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This project began in the fall of 2005. At the time CDOT had three different business units maintaining different LRS s. That is, the beginning and ending reference points and the measured length of the routes in the state were in many cases different. Landmark LRM. MM and RefPts can be same or different Regions did not need to report changes to DAU / inventory often acted autonomously from HQ Errors in reference point assignments / notations led to interim problems Include all ROWs 3
In many cases the starting and ending points of the routes were moved from the intersection of the centerline of two routes to the on/off ramp for the route, or a connecting frontage road. Supports crash history and maintenance activities and accounting. 4
DMU team sometimes got info that resulted in an edit, and sometimes not. Represents change in ideology: Highways start on a direct connect ramp. 5
This project pushed us in DTD into aggressively updating the geometric alignments of the roadways in our GIS datasets. The MMS GPS d roads layer, CAD realignments, and the aerial imagery have greatly enhanced the geometric accuracy of our data. This has been a major early benefit of this project. 6
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We agreed to resolve the discrepancies between these LRS s and then move forward with one LRS that met everyone s business requirements. 9
The approach that we took was to compare, route by route, the beginning and end reference points and length in the three different databases, plus historical highway logs, and evaluate their correctness against the most current information that we had. The types of information we used included aerial imagery, GPS d roads from CDOT s maintenance section noxious weeds project, digital video logs from pavement management, as built drawings from the regions, reference to commercial mapping. It was often necessary to evaluate more than the very beginning and end of a route. 10
Colorado uses a (static landmark) milepost reference (LRM) location reference method. Roadway history is moved to the background with directional symbology. Measures originated from DMI recorded segment lengths. These well known places in most situations keep the original or legacy reference IDs. Running lengths, mile grouped lengths and segments lengths are stored as attributes. Cartographic views are used on length events to display accumulated miles. Since legacy references have the same real world location from year to year reference ID s don t change however, segment lengths can change. We have identified a number of areas where it is clear that mileposts have moved from their original (or historic) locations. We can identify where this has probably occurred. When this occurs it presents a disconnect with current and historic databases identifying the locations of traffic accidents as well as highway access locations. Proximity selections and spatial analysis tools detect landmark location errors, sequence and flow inconsistencies. All cause calibration problems. (as shown visible in Yellow) 11
Reference layers and historical stacks must be symbolized to read thru working layers. Directionality is also useful. ORIGINALLY We had 8,280 very short arcs segments connected from begin to end. This was topologically a nightmare lots of managing and overhead problems including odd split point locations and tons of inconsistencies in x,y, and we had little control over the m value locations. After the GPS restructure we now have 471 Total super long Arc segments with sub meter GPS accuracy. (as show here) Our roadway Arc are often exported to CAD for concept design. With the improve roadway base layer precision comes sharper geoprocessing results across the board. 12
Calibration points can also hold location information on: linear roadway type changes, special events, junctions, intersections, RRX, overpass/underpass structures, bridges, signs, speed breaks, accident data as well as regional boundaries. Results: ~34K anchors. Errors locations possible calibration problems. Talk about milepost 10 and then 11 (space) (GPS in new control points) (the Support for Milepost topic) Here, in green are GPS d Milepost signage used as Anchorpoints in black the result of the m value transfer. Interpolation fills in all the location values in between. The Density can change (important inventory locations across the state) Sequence use Increase ArcObjects code, route tools and topology rules were used to find repeating or missordered locations. (space) Expression labels read out clues to real world features. FUN and ADDICTION (space) The most important new component added to our SDE Geo Spatial library. (the component that made the GPS conversion possible) was the use of strategically located point landmarks. Show REGION ERRORS 13
The base layer for most editing operations. PROPOSED VS EXISTING (space) PIXEL CELL SIZE GROUND MEASUREMENTS IF FACILITY FEATURES PIXEL MAPED TO CAD (2) EQUAL POINTS 14
Elevation: Adds a second sectional dimension. 15
At this point over 30,000 Anchor points were produced all holding dynamic landmark, address, m value, location as well as facility management information. At first the m values that were getting transferred producing undesirable results. How are they created. Linear Referencing Tools real world GPS s points At locations: events based on legacy (to from) features By hand Anchor point set vs calibration point set ( type field ) Milepost vs Reference point ( now the same thing ) Snapping existing mapping features, centerline sections, nodes, vertices and coded values to the GPSed collection would require updates to over 12,000 end nodes and over a 2 million vertices. Maintaining connectedness of the thousands of tiny segments was hard to manage and lots of data entry was required to re synchronize begin and end field values. CDOT made the decision to start fresh and LRS enable the entire state using the latest GPS d data set. The change made use of ESRI s advanced editing tools and lots of flips, merges and topology checks. (space) CONNECTEDNES 16
Now that the roadway centerlines reflect the current state highway system (limits and shape), measures can be loaded into a statewide traversal. We have established location control points within the new Anchorpoint FeatureClass. The construction of a new state route with the spatial join of accurate location measures is accomplished with this calibration model. The location of stacked layers play together to set up a datum based on measures and coordinates (much like a linear featureid, address or street number). We think of reference points as (almost run length totals because they originated from DMI field work) but they are truly at locations values spread all across the state. Since many aspects of CDOT s business operation rely on access permits, legal contract, deeds and historic documents our user base is very reluctant to change known landmarks. That is not always possible but with the new frame work strict change control processes are now possible. (Slide Data is Described) 17
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Policy Directive 1606.0 One LRS for CDOT DTD manages the LRS Gives DTD authority to establish processes to maintain LRS for CDOT Procedural Directive 1606.1 Highway realignments Jurisdictional changes Location and placement of mile markers Errors in the LRS Change Management When mileposts have moved from their original (or historic) locations, it presents a disconnect with current and historic databases identifying the locations of traffic accidents as well as highway access locations. This is one reason why are establishing change management procedures. We are building a tool to enable CDOT staff to report details about changes to the LRS. 19
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