1. 1 SPR 667 – Assessment of Statewide Intersection Safety Performance TAC Meeting August 31, 2009 2:00-3:30PM

2. Agenda 2 ItemLength Introductions and agenda [Joerger]5 Meeting objectives [Joerger]5 Review of Tasks [Research Team]15 Summary of Progress [Research Team] Revised Work Plan [if needed] [all] 50 15

3. Meeting Objectives

4. Research Objectives To quantify the safety performance of typical intersections –To assemble a statewide inventory of intersections including location, geometry, control and volume data. –To characterize by a variety of geometric, operational, and volume features the safety performance of typical intersections. This performance will include both statistical summaries and exploration of the applicability of predictive models. 4

5. Review of Tasks 1.Project Initiation – complete 2.Literature Review – complete 3.Data Assembly & Research Design – 90% complete 4.Pilot Study – 85% complete 5.Full Intersection Study – 20% complete 6.Summary Data Analysis – 20% complete 7.Develop Safety Performance Functions 8.Final Report Budget: $122,516 Encumbered: $42,086 (34%) Balance: $80,430 5

6. Background Nearly 21% U.S. fatalities were identified as intersection or intersection-related (2007) ITE estimates 50% of all reported crashes occurred at intersections –55% of injury crashes –48% of property-damage crashes. Oregon (2007) intersection crashes accounted for 38% of total –18% of fatal crashes –39% of injury crashes 6

7. Literature Review PART 1 –A summary of individual geometric, operation, traffic control, and other features PART 2 –Statistical summaries –Methods for pattern diagnostics –Modeling the safety performance at intersections. 7

8. PART 1 Sources for Intersection Elements Harwood et al. “Safety Effectiveness of Intersection Left- and Right- Turn Lanes” Model Minimum Inventory of Roadway Elements (MMIRE) Highway Safety Manual (HSM) Draft 3.1 Elvik and Vaa “Handbook of Road Safety Measures” Other research List is not exhaustive 8

9. Geometric ElementsTraffic Control and Operational Features Type of IntersectionType of Traffic Control Roundabouts  Uncontrolled  Number of Circulating Lanes in Roundabout  Yield-Controlled  Island Diameter of Roundabout  STOP-Controlled  Sight Obstructions in Roundabout  Traffic Signal Controlled  Number of Approach Lanes Signal Timing  Approach Width  All Red Clearance Interval Number of Approach Lanes  Yellow Clearance Interval  Approach Lane Width  Type of Left-Turn Phasing Vertical Alignment  Right-Turn Arrow Overlap Horizontal Alignment  Lead or Lag Left-Turn Left-Turn LanesTurn Prohibitions  Type of Left-Turn Treatment  Right-Turn on Red  Length of Left-Turn Lanes  Left-Turn Prohibitions  Taper Rate  U-Turn Prohibitions  Offset Left-Turn Lanes Advance Warning Signs Right-Turn LanesLighting  Type of Right-Turn Treatment Red-Light Camera Enforcement  Length of Right-Turn Lanes Pavement Friction Curb Return RadiusPavement Marking Conditions Intersection SkewPresence of Trans. Rumble Strips Intersection Sight DistanceTraffic Characteristics Median TypeAverage Annual Daily Traffic  Median Width Peak Hour Approach Volumes Fixed ObjectsTurning Movement Volumes Presence of At-Grade Rail CrossingTraffic Comp. (Percent Trucks) Presence of DrivewaysAverage Approach Speed Presence of On-Street ParkingBicycle Volumes Presence of SidewalksPedestrian Volumes Pedestrian Crossing FeaturesOther  Max No. of Lanes crossed by Pedestrians Weather  Dist from Approach Stop Bar to Ped Cross Land-Use Characteristics  Width of Pedestrian Refuge  Urban and Rural  Curb Extension Presence of a Bicycle Lane 9

10. PART 2 Statistical Summaries (Crash Rates) StudyStateNumber of Intersections Number of Crashes Number of Years Knapp and Campbell, 2005 Wisconsin1,70033,0003 Green and Agent, 2003 Kentucky7,09718,7783 Hanna et al, 1976 Virginia3002,3002 Bonn, 1994Oregon413?3 Iowa DOT, 1989Iowa3,416?5 Cotrell and Mu, 2005 Utah??10, 3 Pant and Nagaraju, 2007 Ohio1,104?3 10

11. Geometric ElementsTraffic Control and Operational Features Type of IntersectionType of Traffic Control Roundabouts  Uncontrolled  Number of Circulating Lanes in Roundabout  Yield-Controlled  Island Diameter of Roundabout  STOP-Controlled  Sight Obstructions in Roundabout  Traffic Signal Controlled  Number of Approach Lanes Signal Timing  Approach Width  All Red Clearance Interval Number of Approach Lanes  Yellow Clearance Interval  Approach Lane Width  Type of Left-Turn Phasing Vertical Alignment  Right-Turn Arrow Overlap Horizontal Alignment  Lead or Lag Left-Turn Left-Turn LanesTurn Prohibitions  Type of Left-Turn Treatment  Right-Turn on Red  Length of Left-Turn Lanes  Left-Turn Prohibitions  Taper Rate  U-Turn Prohibitions  Offset Left-Turn Lanes Advance Warning Signs Right-Turn LanesLighting  Type of Right-Turn Treatment Red-Light Camera Enforcement  Length of Right-Turn Lanes Pavement Friction Curb Return RadiusPavement Marking Conditions Intersection SkewPresence of Trans. Rumble Strips Intersection Sight DistanceTraffic Characteristics Median TypeAverage Annual Daily Traffic  Median Width Peak Hour Approach Volumes Fixed ObjectsTurning Movement Volumes Presence of At-Grade Rail CrossingTraffic Comp. (Percent Trucks) Presence of DrivewaysAverage Approach Speed Presence of On-Street ParkingBicycle Volumes Presence of SidewalksPedestrian Volumes Pedestrian Crossing FeaturesOther  Max No. of Lanes crossed by Pedestrians Weather  Dist from Approach Stop Bar to Ped Cross Land-Use Characteristics  Width of Pedestrian Refuge  Urban and Rural  Curb Extension Presence of a Bicycle Lane 11 District or region Functional class

12. PART 2 Statistical Summaries 12

13. PART 2 Pattern Diagnostics and Proportions Excess proportions –HSM/Safety Analyst Direct diagnostics –Comparisons of individual crash type proportions to all others 13

14. PART 2 Safety Prediction Methods Regression models –Negative Binomial models –Tree-based regression –Probit models Urban – rural Intersection type Severity or crash type Volumes significant in all models 14

15. Literature Review Conclusions Identified a long list of potential intersection elements Crash rates varied considerably from state-to-state Most summaries aggregated at relatively high level Interestingly, all summaries used total crashes and did not develop separate injury rates or rates by any other crash category or causation. –Roundabouts were not included as separate category –Pedestrian or bicycle elements were also absent. All of the summaries are “snapshots” in time and do not appear to routinely updated. 15

16. Literature Review Conclusions Summarizing the crash data in terms of typical diagnostics appears to be very valuable effort. Data requirements for predictive models are significant and a primary reason why there has been limited development. The relationship of intersection characteristics with crash frequency, crash severity, and particular crash types is complex. In nearly every model, volumes were a significant variable. 16

17. Data Assembly ODOT CAR Code Setup Book –State highway system intersections (9,139) –Other system (143,186) ODOT Crash Data System (via OrTSDA) ODOT Digital Video Log (DVL) ODOT Integrated Transportation Information System (ITIS) Google Earth / GIS Files Counts –Traffic counting firms –City/County Engineering & Planning Offices –PORTAL, Google Traffic 17

18. Intersection Crash Data State Highway –Highway and milepost City –Intersecting street numbers County –Either mileposted or intersecting street numbers 18 IntersectionPossible Intersection-related

19. ODOT CAR Code Setup Book 19

20. CAR Setup Book Traffic Control Highway System Intersections Non- Highway System All System Percent of Total Uncontrolled632 380.2% Signal-controlled1,7594,281 6,04032.6% Flashing beacon, red 734 410.2% Flashing beacon, amber 2024 440.2% Stop-controlled1,7159,624 11,33961.2% Yield-controlled324 270.1% One way street730261 9915.3% Total4,24014,290 18,530 20 Remaining records “NULL” traffic control

21. Pilot Study Objectives –Test data collection strategies –Define feasible data elements –Estimate effort –Help formulate likely data distributions –Test crash data scripts and summaries All data elements –49 NCHRP Flashing Yellow Arrow Intersections –55 HSM Calibration Project Intersections Partial data elements –244 State highway–state highway intersections 21

22. Google Earth Map of Intersections 22

23. 23

24. 24 Land UseTypeMajorMinorCount Rural4-LeggedSignalized15 4-way STOP 2 Minor STOP33 Flashing AmberFlashing Red7 3 3-LeggedSignalized 2 Minor STOP82 4-way STOP 2 Flashing Red 1 Flashing AmberFlashing Red3 Flashing AmberSTOP1 Uncontrolled 3 154 Urban4-LeggedSignalized 136 Minor STOP9 Flashing AmberFlashing Red1 1 Roundabout 1 3-LeggedSignalized35 4-way STOP 1 Minor STOP8 Minor YIELD 1 193

25. Data Collection Form 25

26. Data Collection: Google Earth Google Earth can provide an aerial view of: -Intersection Type -Turning Lanes -Parking -Channelization -Lat/Long Coord. -Urban/Rural -Bicycle Facilities -Ped. Facilities -Measurements -Length, Width

27. Data Collection Resolution is an issue in rural areas when making measurements. John Day: US 26 (005) and US 395 (048)

28. Digital Video Log ODOT’s Digital Video Log provides street level views which can be used to identify: –Signalization-Intersections (ex: S = 3 = S) –# of Turning Legs-Medians and Channelization

29. AADTs from Jurisdictions 29

30. Counts from Traffic Firms 30

31. Variable Summary (N=104) 31

32. Variable Summary (N=104) 32

33. Crash Frequency (N=347) 33 Intersection Characteristic Number of Intersections in Sample Percentage of Total Intersections Number of Crashes 2 year total Percentage of Total Crashes Area Type Urban19356%157289% Rural15444%18811% Traffic Control Signalized18755%155489% 4-Way Stop103%201% Minor Stop14342%16910% Minor Yield21%136% Uncontrolled43%42% Average Annual Entering Volumes (AADT) – Vehicles (2007 Counts) < 10,00011545%898% 10,000 <= x <= 20,000 6827%21220% > 20,0007128%78072% DRAFT-DRAFT – DRAFT – DRAFT- DRAFT - DRAFT

34. Crash Rates (N=254) 34 Intersection Characteristic Crash Rate (per million entering vehicles) Max Crash Rate in SampleStd Dev Area Type Urban0.4242.350.447 Rural0.3034.130.640 Traffic Control Signalized0.4272.350.456 4-Way Stop0.2150.210.295 Minor-Stop0.3270.330.664 Minor YieldSmall Sample Size-- UncontrolledSmall Sample Size-- Average Annual Entering Volumes (AADT) - Vehicles < 10,0000.3214.130.710 10,000 <= x <= 20,0000.2821.320.284 > 20,0000.4812.350.493 DRAFT-DRAFT – DRAFT – DRAFT- DRAFT - DRAFT

35. Crash Patterns 35 DRAFT-DRAFT – DRAFT – DRAFT- DRAFT - DRAFT

36. Crash Patterns By Vehicle Movement 36

37. Draft Results from Pilot Study Many elements probably not needed for summaries / patterns Crash script developed –Refining / testing in Access database –Quality control checks needed Traffic volumes –Hardest to get (off state system) –Time challenge (year of data collection) –Still some other avenues to pursue Signal timing Need to study appropriate aggregations 37

38. Work Plan Deliverables 1 - Literature review 2 - Brief memo to TAC summarizing findings, progress, and recommendations for pilot study intersections and scope 3 - Interim report summarizing findings of the pilot study, progress, and recommendations for full field study. Preview of statistical summaries that will be conducted. 4 - Interim report summarizing the results summary data analysis 5 - Final report 38

39. Revised Work Plan Discussion 39