CREATING CURVE DATA ON LOCAL ROADS TO SUPPORT SAFETY ANALYSIS

Transcription

1 CREATING CURVE DATA ON LOCAL ROADS TO SUPPORT SAFETY ANALYSIS Session April 11, :30pm Michael Trunzo, VTrans, Montpelier, VT Joe Breyer, Works Consulting, Gilbert AZ Vermont Agency of Transportation

2 VTrans has curve data for all of our state highways, but not for any local roads which make up over 80% of Vermont s highways. We need this data to support crash analysis, but it would be too expensive to collect the data in the field through traditional methods. Works Consulting provides a better solution: generate curve data directly from the road centerline geometry.

3 Rural roads are the deadliest roads. Dugway Rd. Richmond, VT March 2016

4 The majority of highway fatalities occur on rural roads. In 2014, 19% of the U.S. population lived in rural areas, but rural fatalities accounted for 51% of fatal crashes.

5 Mud Season In not necessarily the most ideal conditions.

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7 By analyzing curves combined with crash data, we can identify locations in need of safety improvements.

8 So how to generate curve data for the rural local roads in a cost effective manner, and with good accuracy and reliability to feed the analytical tools? Works Consulting is providing the solution for the creation of the curve data through processing of the road centerline geometry. Joe Breyer can provide some insight to the process and how this is done.

9 START WITH POLYLINE M FEATURES Prior to VTrans providing their data, we went to FHWA and had the LRS from previous HPMS submittals on DVD. Alternatively, we could build routes on provided arcs, but that would establish (perhaps different measures). Either way, we screen the UPACS route network or the arcs built upon Route ID values for LRS anomalies using our LRS Data Reviewer. Polyline ZM also usable, though we would drop the Z s to calculate the curve wedges 75,169 arcs 20,053 miles

10 WEDGE GENERATION Wedges are created along a route using Construct Horizontal Curves Calculated by one of 2 analytic methods. All wedge begins and ends are reported by route measure Where road direction reverses (Scurves), curve direction reverses into a new wedge Sharp corners (i.e. two vertices with more than Maximum Chord Length ) are not allowed to participate in a wedge. Raw 3-point curve calculations helpful for discerning variable curvature (i.e. spirals) These curves paint in solid shapes

11 WEDGES GENERATED See Detail to Right

12 WEDGE DISSOLVE Adjacent curve wedges are merged into composite curves using Dissolve Horizontal Curves Adjacent wedges with similar intravertex spacings are merged together and radius/degree is recalculated on the composite Tool assumes that radically different spacings on adjacent vertices suggests variable curvature. Allows for spiral curves to be detectable by preventing adjoining wedges from merging These wedges render hollow in map with outline florescent shapes

13 Raw on white Dissolved on white Raw and Dissolved on white Dissolved on Imagery

14 WIDER AREA EXAMPLE

15 WEDGE SUMMARIZE Polygonal curve wedges are turned into polyline events using Compile Horizontal Curves The PolylineM routes are utilized for rendering even though the LRS details were traveling with the wedges The output feature class is linear and makes for easier labeling And there is tabular output that satisfies your cravings for curvature event data already calibrated to your LRS routes.

16 CURVATURE LINES (WITH WEDGES) See the lines? Now ArcMap can draw better labels TABULAR ATTRIBUTES Cyan highlights show the 4 wedges at right Notice two F curves in a row? An S-curve.

17 TABULAR ATTRIBUTES Extensive Metadata RowUpdated and DateAdded SHAPE_Length = 0? not yet refreshed long radii wedges not drawn See 5 consecutive A curves? not yet dissolved

18 MANUAL SOLUTION User can always check results with simple 3-point geometric solution Also, use the Select, Replace, and Apply buttons to override the automatic calculations of the Raw and Dissolve tools (That s why attribute RowUpdated exists) Change the shape and color of the drawn points with the P and C button

19 TYPICAL ISSUE #1 Poor shape relative to aerial imagery

20 TYPICAL ISSUE #2 Poor visibility of roadway due to tree cover (maybe?)

21 TYPICAL ISSUE #3 Erratic vertex spacing suggesting variability in curvature.

22 TYPICAL ISSUE #3 CONTINUED Erratic distancing between vertices bulges (shown) and gaps =90deg =90deg >90deg

23 FIXING THE DATA (QUALITY CONTROL) Majority of the project focused on improving digitization of Vermont s centerline file Resources: imagery, LIDAR Pan Tracker tool Consultant focus on Vermont s local roads with the most crashes and highest curve indices VTrans staff focus on federal aid roads

24 CURVY ROADS Challenge Larry (the Cable Guy) assertion that the Dragon (in TN) is the curviest road in America? We have a way of measuring that now on a nationwide basis thanks to ARNOLD.

25 CURVINESS INDEX A-Curves have the lowest value (1), and Fcurves have the highest value (6) Weighted-average curvature of a route Useful in prioritizing the roads which will (or might) require the most editing. Challenge Larry (the Cable Guy) assertion that the Dragon (in TN) is the curviest road in America?

26 POTENTIAL ERROR Sampling of Edited Collectors and Arterials Statistical analysis What s the probability that my curve begin and curve end is accurate enough for analysis without further editing? Helps answer the question as to whether an agency should invest in better digitization to improve curve data. Employ Point and Reach tool to gather observations for roads that have been edited to determine the feet of potential error in diagnosing whether a crash within so many feet of a curve is actually on the curve. Plot 1 st, 2 nd, and 3 rd standard deviations 1 2 3

27 PERFORMANCE MEASUREMENT The benefit of editing vertices to improve the validity of curve data can be measured using before and after (i.e. editing) studies on the Curve Class value. The measure of the route is essentially a static and minimally affected by vertex movements.

28 MIRE DATA ELEMENTS 107. Curve Identifiers/Linkages 108. Curve Feature Type 109.Horizontal Curvature Degree (or Radius) 110.Horizontal Curve Deflection Angle 111.Superelevation 112.Spiral Curve Presence 113.Intersection/Deflection Angle 114.Curve Direction

29 OTHER ITEMS OF INTEREST Budget/Schedule continuing through August Consultant is using disconnected editing in Gilbert AZ with nightly check-ins to Montpelier VT. VTrans has legacy curve events culled from construction plans for comparison. Curve & Grade Tools for ArcGIS we didn t talk about gradient! Our booth

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31 Questions? Michael Trunzo Vermont Agency of Transportation