stops short of the intersection; rather, the center of the roadway is marked with two sets of double-yellow lines. A sidewalk on the south side of Tuscany Way does not extend as far as Glassford Hill Road; the intersection itself does not have pedestrian accommodations. The terminus of the sidewalk is intended to be consistent with future widening of the southbound lanes of Glassford Hill Road. 2.3 Panther Path Panther Path is not a through street; rather, it provides access to four educational facilities on the west side of Glassford Hill Road: Yavapai College Prescott Valley, Glassford Hill Middle School, Bradshaw Mountain High School, and Lake Valley Elementary School. The name, Panther Path, is taken from the mascot of Glassford Hill Middle School. Panther Path is a two-lane, two-way roadway; a recent project improved the street with curb, gutter, and sidewalks. During our field review we did not identify a posted speed limit sign on Panther Path, but its narrow width, short length, and other characteristics contribute to keep speeds relatively low. Panther Path intersects Glassford Hill Road at a T with the stem facing west. The eastbound approach widens to two approach lanes, one each for left and right turns. Turn bays exist in both directions on Glassford Hill Road to serve traffic turning on Panther Path: a southbound right-turn bay and a northbound left-turn bay, both about 200 feet long plus tapers. Panther Path has more complete pedestrian accommodations than either Granville Parkway or Tuscany Way. A continuous sidewalk on the west side of Glassford Hill Road passes the Panther Path intersection, and a marked crosswalk is provided for pedestrians crossing Panther Path. A sidewalk on the south side of Panther Path connects to the Glassford Hill sidewalk for an uninterrupted pedestrian route. The intersection is not designated as a place for pedestrians to cross Glassford Hill Road by its lack of a marked crosswalk and the lack of a sidewalk on the east side of Glassford Hill Road. However, a signalized pedestrian crossing at Long Look Drive is about 550 feet north of the Panther Path intersection. The intersection is shown in Figure 4. However, while the aerial image is recent, dated June 2017, it still does not reflect current conditions because the project completed later in 2017 is shown in the image as under construction. Glassford Hill Road Intersection Safety Study Page 10

14 Figure 4: Panther Path Image source: Google Maps 2.4 Frontage Road/Pav Way Frontage Road and Pav Way intersect Glassford Hill Road near the southern end of the corridor, less than 500 feet north of SR 69. The west leg of the intersection is named Frontage Road. As the street departs the intersection, it runs in an alignment parallel to SR 69, where it provides access to parcels immediately adjacent to the state highway. The east leg of the intersection, Pav Way, runs about a block north of SR 69 but also provides local access and circulation. Frontage Road is a two-lane, two-way undivided roadway mostly lacking curb, gutter, and sidewalks. Recent developments have added these improvements on the north side of the street adjacent to one parcel near Glassford Hill Road. No posted speed limit sign is evident near Glassford Hill Road, but the horizontal curves are posted with 15-mph advisory speed plates. Pav Way also carries one lane in each direction, but it has a more urban cross-section, with curb, gutter, and sidewalk on both sides of the street. At intersections the through lanes are pushed toward the curbs to make room for left-turn lanes near the center of the road. Pav Way is posted 25 mph. The intersection of Frontage Road/Pav Way and Glassford Hill Road is shown in Figure 5. Left-turn lanes are provided on Glassford Hill Road in both directions; the northbound lane is about 85 feet plus taper and the southbound lane is about 130 feet plus taper. Glassford Hill Road Intersection Safety Study Page 11

15 Complete pedestrian accommodations exist on the east side of Glassford Hill Road, including sidewalks, curb ramps, and a marked crosswalk across Pav Way. No pedestrian accommodations exist on the west side of the intersection, and no accommodations are provided for pedestrians crossing Glassford Hill Road. Figure 5: Frontage Road/Pav Way Image source: Google Maps 3.0 TRAFFIC CHARACTERISTICS 3.1 Data Collection Methodology Traffic data were collected during the week of December 11, 2017, at several locations along the corridor to determine existing traffic volume and speed information along Glassford Hill Road and at key intersections. Traffic data were collected by Traffic Research and Analysis, Inc. (TRA), an Arizona-based firm specializing in traffic data collection. Traffic speed and vehicle classification information were collected on Glassford Hill Road at the following two locations for a 24-hour period: Between Granville Parkway (south intersection) and Santa Fe Loop Between Sundogs Boulevard and Lakeshore Drive These locations were selected to be representative of different conditions in the northern and southern portions of the corridor, and to be consistent with the locations of prior counts to make comparisons more relevant. The speed and count data were collected using radar-based automated Glassford Hill Road Intersection Safety Study Page 12

16 traffic count equipment on a typical weekday. (Data were not collected on Mondays or Fridays.) Turning movement volumes were collected at the following intersections: Granville Parkway/Tuscany Way (north intersection) Granville Parkway (south intersection) Tuscany Way (south intersection) Long Look Drive Panther Path Centre Court Frontage Road/Pav Way SR 69 Turning movement data was collected using video-based equipment designed expressly for collecting traffic volume data. Cameras are set up and aimed at the intersections and traffic movements are recorded, then the resulting video files are later viewed and the turning movements are tabulated. At the three subject intersections where left-turn-out access is currently permitted (Frontage Road/Pav Way, Panther Path, and Granville Parkway), turning movement data were collected and processed for a 13-hour period from 6:00 a.m. to 7:00 p.m. This time period was selected because it almost always encompasses both the morning and evening peak traffic periods, and because peak 8- hour data is sometimes necessary when considering some traffic control devices. At the remaining five intersections, traffic conditions were recorded for an entire 13-hour period in case the data is needed, but turning movement data were processed for a two-hour period in the morning and a two-hour period in the afternoon. The start and end times of the two-hour blocks were selected based on the results of other traffic data to ensure that these two-hour periods include both the morning and afternoon peak periods. 3.2 Corridor Traffic Data Traffic volume on Glassford Hill Road is similar to counts conducted earlier in 2017 and provided by the Town of Prescott Valley. At the northern location between Santa Fe Loop and Granville Parkway (south intersection), we recorded a traffic volume of 27,100 vehicles per day, about 10 percent higher than the earlier count of 24,547 vehicles per day. At this location, hourly volume peaks in both directions in the morning from 7:00 to 8:00 a.m. and in the afternoon from 4:00 to 5:00 p.m., as shown in Figure 6. The afternoon peak has a bit higher traffic volume than the morning peak, and it is somewhat broader as well, with higher volume in the hours surrounding the peak than in the morning. Traffic volume is well balanced on an hourly basis, with both northbound and southbound observing very similar diurnal trends during the day. At this count site, about 93 percent of vehicles were passenger cars or small trucks less than 25 feet long, and the remaining 7 percent of vehicles were longer than 25 feet. Almost all heavy vehicles were between 25 and 55 feet in length; about 0.4 percent of traffic consisted of trucks longer than 55 feet. Glassford Hill Road Intersection Safety Study Page 13

17 Figure 6: Hourly Traffic Volume on Glassford Hill Rd. North of Santa Fe Loop At the southern location between Sundogs Boulevard and Lakeshore Drive, we recorded 26,300 vehicles per day, about 4 percent less than the earlier count of 27,420. When considering both directions, hourly volume peaks at the same times as in the northern count site, 7:00 to 8:00 a.m. and 4:00 to 5:00 p.m., but the peaking characteristics are much different, as shown in Figure 7. Northbound traffic has a slight peak in the morning but a much higher peak in the afternoon, with high volumes for the entire period between noon and 6:00 p.m. Southbound traffic does not have a strong hourly peaking pattern; rather, southbound traffic remains fairly consistent at 1,000 vehicles per hour from 7:00 a.m. to 6:00 p.m. with only minor fluctuations. Vehicle classification at the southern count site was almost identical to the northern site. Just over 7 percent of vehicles were longer than 25 feet, and about 0.4 percent of vehicles were longer than 55 feet. Glassford Hill Road Intersection Safety Study Page 14

18 Figure 7: Hourly Traffic Volume on Glassford Hill Rd. South of Lakeshore Dr. A summary of daily and hourly volume at the two count sites is presented in Table 1, and complete results are included in Appendix A. 3.3 Speed Data Higher speeds were recorded at the northern count site, reflecting the less-developed conditions that contribute to driver comfort at higher speeds. At the north count site, an average speed of 50 mph was recorded, and an 85th percentile speed of 55 mph was recorded. The 85th percentile speed is the speed that 15 percent of vehicles exceed. At this site, 15 percent of vehicles were exceeding 55 mph during the data collection period. Both the average and 85th percentile speeds are greater than the 45-mph speed limit. Overall, average speeds were about 1.5 mph higher in the northbound direction than southbound. No major speed differences were observed during the course of the day. Speeds were slightly lower during high-volume times, but only by about 1 mph. During both morning and afternoon peak hours, average speeds were 49 mph. Glassford Hill Road Intersection Safety Study Page 15

19 Table 2: Glassford Hill Traffic Volume Summary Vehicles per Day Vehicles per Hour, Morning Peak Hour (7:15 to 8:15 a.m.) Vehicles per Hour, Afternoon Peak Hour (4:30 to 5:30 p.m.) North of Santa Fe Loop South of Lakeshore Dr. Northbound 13,530 12,653 Southbound 13,558 13,628 Both Directions 27,088 26,281 Northbound 1, Southbound 1,163 1,063 Both Directions 2,293 1,761 Northbound 1,116 1,208 Southbound 1, Both Directions 2,365 2,180 At the southern count site, speeds averaged 34 mph with an 85th percentile of 40 mph. These speeds are closer to the posted 35-mph speed limit than speeds farther north. Northbound speeds were significantly higher than southbound at this site: an average of 37 mph northbound compared with only 32 mph southbound. This change may be related to the position of the count equipment relative to nearby traffic signals. During the morning peak hour speeds were unchanged from free-flow conditions, but average speeds dropped slightly, to about 33 mph, during the afternoon peak hour. A summary of speed data is presented in Table 2, and complete data is included in Appendix A. Table 3: Glassford Hill Speed Summary Average Speed (mph) 85th Percentile Speed (mph) North of Santa Fe Loop South of Lakeshore Dr. Northbound Southbound Both Directions Northbound Southbound Both Directions Glassford Hill Road Intersection Safety Study Page 16

20 3.4 Turning Movement Volume Peak-hour turning movements were reviewed for the same morning and afternoon peak hours that were identified by reviewing the 24-hour count data on Glassford Hill Road. A summary of peakhour turning movements is presented in Figure 8. Volumes between adjacent intersections were not balanced; rather, raw input volumes were used. In general, the raw volumes were sufficiently similar that no volume balancing was necessary to avoid large sources and sinks between intersections. In most cases, the difference between approach volume at one intersection and departure volume at an adjacent intersection is less than 5 percent. Only in one case did a large balancing issue appear. The traffic count equipment at Tuscany Way malfunctioned after the morning peak period during its original deployment. The traffic count was repeated during the week of December 18, 2017, but the volume between Tuscany Way and Long Look Drive differed more than other intersections because of the difference in data collection day. A complete report of turning movement volume at the eight counted sites is included in Appendix A. Glassford Hill Road Intersection Safety Study Page 17

21 Figure 8: Existing Peak-Hour Turning Volumes approach 1173 departure Glassford Hill Rd. departure approach Granville Pkwy (N) approach departure departure 1188 approach source/sink 3 0% source/sink 20 2% -11-1% -9-1% Glassford Hill Rd Glassford Hill Rd. approach 1191 departure approach Granville Pkwy (S) departure departure 1215 approach approach N 1134 departure AM 1103 PM departure approach Tuscany Way (S) approach departure departure 1216 approach source/sink % source/sink -20-2% 11 2% % Glassford Hill Rd approach N 914 departure AM 1116 PM departure approach Long Look Dr. approach 9 98 departure departure 958 approach approach 962 departure departure approach Panther Path approach 6 9 departure departure 969 approach Glassford Hill Rd approach 784 departure departure approach Centre Ct. approach 38 3 departure departure 755 approach source/sink 0 0% source/sink 7 1% 21 5% -1 0% approach 755 departure Glassford Hill departure approach Pav Wy. approach departure departure 744 approach source/sink 31 4% source/sink 11 2% -2 0% 19 2% approach 775 departure Glassford Hill departure approach SR 69 approach departure departure 201 approach Glassford Hill Road Intersection Safety Study Page 18

22 4.0 SAFETY HISTORY Crashes in the Glassford Hill Road corridor were retrieved from the ADOT Safety Data Mart, a tabulation of historical crashes in Arizona. Crashes in the corridor were identified by relating the Global Positioning System (GPS) coordinates of each crash to the coordinates of the extents of the study corridor. Crashes for the years 2014, 2015, and 2016 were analyzed; this is the most-recent three-year period for which complete crash data are available. 4.1 Corridor Crash Characteristics The crash data revealed a total of 228 crashes on the Glassford Hill corridor in the three-year study period. This total includes crashes at the SR 69 intersection and the ramp termini of the SR 89A interchange. In general, crashes appear to be increasing slightly over the three-year period, as shown in Table 3. It is not always possible to discern long-term safety trends from only three years of crash data, but the overall crash numbers show a steady increase, with nearly 40 percent more crashes in 2016 than in Most crashes on Glassford Hill Road involved only property damage, about 68 percent. About 32 percent of crashes involved at least one injury, and one crash (less than one percent) involved a fatality. The fatal crash occurred on Tuesday, June 14, 2016, at 3:08 p.m. at the intersection of Glassford Hill Road and Centre Court. It was a left-turn crash involving three vehicles. A northbound left-turning vehicle failed to yield to an opposing southbound vehicle; after impact both cars struck a third car stopped and facing eastbound. Killed in the crash was an 86-year-old female in the front passenger seat of the northbound vehicle. Four other people were injured in the crash. Table 4: Crashes on Glassford Hill Road by Severity Severity Total Property Damage Only Injury Fatality Total Crashes were also investigated by month of the year to determine if any seasonal trends affect safety performance. Table 4 presents the month-over-month crash data. While significant variation occurs from one month to the next, the three-year totals by month are more stable. Crashes do appear to drop slightly in late spring and early summer, the months from April through July, when compared to the rest of the year. It is possible that the crash reduction may result from a reduced amount of traffic Glassford Hill Road Intersection Safety Study Page 19

23 during those months, because during some of these months traffic generators such as schools are out of session. Table 5: Crashes on Glassford Hill Road by Month Month Total January February March April May June July August September October November December Total A stronger relationship was observed when investigating crashes by time of day, as shown in Table 5. The hours of the day with the most crashes, 7:00 a.m. and 5:00 p.m., correspond with traditional morning and afternoon peak traffic periods. However, aside from this single hour, crashes in the afternoon hours tended to be higher than in the morning. The seven-hour period from 12:00 noon to 7:00 p.m. experienced at least 15 crashes every hour, but in the morning, no hour other than 7:00 a.m. experienced this many crashes. The seven-hour high-crash afternoon period accounted for 58 percent of crashes in the corridor, though it represents only 29 percent of the day by time. The fact that the high-crash period starts as early as noon suggests that crashes may involve drivers accessing nearby businesses, which tend to be closed during the morning peak but open in the noon hour and in the afternoon peak period. Glassford Hill Road Intersection Safety Study Page 20

24 Table 6: Crashes on Glassford Hill Road by Hour of Day Hour Starting Crashes 12:00 midnight 1 1:00 a.m. 1 2:00 a.m. 1 3:00 a.m. 1 4:00 a.m. 0 5:00 a.m. 3 6:00 a.m. 4 7:00 a.m. 24 8:00 a.m. 9 9:00 a.m :00 a.m. 7 11:00 a.m. 9 12:00 noon 22 1:00 p.m. 17 2:00 p.m. 16 3:00 p.m. 21 4:00 p.m. 18 5:00 p.m. 24 6:00 p.m. 15 7:00 p.m. 6 8:00 p.m. 9 9:00 p.m. 3 10:00 p.m. 5 11:00 p.m. 1 Total 228 Glassford Hill Road Intersection Safety Study Page 21

25 Of critical interest is the type of crashes that occurs on the corridor, because identifying crash countermeasures depends heavily on crash type. Table 6 presents the crash types observed on Glassford Hill Road during the 3-year analysis period. The most common crash type is rear-end collisions, representing about 50 percent of total corridor crashes. Rear-end crashes are common in urban areas where traffic frequently stops because of traffic signals or congestion. Rear-end crashes are among the most difficult to ameliorate using engineering measures because they are almost always caused by a combination of stopped or slow traffic and inattention on the part of a following driver. No other crash type accounted for nearly as many crashes as rear ends, but four other crash types had more than a trivial number of crashes: Left-turn crashes accounted for about 16 percent of total crashes. These crashes are often caused by a driver making a left turn and failing to judge an appropriate gap in oncoming traffic. Angle crashes accounted for 13 percent of the total. Angle crashes are often broadside crashes that result from red-light running or other failure to yield on the part of one or more drivers. Same-direction sideswipe crashes accounted for 9 percent of the total. These are often caused by drivers changing lanes in heavy traffic without an acceptable gap in an adjacent lane. Single-vehicle crashes accounted for 8 percent of the total. These crashes are usually caused when a driver runs off the road and hits a fixed object. They are more prevalent in rural areas but increasingly less common in urban areas. Collectively, these five crash types account for about 96 percent of crashes on the Glassford Hill Road corridor. Notably, no pedestrian or bicycle crashes were recorded. Arizona crash reports also record the lighting and weather conditions in effect when crashes occur. The distribution of lighting conditions on Glassford Hill Road crashes is shown in Table 7, and the distribution of weather conditions is shown in Table 8. Glassford Hill Road Intersection Safety Study Page 22

26 Table 7: Crashes on Glassford Hill Road by Type Crash Type Total Angle Head-On 3 3 Left-Turn Other 1 1 Rear-End Rear to Rear 1 1 Single Vehicle Sideswipe, Opposite dir. Sideswipe, Same dir Unknown 3 3 Total Table 8: Crashes on Glassford Hill Road by Lighting Conditions Lighting Condition Total Dark, lighted Dark, not lighted Dark, unknown lighting Dawn Daylight Dusk Total Glassford Hill Road Intersection Safety Study Page 23

27 Table 9: Crashes on Glassford Hill Road by Weather Conditions Lighting Condition Total Clear Cloudy Fog, Smog 1 1 Rain Snow Total About 76 percent of crashes occurred in daylight, and about 78 percent occurred in clear weather conditions, suggesting that darkness or inclement weather is not a major cause of crashes in the corridor. Of the crashes that occurred during hours of darkness where lighting conditions are known, 71 percent occurred in lit areas of the roadway, reflecting the prevalence of street lights along the heaviest-traveled southern segments of Glassford Hill Road. About 6 percent of crashes occurred in rainy weather and only 1 percent in snow. A heat map of corridor crashes is shown in Figure 9. The heat map identifies locations along the corridor with high concentrations of crashes. The heat map shows that crashes tend to be concentrated at major signalized intersections. The highest-crash locations are in the southern portion of the corridor, at SR 69 and Sunset Lane/Florentine Road. Five other intersections appear as hot spots on the heat map: Lakeshore Drive, Long Look Drive, Spouse Road, Granville Parkway (south intersection), and SR 89A. It should be noted that photo red-light enforcement was conducted prior to the 3-year crash analysis period at Long Look Drive and Spouse Road; the photo enforcement was observed to improve the safety record and motorist compliance with the signal indications. Of these hot spots, only Granville Parkway (south intersection) is among the four key intersections evaluated in the study. The remaining focus intersections do not have high crash numbers relative to the corridor as a whole. Glassford Hill Road Intersection Safety Study Page 24

28 Figure 9: Glassford Hill Road Crash Heat Map Glassford Hill Road Intersection Safety Study Page 25

29 4.2 Intersection Crash Characteristics Crashes at the four key study intersections were evaluated in detail and are discussed below Granville Parkway (South Intersection) A review of the crash data at the south intersection of Glassford Hill Road and Granville Parkway identified a recurring problem with crash coding. Crashes at the subject intersection were identified by their GPS coordinates, and using this method, 19 crashes were located at the subject intersection. However, the Arizona crash report form allows officers to indicate the form of traffic control in place at the time of the crash. In 10 of the 19 crashes, the officer indicated that the intersection was controlled by a traffic signal. Certainly, the subject intersection is unsignalized, and this indicates that these crashes were probably located incorrectly. The most likely explanation is that the crashes occurred at Glassford Hill Road and Granville Parkway (north intersection), which is signalized. The fact that the intersecting streets have the same names is likely a contributing factor. We notified the Arizona Department of Transportation about the crash coding problem so it can be corrected in the future. After eliminating the miscoded crashes, nine crashes were found to have occurred at the subject intersection. (Two additional crashes were coded as having occurred on the Glassford Hill Road approach to the intersection within about 300 feet, but these crashes were determined to be unrelated to the intersection.) On the crash report for one of the nine crashes, the responding officer indicated that the form of traffic control was unknown. As such, it is possible that this crash occurred at Granville Parkway (north intersection), but for the purposes of this analysis we will assume that it occurred at the south intersection. Figure 10 presents a diagram of the nine crashes determined to have occurred at the Granville Parkway south intersection for the 3-year period from 2014 to The nine crashes were composed of the following: Five crashes involved a collision between a westbound left-turning vehicle and a northbound through vehicle. Three of these five crashes involved injury; this crash type was the only one to involve any injuries at the intersection. Three crashes were rear-end crashes involving westbound vehicles approaching the intersection on Granville Parkway. Two of these crashes involved left-turning vehicles and the third involved westbound right-turners. One of these crash reports mentioned sun glare as a contributing factor; this crash occurred slightly before sunset. The other two crashes occurred at other times of day. One crash involved two southbound vehicles, one of which was making a left turn. This crash was coded as a left-turn crash, but it is more likely that it was a rear-end crash or that the crash report had some other coding error. The only crash type that could be considered a recurring pattern is the westbound-northbound collisions. Five crashes of this type in three years works out to an average of 1.7 crashes per year. The crashes at Granville Parkway were not distributed uniformly by year. Seven of the nine crashes occurred in 2015, with only one each in 2014 and It is not known if any unusual conditions in 2015 contributed to the increase in crashes that year, but absent any information to that effect, it is Glassford Hill Road Intersection Safety Study Page 26

30 plausible that the differences in crashes reflects normal random year-to-year variations. Figure 10: Granville Parkway (South Intersection) Crash Diagram Tuscany Way (South Intersection) During the 3-year analysis period, no crashes occurred at the Tuscany Way south intersection. The lack of left-turn access, either inbound or outbound, likely contributes to the outstanding safety record. Only one crash occurred in the vicinity of the intersection, and it was a same-direction sideswipe crash between two southbound vehicles that was determined to be unrelated to the intersection itself. Since no crashes occurred at the intersection, a crash diagram is not presented for Tuscany Way. It is likely that the newly-constructed northbound left-turn lane could change the safety performance of this intersection. The left-turn lane opened in 2017, so crash data from the time the lane was open is not available to be included in this report. The left-turn lane provides new mobility options, but it also adds a conflict point to the intersection that could increase local crashes. (However, vehicles that use this lane may avoid traveling through other nearby intersections and consequently contribute positively to the crash rate elsewhere on the street network.) Glassford Hill Road Intersection Safety Study Page 27

31 4.2.3 Panther Path Two crashes occurred at the intersection of Panther Path and Glassford Hill Road during the 3-year analysis period. Both were rear-end crashes, one in the northbound direction and one southbound, as shown in Figure 11. A third crash occurred about 200 feet north of the intersection and involved a northbound vehicle running off the road, but this crash was determined not to have been intersectionrelated. Neither of the two crashes at the intersection involved any injury. Both cashes occurred in 2016, with no crashes in either 2014 or Remarkably, during the past three years, the Panther Path intersection has experienced no crashes involving left-turning vehicles, neither inbound nor outbound left turns. As with Tuscany Way, Panther Path was under heavy construction in 2017 that changed its geometric characteristics. The work at Panther Path did not change any traffic movements, but it did affect the size of the intersection, and these changes may result in altered safety performance once data begins to arrive following the completion of construction. Figure 11: Panther Path Crash Diagram Glassford Hill Road Intersection Safety Study Page 28

32 4.2.4 Frontage Road/Pav Way The intersection of Frontage Road/Pav Way with Glassford Hill Road experienced five crashes during the 3-year analysis period, an average of 1.7 crashes per year. A sixth crash occurred about 200 feet east of the intersection, but this crash was determined to have occurred where a private driveway intersects Pav Way east of the intersection, and this crash was excluded from the analysis of intersection crashes. All five crashes were of the angle type. Three of the five involved crashes between westbound and southbound vehicles, as shown in Figure 12. The remaining two involved northbound vehicles, one with an eastbound vehicle and the other westbound. The police crash reports indicate that all the vehicles involved in all five crashes were intending to pass straight through the intersection, rather than make a turning movement. Crash reports are not always accurate about drivers intended movements in angle crashes, but if correct, all five crashes involved vehicles traversing across Glassford Hill Road without turning. Frontage Road/Pav Way is the only one of the four focus intersections where through movements across the mainline are permitted, and it appears that through movements account for the only crashes at the intersection. Figure 12: Frontage Road/Pav Way Crash Diagram Glassford Hill Road Intersection Safety Study Page 29

33 Three of the five crashes involved an injury; the other two involved property damage only. The crashes occurred relatively uniformly during the 3-year analysis period. Two crashes occurred each in 2014 and 2016, and one crash occurred in All five crashes occurred in the afternoon, between 12:10 and 5:58 p.m. This period coincides with the highest volume periods on Glassford Hill Road, as noted earlier. While the number of crashes at Pav Way/Frontage Road is modest, the volume of traffic crossing the median is very low, indicating that cross-median traffic is involved in crashes to a disproportionate degree. Six traffic movements at the intersection (left turns from all four approaches plus eastbound and westbound through traffic) are required to cross the median. The remaining six traffic movements (right turns from all four approaches and northbound and southbound through traffic) do not cross the median. The cross-median movements account for 82 vehicles out of a total 1,253 vehicles using the intersection in the morning peak hour, less than 7 percent of the total. In the afternoon peak hour, cross-median movements account for 134 vehicles of a total 1,872, also about 7 percent of the total. Despite accounting for only 7 percent of traffic volume, cross-median movements were involved in 100 percent of crashes during the study period. 5.0 TRAFFIC SIGNS The current study included two elements related to traffic signs, as discussed below. First, an inventory of the traffic signs in the corridor was prepared. The inventory identified the GPS coordinates of each traffic sign on Glassford Hill Road or at cross street intersections, along with the MUTCD code, size, color, and approximate mounting height of each sign. An electronic version of the sign inventory is planned to be delivered to the Town of Prescott Valley independent of the current report. Second, the sign inventory was used to evaluate current signing conditions along Glassford Hill Road and identify possible changes. Recommended signing changes generally fall into two categories: Addition of new signs, where such signs have been shown to provide a benefit to safety or other purposes. The Manual on Uniform Traffic Control Devices (MUTCD) is clear that a sign should fulfill a need. Only in the presence of a documented need are new signs recommended. Removal of existing signs. In some cases, signs tend to remain in place even when the circumstances that justified their installation may have changed in the years since they were installed. Our review determined whether each sign continues to fulfill a need or if it could be removed to reduce overall sign clutter and hence improve the conspicuity of the signs that remain. The study s recommendations on sign improvements are included in Section TRAFFIC OPERATIONS ANALYSIS A traffic operational analysis was conducted in the vicinity of the four key study-area intersections to understand existing traffic operational performance as a baseline for comparing possible future Glassford Hill Road Intersection Safety Study Page 30

34 changes. The Glassford Hill Road intersections included in each area are shown below: Granville Parkway area o Granville Parkway (north intersection)/tuscany Way (north intersection), signalized o Granville Parkway (south intersection), side-street stop-controlled Tuscany Way area o Tuscany Way (south intersection), side-street stop-controlled Panther Path area o Long Look Drive, signalized o Panther Path, side-street stop-controlled Pav Way area o Centre Court, signalized o Pav Way/Frontage Road, side-street stop-controlled o SR 69, signalized For morning and afternoon peak-hour conditions, the intersections were analyzed according to the methodologies in the Highway Capacity Manual 2010 (HCM) using Synchro v9 software. To provide an indication of intersection performance, signalized and unsignalized intersections are typically reported in terms of levels of service (LOS). Signalized intersection analysis is based on average control delay per vehicle, which includes initial deceleration delay, queue move-up time, stopped delay, and final acceleration delay for all movements. Unsignalized stop-controlled intersection analysis is based on the minor street approach or critical movement, whichever is applicable. The HCM level of service criteria for signalized and unsignalized intersection analysis are presented in Table 9. Table 10: Level of Service Criteria for Signalized/Unsignalized Intersections Level of Service (LOS) Average Control Delay (sec/veh) Signalized Unsignalized A B > 10.0 and 20.0 > 10.0 and 15.0 C > 20.0 and 35.0 > 15.0 and 25.0 D > 35.0 and 55.0 > 25.0 and 35.0 E > 55.0 and 80.0 > 35.0 and 50.0 F > 80.0 > 50.0 Source: Exhibits 16-2/17-2, Highway Capacity Manual 2010, Transportation Research Board Glassford Hill Road Intersection Safety Study Page 31

35 The traffic analysis is dependent on signal timing and lane configuration in addition to traffic volume. Lane configurations were collected using recent aerial photography supplemented by field visits due to the recent changes in roadway configuration. Signal timings at the intersection of Glassford Hill Road and SR 69 were provided by the Arizona Department of Transportation (ADOT) since the signal is under ADOT control. Timings at the remaining intersections were provided by Lee Engineering, which manages signal timing for signals under the jurisdiction of the Town of Prescott Valley. Additional performance measures such as volume to capacity (v/c) ratios and queue lengths also provide an indication of operational performance. For example, at two-way STOP-controlled intersections, main street traffic volumes may impose longer average delays for a small number of side-street vehicles, thus creating delays which correspond to a poor level of service. Motorists and agencies will typically accept longer delays (LOS E or F) if gaps in the traffic stream are anticipated within a reasonable timeframe and the side street traffic volumes do not warrant a traffic signal. As a general guide, gap acceptance thresholds for the longer delay values can be defined when the v/c ratios are under 0.80, which corresponds to 80 percent capacity usage for that movement. Therefore, a traffic movement with a v/c value under 0.80 will be considered as operating acceptably even when it has a low LOS. 6.1 Traffic Growth Traffic operational performance was evaluated for current-year conditions, based on volume data collected in December 2017, and this study also evaluates conditions for a future year based on an assumed growth in traffic. The amount of traffic on Glassford Hill Road has increased substantially in recent years. The count sites described in Section 3.2 were selected because the same sites were also counted in a comprehensive 2006 study of the speed limits in Prescott Valley. 1 In 2006, the count side north of Santa Fe Loop carried 19,950 vehicles per day, and this has increased to 27,088 vehicles per day in This reflects a traffic increase of about 36 percent over 11 years, or an average annual traffic growth rate of 2.8 percent per year. Likewise, at the count site south of Lakeshore Drive, traffic volume increased from 23,170 vehicles per day in 2006 to 26,281 vehicles per day in This site shows total traffic growth of about 13 percent, which translates to about 1.2 percent per year. Traffic growth in the northern portion of the corridor is somewhat higher than in the south, likely reflecting the impact of more new development in the north. It should also be noted that the growth rates from 2006 to 2017 occurred despite the impact of an economic recession starting in 2008 that tends to reduce traffic volume. It is unknown whether traffic growth in the future will continue at the same rate as in the past. However, for analysis purposes, it is assumed that traffic will grow at a rate of 2 percent per year, slightly above the average of the rates of increase noted earlier. Over the course of 10 years, a 2 percent annual growth rate works out to total growth of 22 percent. As such, in addition to an evaluation of current conditions, the study also evaluates conditions in the year 2027 by increasing volumes throughout the network by 22 percent to provide an approximation of future traffic growth. 1 Prescott Valley Speed Study, SouthWest Traffic Engineering, LLC, November 28, Glassford Hill Road Intersection Safety Study Page 32

36 In 2027, the signals in the corridor are expected to be retimed to accommodate additional traffic but to maintain their existing cycle lengths for coordination purposes. 6.2 Results Results of the operational analysis are presented in Table 10 for the year 2017 and Table 11 for Glassford Hill Road Intersection Safety Study Page 33

37 Table 11: Results of Operational Analysis of 2017 Conditions AM Delay LOS v/c Queue Delay LOS v/c Queue Delay LOS v/c Queue Delay LOS v/c Queue Granville Pkwy (north) - signalized Intersection 11 B 15 B NBL 11 B A NBL 6 A A EBL 10 B B NBT 11 B B EBR 10 B B NBR 0 A A SBL 6 A A Intersection 6 A 10 B SBT 11 B B NBL 3 A A SBR 0 A A NBTR 5 A A EBL 29 C C SBL 2 A A EBTR 0 A B SBTR 5 A A WBL 31 C C EBL 56 E F WBTR 1 A B EBTR 24 C B Granville Pkwy (south) - unsignalized WBL 56 E E SBL 12 B B WBTR 24 C D WBL 34 D D WBR 14 B B NBL 9 A A Tuscany Way (south) - unsignalized SBL 9 A B NBL 12 B B EBLTR 23 C F EBR 17 C C WBL 21 C F Long Look Dr. - signalized Intersection 33 C 15 B PM Panther Path - unsignalized Centre Ct. - signalized Pav Way - unsignalized WBTR 15 C C SR 69 - signalized NBL 56 E E Intersection 38 D 52 D NBT 20 C B NBL 64 E E NBR 0 A A NBTR 26 C D SBL 107 F E SBL 71 E E SBT 27 C A SBT 35 C D SBR 4 A A SBR 18 B C EBL 74 E E EBL 70 E E EBT 52 D E EBT 30 C D EBR 15 B A EBR 0 A A WBL 72 E E WBL 71 E F WBT 60 E D WBT 42 D D WBR 1 A A WBR 4 A A Notes: Delay is measured in seconds per vehicle. Queue refers to the 95th percentile queue length in feet. The HCM does not define a methodology to compute intersection LOS at stop-controlled intersections. Glassford Hill Road is desingated as the NB/SB route at all cross-street intersections. At unsignalized intersections, mainline through movements have very little delay and are not shown. Highlighted movements have LOS E or F, unless (for unsignalized intersections), v/c < AM PM Glassford Hill Road Intersection Safety Study Page 34

38 Table 12: Results of Operational Analysis of 2027 Conditions AM PM AM Delay LOS v/c Queue Delay LOS v/c Queue Delay LOS v/c Queue Delay LOS v/c Queue Granville Pkwy (north) - signalized Intersection 14 B 14 B NBL 13 B B NBL 6 A A EBL 11 B B NBT 13 B B EBR 11 B B NBR 0 A A SBL 6 A B Intersection 6 A 13 B SBT 13 B B NBL 3 A B SBR 0 A A NBTR 5 A A EBL 35 C C SBL 3 A A EBTR 0 A B SBTR 5 A B WBL 42 D D EBL 56 E F WBTR 4 A B EBTR 22 C B Granville Pkwy (south) - unsignalized WBL 55 E E SBL 14 B B WBTR 23 C D WBL 63 F F WBR 16 B B NBL 10 A A Tuscany Way (south) - unsignalized SBL 9 A B NBL 14 B C EBLTR 33 D F EBR 26 D C WBL 28 D F Long Look Dr. - signalized Intersection 44 D 17 B Panther Path - unsignalized Centre Ct. - signalized Pav Way - unsignalized WBTR 20 C D SR 69 - signalized NBL 53 D E Intersection 45 D 88 F NBT 23 C B NBL 66 E E NBR 0 A A NBTR 27 C D SBL 148 F E SBL 71 E E SBT 33 C B SBT 38 C D SBR 4 A A SBR 25 C C EBL 107 F E EBL 83 F F EBT 48 D E EBT 32 C F EBR 20 B A EBR 0 A A WBL 184 F E WBL 74 E F WBT 59 E D WBT 53 D E WBR 2 A A WBR 4 A A Notes: Delay is measured in seconds per vehicle. Queue refers to the 95th percentile queue length in feet. The HCM does not define a methodology to compute intersection LOS at stop-controlled intersections. Glassford Hill Road is desingated as the NB/SB route at all cross-street intersections. At unsignalized intersections, mainline through movements have very little delay and are not shown. Highlighted movements have LOS E or F, unless (for unsignalized intersections), v/c < PM In existing conditions, all four unsignalized intersections experience relatively good operational performance during peak periods, with most movements at LOS C or better. At Granville Parkway Glassford Hill Road Intersection Safety Study Page 35

39 (south), the westbound left-turn movement operates at LOS D, but delays and queues are manageable and the intersection is well below capacity. The only possible unsignalized operational problem occurs at Pav Way, where the eastbound and westbound approaches experience LOS F conditions during the afternoon peak period. Eastbound experiences a larger problem than westbound, with delays nearly 100 seconds and v/c ratio at 0.74, just slightly below the 0.80 threshold discussed earlier. However, queues are satisfactory on both approaches. It is likely that the long delays during peak periods already causes some drivers to avoid these approaches where viable alternatives exist. Among the signalized intersections, Granville Parkway (north) and Centre Court operate with overall LOS A and B conditions and few operational problems. At Centre Court, the eastbound and westbound left-turn movements experience disproportionately high delay when compared to other movements at the intersection. The intersection of Long Look Drive has good service levels overall, LOS C in the morning and LOS B in the afternoon, but left-turn movements reach LOS E or F conditions in all four directions. Morning peak conditions are slightly worse than afternoon conditions. SR 69 is the most congested of the study-area intersections, with LOS D conditions overall in both morning and afternoon periods. The intersection s worst movements are also left turns; all four left turns at the intersection operate LOS E or F during both peak periods. Unlike Long Look Drive, SR 69 has higher intersection delay during the afternoon than in the morning. The additional traffic assumed by 2027 causes delays to increase at all study intersections. At Granville Parkway, the westbound left turn movement is expected to operate with LOS F but has a v/c ratio less than 0.8, so it is considered satisfactory. Tuscany Way and Panther Path are expected to have no operational problems. At Pav Way, the additional traffic is expected to cause the eastbound approach to exceed capacity. Its v/c ratio is forecast to reach 1.32, an indication of a severe traffic overload. The westbound approach is better, with a v/c ratio of 0.66, but it too has uncomfortably long delays that could lead to risky decision making by drivers. Granville Parkway (north) and Centre Court remain overall LOS A and B intersections by 2027, but the eastbound left-turn is expected to operate at LOS F at Centre Court. Long Look Drive drops to LOS D in the morning peak by 2027 with considerable problems on left-turn movements: three of the four left turns drop to LOS F in the morning peak. The SR 69 intersection fails in the afternoon; it is not able to accommodate the 22 percent increase in traffic forecast by The major effects of this overload are observed on eastbound and westbound approaches, where LOS reaches F for at least one movement and v/c nears or exceeds 1.0. It is likely that major infrastructure improvements would be needed to accommodate this increase in traffic at the SR 69 intersection. 6.3 Impact of Traffic Movement Prohibitions It has been suggested that left turns (and through traffic, where applicable) might be prohibited to, from, and/or across Glassford Hill Road at the four key study-area intersections in an effort to improve safety. While safety is likely to be improved, the change would require traffic to find new routes to avoid the movements suggested for elimination. The traffic operational analysis of the prohibitions were evaluated using the following assumed rerouting behavior: Glassford Hill Road Intersection Safety Study Page 36

40 At Granville Parkway (south intersection), it is assumed that both southbound and westbound left turns would reroute to Granville Parkway (north intersection). This route relies on Granville Parkway, and some residents may find an increase in traffic on Granville Parkway to be undesirable. However, no other logical alternative routes are available for use in the event of a left-turn prohibition. At Tuscany Way, eastbound left turns are already prohibited, and northbound left turns were provided recently, in 2017, as part of a capital construction project. As such, no change to access control is assumed at Tuscany Way. At Panther Path, it is assumed that eastbound and northbound left turns would reroute to Long Look Drive. This route would make use of existing on-site connecting roadways within the school campuses on the west side of Glassford Hill Road. The rerouting to Long Look Drive appears to be the most direct alternative route available for displaced left turns. However, it should be noted that the internal site roadways are not public streets, and they are currently closed to traffic at some times of day. At Pav Way/Frontage Road: o Westbound and southbound left turns are assumed to be rerouted to Centre Court. These trips originate either to or from the east/south side of Glassford Hill Road, and the interconnectivity of Pav Way and Centre Court makes this rerouting the shortest possible trip. o Eastbound left turns are assumed to reroute by turning right onto southbound Glassford Hill Road, then making a U-turn at SR 69. This route is potentially difficult because of the large number of lanes to cross on southbound SR 69, but the lack of connectivity on the west side of Glassford Hill Road complicates the alternative routing. Another option would involve using local streets (such as Pleasant View Drive) to Sunset Lane to rejoin Glassford Hill Road, but this route may be undesirable because of its impact on front-facing residential properties. o Northbound left turns are assumed to reroute by using westbound SR 69 to the next intersection, Valley View Drive. The specific impacts of the displaced traffic on Valley View Drive at Frontage Road was not evaluated in detail because of uncertainty about drivers travel paths so far from the Glassford Hill corridor. However, the volume of displaced traffic is so small that the impacts are expected to be insignificant. o The Pav Way/Frontage Road intersection is the only one of the four key study intersections that permits through traffic across Glassford Hill Road. It is assumed that eastbound and westbound through traffic would divert using the same general routing as eastbound and westbound left turns, respectively. In all cases, it is recognized that drivers may need some time to acclimate to traffic patterns if left turns are prohibited, and during the acclimatization process, the rerouting may be different than described above. However, for the purpose of the traffic operational analysis, it is assumed that drivers have already become accustomed to the changes in the roadway network and are using a route that is the most efficient for their trip. Using the above assumptions, the traffic operational impact of the turn prohibitions was evaluated, and the results are reported in Table 12 for 2017 conditions and Table 13 for Glassford Hill Road Intersection Safety Study Page 37

41 As expected, removing the left turns from the unsignalized intersections would improve their operational performance. All three intersections where a change in access is assumed would experience a reduction in delay. However, the change is minimal at Panther Path since the intersection operates well in existing conditions. All four unsignalized intersections are expected to operate at LOS C or better even into 2027, with the exception of the eastbound right-turn movement at Tuscany Way, which has delay of 26 seconds, just above the threshold for LOS D. The nearby signalized intersections absorb traffic diverted from the unsignalized intersections, and the additional traffic causes slight increases in delay for a few movements and a considerable change for a few others. Granville Parkway (north) and Centre Court are equipped to handle the increase in traffic and continue to operate satisfactorily. At Long Look Drive, the access change increases overall delay by 2 seconds in the morning peak in 2017 and 5 seconds by Most drivers are unlikely to notice an increase in average delay as small as 2 seconds, but a 5-second increase could be noticeable. At Long Look, the largest effects of the access change are borne by the left-turn movements, which already are among the worst performing at the intersection. The eastbound and westbound left turns are among the movements with greater than average increases in delay. The additional delay amounts to a few seconds in 2017, but increases to over 30 seconds by 2027 as more demands are placed on the intersection s limited green time. SR 69 shows an overall increase in delay of only 1 second in 2017, with the biggest impact on the southbound left turn, with an additional 8 seconds delay. Similar changes carry forward in 2027, but by then the intersection is so far over capacity that the analysis is of limited utility. Glassford Hill Road Intersection Safety Study Page 38

42 Table 13: Operational Analysis of Rerouted Left Turns, 2017 Conditions Delay LOS v/c Queue Delay LOS v/c Queue Delay LOS v/c Queue Delay LOS v/c Queue Intersection 14 B 16 B NBL NBL 6 A A EBL NBT 16 B B EBR 9 A A NBR 0 A A SBL 7 A B Intersection 7 A 11 B SBT 12 B B NBL 3 A A SBR 0 A A NBTR 5 A A EBL 30 C C SBL 3 A A EBTR 0 A B SBTR 5 A A WBL 42 D C EBL 56 E F WBTR 1 A B EBTR 24 C B WBL 60 E E SBL n/a n/a WBTR 24 C D WBL AM PM AM Granville Pkwy (north) - signalized Granville Pkwy (south) - unsignalized n/a WBR 14 B B NBL Tuscany Way (south) - unsignalized NBL 12 B B EBR 10 B B EBR 17 C C WBL Long Look Dr. - signalized Intersection 35 D 15 B n/a SBL Panther Path - unsignalized WBR 10 B B NBL 51 D E Intersection 39 D 53 D NBT 20 B B NBL 64 E E NBR 0 A A NBTR 26 C D SBL 107 F E SBL 74 E E SBT 32 C A SBT 35 C D SBR 4 A A SBR 18 B B EBL 77 E E EBL 70 E E EBT 51 D E EBT 30 C D EBR 15 B A EBR 0 A A WBL 76 E E WBL 71 E F WBT 60 E E WBT 43 D D WBR 1 A A WBR 4 A A Notes: Delay is measured in seconds per vehicle. Queue refers to the 95th percentile queue length in feet. The HCM does not define a methodology to compute intersection LOS at stop-controlled intersections. Glassford Hill Road is desingated as the NB/SB route at all cross-street intersections. At unsignalized intersections, mainline through movements have very little delay and are not shown. Highlighted movements have LOS E or F, unless (for unsignalized intersections) v/c < n/a n/a Centre Ct. - signalized Pav Way - unsignalized n/a n/a n/a SR 69 - signalized PM n/a n/a n/a n/a n/a Glassford Hill Road Intersection Safety Study Page 39

43 Table 14: Operational Analysis of Rerouted Left Turns, 2027 Conditions Delay LOS v/c Queue Delay LOS v/c Queue Delay LOS v/c Queue Delay LOS v/c Queue Intersection 16 B 17 B NBL NBL 6 A A EBL NBT 14 B B EBR 10 A A NBR 0 A A SBL 8 A B Intersection 7 A 15 B SBT 12 B B NBL 3 A A SBR 0 A A NBTR 5 A A EBL 35 C C SBL 3 A A EBTR 0 A B SBTR 5 A A WBL 71 E E EBL 56 E F WBTR 4 A B EBTR 22 C B WBL 61 E E SBL n/a n/a WBTR 23 C D WBL WBR 16 C B NBL Tuscany Way (south) - unsignalized SBL n/a n/a NBL 14 B C EBR 10 B B EBR 26 D C WBL Intersection 49 D AM PM AM Granville Pkwy (north) - signalized Granville Pkwy (south) - unsignalized Long Look Dr. - signalized Panther Path - unsignalized n/a n/a Pav Way - unsignalized WBR 11 B B NBL 50 D E Intersection 47 D 89 F NBT 23 C B NBL 66 E E NBR 0 A A NBTR 28 C D SBL 148 F E SBL 71 E E SBT 38 D B SBT 38 D D SBR 5 A A SBR 25 C C EBL 145 F E EBL 83 F F EBT 48 D E EBT 32 C F EBR 20 B A EBR 0 A A WBL 220 F E WBL 74 E F WBT 59 E E WBT 56 E E WBR 2 A A WBR 3 A A Notes: Delay is measured in seconds per vehicle. Queue refers to the 95th percentile queue length in feet. The HCM does not define a methodology to compute intersection LOS at stop-controlled intersections. Glassford Hill Road is desingated as the NB/SB route at all cross-street intersections. At unsignalized intersections, mainline through movements have very little delay and are not shown. Highlighted movements have LOS E or F, unless (for unsignalized intersections) v/c < n/a n/a Centre Ct. - signalized n/a n/a SR 69 - signalized PM n/a n/a n/a n/a Glassford Hill Road Intersection Safety Study Page 40

44 7.0 CONCLUSIONS AND RECOMMENDATIONS The following recommendations should be considered: 7.1 Access Management Recommendations at Key Intersections Granville Parkway (South Intersection) Operationally, the south intersection of Granville Parkway and Glassford Hill Road is acceptable, if not ideal. The movement with the most delay is the westbound left turn, and in 2017 it operates at LOS D during morning and afternoon conditions. In both cases, average delay is just over 30 seconds and v/c is between 0.30 and These operational conditions are tolerable during peak hours. By 2027, this movement could reach LOS F with v/c ratios of 0.50 to Two factors make this operational result less of a concern than it might appear. First, the assumed 22 percent traffic growth by 2027 was applied to all movements at every intersection, but the westbound movement at Granville Parkway is unlikely to experience this much growth since the subdivision is built out. Growth on Glassford Hill Road will likely make left turns out of the side street more difficult, but likely not to the extent shown. Second, as noted earlier, the Highway Capacity Manual (HCM) methodology for unsignalized intersections often produces delay values greater than observed in the field. A key reason is that the methodology does not account for the effects of nearby traffic signals, which create gaps in traffic to a greater degree than would be seen with traffic arriving randomly. It is very common to observe field conditions operating better than the HCM predicts. Since the Granville Parkway movements operate with v/c ratios less than 0.80, they are not likely to be operationally degraded. Based on the operational analysis, traffic operational performance is not a reason on its own to prohibit turns at the intersection. The intersection s safety record for the past three years shows an average of 2.7 crashes per year that involve a left-turning vehicle, and about a third of these were rear-end crashes that occurred upstream of the median-crossing. While this is not a perfect safety record, a rate of 2.7 crashes per year appears to be below the threshold at which a severe action such as median closure is indicated. For example, the MUTCD includes a threshold of 5 related crashes per year when considering whether to install a traffic signal under the crash warrant. The safety record clearly shows that the westbound left-turn movement is involved in more crashes than the southbound lefts. This is not unexpected, since drivers making a westbound left must contend with traffic approaching on Glassford Hill in both directions. While the operational analysis shows that left turns from Granville (south) could be absorbed by Granville (north), the prohibition of westbound left turns would cause a large increase in trip length and travel time for diverted trips. Drivers at the intersection of Voltaire Drive and Granville Parkway would see an increase in their trip length of about 1.2 miles to divert to Granville Parkway (north), and this is likely to require additional travel time of about 3 minutes per trip assuming travel Glassford Hill Road Intersection Safety Study Page 41

45 at the speed limit. This additional trip length and travel time is about the maximum that could be experienced by any drivers, but it is instructive because these trips would be experienced by drivers departing from Granville Elementary School and destined for points south. A long increase in trip length and a 3-minute increase in travel time generally run counter to goals of providing a transportation network that is as efficient as possible, and it is likely that motorists would object to the changes for this reason. The southbound lefts could be diverted to Granville (north) without as much additional trip length or travel time, but this is also the left-turn movement least necessary to prohibit because of its safety record. Considering the safety, operational, and travel time implications, it is not recommended that any left turn prohibitions be made at Granville Parkway (south) at this time. It is recommended that the safety performance of this intersection be monitored in the future to determine if a significant increase in crashes occurs that could justify reconsideration of this recommendation. If crashes increase in the future or if it is determined that left-turn prohibitions are indicated now, the following elements should be considered: The westbound left-turn movement should be a higher priority to prohibit than the southbound left, based on its much higher involvement in crashes. If the westbound left turn is prohibited, it may be desirable to consider constructing a median U-turn between Granville Parkway (south) and Granville Parkway (north) to reduce the increase in trip length and travel time. A diagrammatic sketch of a median U-turn is shown in Figure 13. Such a configuration has been estimated to reduce crashes by 25 to 50 percent Tuscany Way (South Intersection) Tuscany Way is a model for outstanding access management in the Glassford Hill Road corridor. Historically it has provided no left-turn access, either in or out, but a change in 2017 allowed northbound left turns into Tuscany Way. As discussed earlier, this movement is usually involved in fewer crashes than lefts out. No crashes occurred at Tuscany Way in the 3-year study period, but it is possible that this perfect record will change with the provision of the northbound lefts. The intersection operates with excellent levels of service in both current and future conditions. The only movement currently prohibited, the eastbound left turn, does not experience an undue increase in travel time or trip length because the diversion route along Tuscany Way and Santa Fe Loop Road is largely in the desired direction of travel. No changes to traffic movements are recommended at Tuscany Way. 2 Median U-turn Intersection Tech Brief, Federal Highway Administration Publication FHWA-HRT , October Glassford Hill Road Intersection Safety Study Page 42

46 Figure 13: Typical Median U-Turn Intersection Source: FHWA-HRT Panther Path Of the four study area intersections, Panther Path has the best operational characteristics: all of its movements operate at LOS B or better in both AM and PM, even in The provision of left turns at this intersection does not degrade operations, and hence it would not be appropriate to prohibit left turns for operational reasons. Likewise, Panther Path has an outstanding safety record. While two crashes occurred at the intersection over the 3-year study period, neither involved a left-turning vehicle. The operational study found that if left turns were prohibited, they could be diverted to nearby Long Look Drive without a significant change in delay, but Long Look is a more congested intersection than some on the corridor, and adding traffic to the Long Look intersection would contribute to a minor degradation of its performance. If it is determined that left turns should be prohibited at Panther Path, the increase in trip length and travel time is small because of the proximity of Panther Path and Long Look. The northbound leftturn movement would have the larger impact, but even this movement would experience added trip length of only about 0.2 mile. In any case, because of the excellent safety record and satisfactory operations, it is recommended that no turn prohibitions be implemented at Panther Path. Glassford Hill Road Intersection Safety Study Page 43

47 7.1.4 Pav Way/Frontage Road Pav Way is the most operationally challenging of the four key study intersections. It is only about 400 feet from the major signalized intersection at SR 69, and it currently allows all movements lefts, throughs, and rights from both side street approaches. The eastbound and westbound approaches both operate at LOS F today, and the eastbound approach has a v/c ratio of 0.74, very near the 0.80 threshold that signifies a severe operational issue. Considering the growth in traffic on the Glassford Hill Road corridor, it is expected the 0.80 threshold will be exceeded soon. High delays sometimes lead to safety problems, because drivers take risks when seeking gaps in approaching traffic. The Pav Way intersection experienced only five crashes in the past 3-year period, an average of 1.7 crashes per year. Four of the five involved eastbound motorists. No crashes involved northbound or southbound left-turning vehicles. However, the number of crashes involving side-street left turns and through traffic is somewhat more concerning considering the low volume of side-street traffic. During the 13-hour count period from 6:00 a.m. to 7:00 p.m., the highest-volume of the side-street cross-median movements carried less than 300 vehicles. (By comparison, Glassford Hill Road carried over 19,000 vehicles during this same 13-hour period.) The low volume translates to a higher crash rate for side-street cross-median movements. If westbound left turns and through traffic were prohibited, the alternative route along Pav Way and Centre Court would increase trip lengths by about 0.4 mile at the most. This trip could require less than 1 minute of additional travel time during off-peak periods, but it passes through two signals on Centre Court, at both Pav Way and Glassford Hill Road, so the travel time is dependent on operational conditions at these intersections. The diversion route for eastbound traffic is not ideal. The route assumed in the operational analysis would add U-turn traffic to southbound Glassford Hill Road approaching SR 69, already a heavily congested intersection. This movement would also require diverted traffic to reach the left-most lane on southbound Glassford Hill Road, which could be a challenging merging movement during heavy traffic periods. Alternatively, eastbound traffic could divert to a network of local streets north of Frontage Road, such as Valley View Drive, Mountain View Drive, Lynx Lane Drive, and Pleasant View Drive, to reach Sunset Lane. All of these local streets have front-facing homes, and residents may be displeased to absorb traffic diverted away from the Pav Way intersection. This potential intrusion onto the local street network is mitigated by the low volume of diverted traffic about 50 vehicles per hour in the afternoon peak. Because of the traffic operational characteristics, the expected future growth in traffic, and the proximity of the intersection to SR 69, we observe that the intersection as currently configured is not likely to be sustainable in the long term. While the current safety performance is acceptable, it is likely that crashes will increase with traffic volume in the future. The acceptable safety performance means that no immediate action needs to be taken at the intersection, but it is recommended that the Town consider how this intersection should be Glassford Hill Road Intersection Safety Study Page 44

48 reconfigured in the long term to support the efficient flow on Glassford Hill Road so close to a major state highway. One option to consider would be to prohibit eastbound and westbound left turns and through movements, but continue to allow northbound and southbound left turns. The northbound and southbound lefts have excellent safety records, and retaining these movements reduces the amount of traffic that would need to divert to alternative routes. A sketch showing one way to accomplish this turn prohibition using a raised island is shown in Figure 14. If community concerns arise about the prohibitions at Pav Way, it would be possible to install the prohibitions on a temporary basis. During the temporary installation, traffic volumes and speeds could be collected on logical diversion routes to better understand drivers revised travel patterns. Figure 14: Possible Side-Street Right-Out-Only Configuration Image source: Google Maps Glassford Hill Road Intersection Safety Study Page 45

49 7.2 Signing Recommendations Advance Street Name Signs Advance street name signs, as shown in Figure 15, indicate to drivers the name of the street at an upcoming intersection. Advance street name signs are useful to unfamiliar drivers on multilane roadways because they allow drivers to begin to position themselves in the correct lane well in advance of a turn. A 2009 study of advance street name signs 3 showed that while such signs only reduced total crashes by about 2 percent, they reduced same-direction sideswipe crashes by over 10 percent. Same-direction sideswipe crashes are likely to occur when drivers make sudden lane changes, and it is logical that the additional information provided by advance street name signs can help reduce these crashes. Same-direction sideswipes are not one of the most common on the Glassford Hill corridor, but it did experience 21 such crashes in the past 3-year period. The need for advance street name signs increases as a street is widened, because motorists are required to execute more lane changes to make a desired turn. Advance street name signs are used upstream of signalized intersections and major unsignalized intersections. They can be installed either in the median or the right-hand side of the roadway, but a consistent approach to locating and designing such signs can help motorists know where to expect them as they traverse the corridor. Our review of Glassford Hill Road showed that many intersections are already equipped with advance street name signs. These include Lakeshore Drive, Long Look Drive, and Spouse Drive, in both directions. The existing signs do not have high target value because they are somewhat small, and the legend includes only the name of the street without the explanatory text NEXT SIGNAL as shown on the sign in the lower left corner of Figure 15. It would be possible to upgrade the existing signs to be larger and more conspicuous, but a higher priority should be installing advance street name signs approaching signals where they do not currently exist: Centre Court, Sunset Lane/Florentine Lane, Sundogs Boulevard, Santa Fe Loop, and Granville Parkway/Tuscany Way (north intersection). 3 Safety Evaluation of Advance Street Name Signs, Federal Highway Administration Publication FHWA-HRT , June Glassford Hill Road Intersection Safety Study Page 46

50 Figure 15: Typical Advance Street Name Signs Source: MUTCD Figure 2D Speed Limit and Associated Signs Speed limit signs appear to be well positioned in the corridor. They tend to be appropriately located downstream of most signalized intersections and clearly communicate the speed limit. On southbound Glassford Hill Road is a warning sign, SPEED REDUCED AHEAD, approaching Long Look Drive. It is recommended that this sign be replaced with a new panel using the current MUTCD format, as shown in Figure 16 (but referring to a 35 mph speed limit). The new sign design gives drivers more information because it reinforces the new speed limit, rather than merely the need for a speed reduction. It is also recommended that this sign be relocated further upstream. The reduced speed ahead sign and the speed limit sign are currently about 200 feet apart. This distance is adequate according to the MUTCD, but it is so close that it does not allow motorists to make a gradual, coasting transition to the slower speed. Since there is ample distance to the next upstream intersection, it is recommended that the reduced speed ahead sign be positioned about 500 feet upstream of the speed limit sign. Figure 16: Typical Reduced Speed Ahead Sign Glassford Hill Road Intersection Safety Study Page 47

51 Source: MUTCD Figure 2C Keep Right Signs Many jurisdictions report that Keep Right symbolic signs (R4-7A) are among the most frequently knocked down by errant motorists because of their location on median noses. However, these signs provide vital information to both mainline drivers and drivers turning left onto the mainline from a cross street, to give them information about the correct portion of the roadway to use. We observed the following median noses without Keep Right signs, and it is recommended that such signs be installed at these locations: Pav Way, south leg Tuscany Way (north intersection), west leg U-Turn Signs Several intersections along Glassford Hill Road are posted with No U-Turn signs. If these signs were installed to address a problem, they should certainly remain. However, the raised median by its nature prohibits left turns to and from some points of access along the corridor, creating a demand for U-turns. It is recommended that U-turn prohibitions should be evaluated to determine if U-turn restrictions could be safely lifted. Our review of the corridor identified the following U-turn prohibitions as potential candidates for removal: Sundogs Boulevard, southbound Santa Fe Loop Road, northbound and southbound Granville Parkway (north)/tuscany Way (north), northbound and southbound Median break about 800 feet north of Lakeshore Drive, southbound Two intersections along the corridor are configured for left turns in one direction only, and in the opposite direction left turn bays are not provided. At these two locations, it is recommended that signing be installed in the median to alert motorists that these turns are prohibited. Separate signs for no left turn and no U-turn could be installed on the same post, or a combination no left-turn/no U- turn sign, as shown in Figure 17, could be used. The two locations are as follows: Tuscany Way (south), southbound left turns or U-turns. Panther Path, southbound left turns or U-turns Glassford Hill Road Intersection Safety Study Page 48

52 Figure 17: Combination No Left Turn/No U-Turn Sign (R3-18) Other Signs An intersection warning sign (W2-2) is in place approaching Spouse Drive northbound. Signs of this nature are not usually used approaching signalized intersections, because it is more appropriate to warn drivers about the presence of the signal. At Spouse Drive, motorists have a clear view of the signal indications, and it does not appear that conditions at this intersection are so different from others that a warning sign is needed at all. It is recommended that the W2-2 sign be removed. A guide sign is in place for Glassford Hill Middle School on northbound Glassford Hill Road approaching Panther Path. However, this sign is much too close to the point of the turn to be useful to unfamiliar motorists. The sign should be moved upstream by 250 to 300 feet so motorists can see it in time to react and enter the left-turn bay. Likewise, an intersection warning sign (W2-2) is in place on northbound Glassford Hill Road approaching Granville Parkway (south intersection), but it also is too close to the intersection. It should be positioned prior to the start of the taper for the right-turn bay, about 200 to 300 feet upstream of its current location. Two school-zone warning signs (S1-1) are in place on northbound Glassford Hill Road approaching Long Look Drive. In general, one such sign is sufficient to alert motorists of the presence of school activity. It is recommended to retain the first existing sign and remove the second (furthest north) sign, closest to Long Look Drive. A median-mounted lane configuration sign (R3-8) is in place on southbound Glassford Hill Road approaching SR 69. This sign indicates that both left lanes can be used to make left turns. While this sign reflects the correct lane configuration, if access changes are implemented at Pav Way/Frontage Road, it may be desirable to update this sign to show that U-turns are permitted only from the left-most lane, since the access change is expected to increase the demand for U-turns. Existing and recommended signs are shown in Figure 18. Glassford Hill Road Intersection Safety Study Page 49

53 The following sign panels are recommended to be replaced because of excessive wear or impact: o The speed limit sign on northbound Glassford Hill Road north of Pav Way should be replaced due to wear. o Pedestrian pushbutton signs on the southeast and southwest corners of Glassford Hill Road and Centre Court should be replaced due to impact. A delineator on the northwest corner of Glassford Hill Road and Frontage Road is recommended to be removed, since its purpose could not be determined. Figure 18: Existing and Recommended R3-8 Sign Approaching SR Pavement Marking Recommendations Image source: Google Earth Where the third lane on northbound Glassford Hill Road drops north of Long Look Drive, it is recommended that two pavement lane reduction arrows, as shown in Figure 19, be installed in the dropping lane in advance of the drop to reinforce the message on the lane drop warning signs. Glassford Hill Road Intersection Safety Study Page 50

54 Figure 19: Lane Reduction Arrow Source: MUTCD Figure 3B-24 (F) On westbound Florentine Road approaching Glassford Hill Road, the right-most lane drops as a right-turn only lane onto northbound Glassford Hill Road. In drop-lane situations such as this, the markings between the dropped lane and the adjacent through lane should be wide dotted markings, not the normal-width broken lane lines currently in use. Wide dotted line markings should 8 inches wide, 3-foot long segments separated by 9-foot gaps, as prescribed in the MUTCD Section 3A.06, paragraph 6. This change could be made when the roadway is next resurfaced to avoid the need for the existing markings to be eradicated, which could scar the pavement. The lane configuration on southbound Glassford Hill Road approaching SR 69 is unconventional because only one lane carries through the intersection, which may be counter to motorists expectations. In this area, both the left and right lanes are drop lanes, so it is recommended that drop-lane markings are used for both lane lines south of Pav Way. It is also recommended that another set of lane-use pavement arrows is installed just downstream of Pav Way, the first point at which the lane use can be unambiguously associated with SR 69. At Granville Parkway (north), a new leg was recently added to the intersection that allows westbound through movements, where previously only rights and lefts were possible. It is recommended that the pavement markings on the westbound approach be modified to include a through-right pavement arrow in the right lane to better communicate the new lane configuration to motorists. Glassford Hill Road Intersection Safety Study Page 51

55 At Granville Parkway (south), aerial photography shows that a stop line was once in place for westbound traffic, but our field visit showed that the stop bar has faded significantly. It is recommended that the stop bar be refreshed. The location of the stop bar could also be adjusted to be closer to Glassford Hill Road, which should help drivers identify a stopping position that might help them achieve a better line of sight to approaching traffic. On the same approach, historic aerial photography from 2011 suggests that lane-use arrow and ONLY pavement markings were once installed but have likely since faded. While the historical use of pavement arrows was probably excessive considering the low volume and familiar nature of traffic, one set of lane use pavement arrows might be helpful to communicate lane use. If the stop bar is relocated as suggested above, it is recommended that yellow pavement markings are installed to provide a left edge line on the westbound left-turn lane and to direct southbound left-turning traffic around the raised median. A suggested pavement marking treatment in this area is presented in Figure 19. Figure 20: Pavement Marking Recommendation at Granville Parkway (south) Image source: Google Maps Glassford Hill Road Intersection Safety Study Page 52