Local Calibration Factors for Implementing the Highway Safety Manual in Maine

Transcription

1 Local Calibration Factors for Implementing the Highway Safety Manual in Maine 2017 Northeast Transportation Safety Conference Cromwell, Connecticut October 24-25, 2017 MAINE Darryl Belz, P.E. Maine Department of Transportation

2 Approaches to Safety Analysis Old (Reactive) Rank high-crash locations based on observed crash frequency Treat locations that had high observed crash frequencies in the past New (Proactive) Rank sites with potential for safety improvements based on expected crash frequency Treat locations based upon the presence of high-risk roadway features

3 Predictive Analysis Uses crash, roadway, and traffic volume data Provides reliable estimates of an existing or proposed roadway s expected safety performance Helps quantify the safety impacts of transportation decisions, similar to the way agencies quantify: capacity environmental impacts right-of-way construction costs

4 Predictive Analysis Tools Equations Spreadsheets Software Products Crash Modification Factors Clearinghouse

5 What is the Highway Safety Manual (HSM)? AASHTO publication 1 st Edition, dated 2010 Periodically updated, 2014 Supplement 2 nd Edition, targeted for 2020 Presents methods to quantitatively analyze safety at a given site or site type Presents methods to estimate crash frequency and severity

6 What are the benefits of using HSM Predictive Methods? Improve safety outcome Make better use of limited resources/maximize benefit Provide objective evaluation of project alternatives Make better choices for our transportation investments Help with public and political pressure

7 Why does Maine need the HSM? Fatalities Fatality Rate (Per HMVM) Fatalities Fatality Rate 0.00

8 Why does Maine need the HSM? Fatalities by Strategic Highway Safety Plan Emphasis Area 69% Total 41% 62.4 Total 36% 54.2 Total Lane Departure Unbelted Speed 28% 37.4 Total 25% 37.8 Total 13% 19.6 Total Impaired 65+ Year-Olds Motorcycle *Based on Five-Year Annual Averages

9 Why does Maine need the HSM?

10 Why does Maine need the HSM?

11 Why does Maine need the HSM? /safety/

12 Why does Maine need the HSM? Highway Safety Improvement Program (HSIP) to achieve a significant reduction in traffic fatalities and serious injuries on public roads.

13 HSM Components Part A: Introduction, Human factors, and Fundamentals Part B: Roadway Safety Management Process Part C: Predictive Method Rural Two-Lane Roads Rural Multilane Highways Urban and Suburban Arterials Freeways Ramps (2014 supplement) Part D: Crash Modification Factors

14 HSM Predictive Methods Part A Part B Part C Part D Part C Methodology Includes Safety Performance Functions Crash Modification Factors Calibration Applications Example Problems References Worksheets Appendix - Common Procedures

15 Predictive Method Equation N predicted = N spf x (CMF 1 x CMF 2 x ) x C Safety Performance Function (SPF) A regression equation for estimating the predicted crash frequency at a site for base conditions Crash Modification Factor (CMF) For adjusting the base condition in the SPF to specific local site characteristics Geometrics, Roadside Conditions, Lighting, etc. Calibration Factor (C) Adjusts average crash frequencies calculated from the SPF to local site conditions

16 Options to Use Predictive Methods Develop jurisdiction-specific Safety Performance Functions (SPFs) Calibrate HSM base models to local conditions Maine

17 Why Calibrate? HSM models were developed in national studies Roadway segments based on Washington Intersection based on California Maine has a unique combination of characteristics affecting highway safety A heavily forested northern climate Hilly terrain affecting road and intersection alignments A predominantly rural landscape and lifestyle An older population

18 Methodology 1. Acquire a list of sites to be calibrated 2. Randomly sample sites until the appropriate sample size is reached (30-50 sites with at least 100 crashes per year) 3. Collect geometric information needed for SPFs and actual crash data for calibration target years ( , ) 4. Apply HSM-given SPFs to find predicted crashes 5. Calculate calibration factors for each facility type

19 Calibration Factor C = all selected sites observed crashes N predicted(uncalibrated) all selected sites C < 1 overprediction of crash frequencies, multiplying the factor lowers the predictions to match observed frequencies. C > 1 underprediction of crash frequencies, multiplying the factor increases the prediction to match the observed frequencies.

20 HSM Facility Types Rural two-way two-lane highways Undivided segments Three-leg minor stop controlled intersections Four-leg minor stop controlled intersections Four-leg signalized intersections Urban and Suburban Arterials Two-lane undivided segments Three-lane segments with two-way leftturn lanes Four-lane undivided segments Four-lane divided segments Five-lane segments with two-way leftturn lanes Rural multilane highways Undivided segments Divided segments Three-leg minor stop controlled intersections Four-leg minor stop controlled intersections Four-leg signalized intersections Three-leg minor stop controlled intersections Four-leg minor stop controlled intersections Three-leg signalized intersections Four-leg signalized intersections Freeways and Ramps Mainline freeway segments Speed-change lanes Interchange ramp segments Crossroad ramp terminals

21 Facility Types Calibrated Rural two-way two-lane highways Undivided segments Three-leg minor stop controlled intersections Four-leg minor stop controlled intersections Four-leg signalized intersections Urban and Suburban Arterials Two-lane undivided segments Three-lane segments with two-way left-turn lanes Four-lane undivided segments Four-lane divided segments Five-lane segments with two-way leftturn lanes Other Three-leg minor stop controlled intersections Four-leg minor stop controlled intersections Three-leg signalized intersections Four-leg signalized intersections Roundabouts

22 Calibration Data Needs Segment Intersection Rural 2- Lane Urban & Suburban Arterial Rural 2- Lane Urban & Suburban Arterial Required Data Items 8 9 Required Data Items 7 11 Desired Data Items 10 3 Desired Data Items 1 5

23 Example Data Needs for 2-Lane, 2- Way Road Segments Required Data Elements Desired Data Elements Segment Length AADT Curve & Tangent Lengths Curve Radii Lane Width Shoulder Type Shoulder Width TWLTLs Spiral Curve Presence Superelevation Variance Percent Grade Presence of Lighting Driveway Density Passing Lanes Short 4-lane Sections Centerline Rumble Strips Roadside Hazard Rating Automated Speed Enforcement

24 HSM s Default Values Only 4 default values were used Presence of spiral curves Centerline rumble strips Automated enforcement Intersection red light cameras Pedestrian crossing lanes & volume: Estimated based on: Land use Number of through lanes Right/Left turn lanes Median type

25 What are some examples of accessible tools to help collect Maine s data? Google Earth/Maps Video Logs Transportation for Decision Enhancement (TIDE) database Maine Crash Reporting, and Analysis for Safer Highways (C.R.A.S.H.) database As-builts Site Visits

26 Roadway Collection Sample Year 3 AADT Left Side Lane Width Right Side Lane Width Left Side Paved Shoulder Width Right Side Paved Shoulder Width Left Side Gravel Shoulder Width Right Side Gravel Shoulder Width Left Side Turf Shoulder Width Right Side Turf Shoulder Width Curve Radius Curve Length TWLT Lane Presence of Spirals Superelev ation Variance Grade Driveway Density Centerline Rumble Passing Strip Lanes Roadside Hazard Rating Lighting Automated Speed Enforcement

27 Maine Calibration Factors HSM Calibration Factors for Maine Facility Type Sample Locations Maine Calibration Factor 2-Lane Segment Rural 3-Leg Stop Control Intersection Leg Stop Control Intersection Leg Signalized Intersection Lane Segment Lane TWLTL Segment 60* Lane Undivided Segment Lane Divided Segment Urban & Suburban 5-Lane TWLTL Segment 30* Leg Stop Control Intersection Leg Signalized Intersection Leg Stop Control Intersection Leg Signalized Intersection Other Roundabout Intersection 15* 1.66 *100% sample

28 HSM Calibration Completed by MaineDOT Bureau of Planning Rural Two-Lane, Two-Way Roadway Facilities 675 hours $33,000 Urban and Suburban Arterial Facilities 1074 hours $40,000

29 HSM Part Spreadsheets at highwaysafetymanual.org

30 HSM Crash Prediction Tool Worksheet 2A -- General Information and Input Data for Rural Two-Lane Two-Way Roadway Intersections General Information Location Information Analyst Roadway Agency or Company Intersection Date Performed Jurisdiction Analysis Year Input Data Base Conditions Site Conditions Intersection type (3ST, 4ST, 4SG) -- 3ST AADT major (veh/day) AADT MAX = 19,500 (veh/day) -- AADT minor (veh/day) AADT MAX = 4,300 (veh/day) -- Intersection skew angle (degrees) [If 4ST, does skew differ for minor legs?] No 0 Skew for Leg 1 (All): Skew for Leg 2 (4ST only): Number of signalized or uncontrolled approaches with a left-turn lane (0, 1, 2, 3, 4) 0 0 Number of signalized or uncontrolled approaches with a right-turn lane (0, 1, 2, 3, 4) 0 0 Intersection lighting (present/not present) Not Present Present Calibration Factor, C i (1) CMF for Intersection Skew Angle CMF 1i from Equations or Worksheet 2B -- Crash Modification Factors for Rural Two-Lane Two-Way Roadway Intersections (2) (3) (4) (5) CMF for Left-Turn Lanes CMF for Right-Turn Lanes CMF for Lighting Combined CMF CMF 2i CMF 3i CMF 4i CMF COMB from Table from Table from Equation (1)*(2)*(3)*(4) (1) Crash Severity Level Total Fatal and Injury (FI) Property Damage Only (PDO) Worksheet 2C -- Intersection Crashes for Rural Two-Lane Two-Way Roadway Intersections (2) (3) (4) (5) (6) (7) N spf 3ST, 4ST or 4SG Overdispersion Crash Severity N spf 3ST, 4ST or 4SG by Calibration Factor, C i Parameter, k Distribution Severity Distribution Combined CMFs from Equations 10-8, 10-9, or from Section from Table from (5) of (2) TOTAL * (4) Worksheet 2B #NUM! #NUM! #NUM! #NUM! (8) Predicted average crash frequency, N predicted int (5)*(6)*(7) #NUM! #NUM! #NUM!

31 Maine HSM Crash Prediction Tool Variation of NCHRP spreadsheets with added functionality Set up for evaluating several alternatives at one intersection Maine-based calibration factors for overall crash rates are included Maine-based crash type and severity information replaces the default values Allowance for up to three additional crash modification factors has been included A crash cost tab has been added to estimate crash costs (and benefits) of intersection alternatives

32 HSM Project Application

33 Project Overview Town: South Berwick Location: SR SR 91 Facility Type: 4-Leg stop control intersection Features: stop control on SR 91, lighting, left-turn bays on SR degree skew AADT: (major), 5430 (minor) Objective: Low-cost improvement to improve safety

34 Proposed Alternatives Alternative 1 Alternative 2 Alternative 3 Alternative 4 Alternative 5

35 General information and input data Worksheet 2A -- General Information and Input Data for Rural Two-Lane Two-Way Roadway Intersections General Information Location Information Analyst KAZ Roadway SR 236/SR 91 Agency or Company MaineDOT Intersection SR SR 91 Date Performed 11/24/14 Jurisdiction South Berwick, Maine Analysis Year 2014 Input Data Base Conditions Site Conditions Intersection type (3ST, 4ST, 4SG) -- 4ST Unsignalized four-leg (stop contr AADT major (veh/day) AADT MAX = 14,700 (veh/day) -- 14,400 AADT OK AADT minor (veh/day) AADT MAX = 3,500 (veh/day) -- 5,430 AADT out of range Intersection skew angle (degre [If 4ST, does skew differ for minor legs?] No 0 w for Leg 1 (All): 63 Skew for Leg 2 (4ST only): 63 Intersection Skew: Number of signalized or uncontrolled approaches with a left-turn lane (0, 1, 2, 3, 4) 0 1 Number of signalized or uncontrolled approaches with a right-turn lane (0, 1, 2, 3, 4) 0 2 Intersection lighting (present/not present) Not Present Not Present Calibration Factor, C i Maine Calibration Factors for Intersections on Rural Two-Lane Two-Way Roadway Intersections: 4ST=0.38 3ST=0.54 4SG=0.55 (1) CMF for Intersection Skew Angle CMF 1i from Equations or Worksheet 2B -- Crash Modification Factors for Rural Two-Lane Two-Way Roadway Intersections (2) (3) (4) (5) CMF for Left-Turn Lanes CMF for Right-Turn Lanes CMF for Lighting Combined CMF CMF 2i CMF 3i CMF 4i CMF COMB from Table from Table from Equation (1)*(2)*(3)*(4)*(6) Other Crash Modifications CMF Description (6) 1.00 Combined Other Worksheet 2C -- Intersection Crashes for Rural Two-Lane Two-Way Roadway Intersections (1) (2) (3) (4) (5) (6) (7) (8) Crash Severity Level Overdispersion Crash Severity N spf 3ST, 4ST or 4SG by Calibration Factor, C i Predicted average crash N Combined spf 3ST, 4ST or 4SG Parameter, k Distribution Severity Distribution CMFs frequency, N predicted int from Equations 10-8, 10-9, or from Section from Table from (5) of (2) TOTAL * (4) Worksheet 2B (5)*(6)*(7) Total Fatal and Injury (FI) Property Damage Only (PDO)

36 Maine Distribution Tables Tables Affiliated with Crash Statistics: Collision type Locally-Derived Values? Table 10-5: Default Distribution for Crash Severity Level at Rural Two-Lane Two-Way Intersections plus Maine Derived Values Percentage of total crashes HSM-Provided Values Locally-Derived Maine Values Average Cost of Crash by Intersection Type (Locally derived Maine values) Yes 3ST 4ST 4SG 3ST 4ST 4SG 3ST 4ST 4SG 2007 Comprehensive Costs (HSM p 4-87) Crash Cost by Collision Type Fatal Incapacitating injury Nonincapacitating injury Possible injury Total fatal plus injury Property damage only TOTAL Note: HSM-Provided values based on HSIS data for California ( ) $ 14,432 $ 38,486 $ 14,432 $ 4,810,700 Fatal $ 9,850 $ 11,405 $ 4,147 $ 259,200 Incapacitating injury $ 11,945 $ 10,618 $ 10,144 $ 94,800 Nonincapacitating injury $ 11,427 $ 10,726 $ 11,535 $ 53,900 Possible injury $ 125,700 $ 196,200 $ 118,400 overall injury Total fatal plus injury $ 8,900 $ 8,900 $ 8,900 $ 8,900 Property damage only $ 53,200 $ 76,900 $ 46,100 overall TOTAL Collision type Locally-Derived Values? Collision with animal Collision with bicycle Collision with pedestrian Overturned Ran off road Other single-vehicle crash Total single-vehicle crashes Angle collision Head-on collision Rear-end collision Sideswipe collision Other multiple-vehicle collision Total multiple-vehicle crashes TOTAL CRASHES Yes Note: HSM-Provided values based on HSIS data for California ( ) Table 10-6: Default Distribution for Collision Type and Manner of Collision at Rural Two-Way Intersections plus Maine Derived Values Percentage of total crashes by collision type ( HSM Default Values) Percentage of total crashes by collision type (Locally-Derived Maine Values) Three-leg stop-controlled intersections Four-leg stop-controlled intersections Four-leg signalized intersections Three-leg stop-controlled intersections Four-leg stop-controlled intersections Four-leg signalized intersections Fatal and Injury Property damage only Total Fatal and injury Property damage only Total Fatal and injury Property damage only Total Property damage only Property damage only SINGLE-VEHICLE CRASHES SINGLE-VEHICLE CRASHES MULTIPLE-VEHICLE CRASHES MULTIPLE-VEHICLE CRASHES Fatal and Injury Total Fatal and injury Property damage only Total Fatal and injury Total Table 10-15: Nighttime Crash Proportions for Unlighted Intersections Intersection Type Proportion of crashes that occur at night, pni Locally-Derived Values? Yes HSM Provided Values Locally-Derived Maine Values 3ST ST SG Note: HSM-Provided values based on HSIS data for California ( ) Maine Calibrated Crash Data

37 Overall Comparison Crash Costs and Benefits of Intersection Alternatives Intersection Intersection Type Total Crashes per Year Crash Crashes per Year for Comparison Unit Crash Costs ($) Crash Costs ($) Benefits ($) Alternative 3ST (3-leg, 1-stop) Observed Estimated Estimate Total FI PDO FI PDO Annual Pres Worth Present 4ST (4-leg, 2-stop) Predicted Expected to (fatal and (property (based on Worth 4SG (4-leg, signal) Compare injury) damage 10 only) years) Baseline/No-Build 4ST Expected Alternative 1 4SG Predicted Alternative 2 4SG Predicted Alternative 3 4ST Expected Alternative 4 4SG Predicted Alternative 5 4ST Expected Predicted Predicted Predicted Predicted Predicted Predicted Worksheet Source 3A 3A 3A 3B 3B Discount Rate 6% dropdown menu inputs manual inputs

38 Implementation Efforts HSM Lead State Initiative NCHRP HSM training Calibration done for rural 2-lane and urban/suburban facilities Analysis tools in use, refinement in progress Program planning in use for mobility and safety projects Intersection network screening Presented at TRB 95 th (Jan. 2016) as poster P Highway Safety Manual Local Calibration for Rural 2- Lane Roads and Intersections

39 Next Steps with the HSM in Maine Calibration of other facility types Design exception analysis Roadway network screening Freeway and ramps training Recalibration of segments Recalibration of intersections

40 HSM Contacts Edward Hanscom, P.E., Public Service Manager II Maine Department of Transportation Bureau of Planning Dennis Emidy, P.E., Civil Engineer II Maine Department of Transportation Bureau of Planning

41 Thank You The HSM is not so bad once you get your feet wet!