1 / 22

Enhanced Safety Prediction Methodology and Analysis Tool for Freeways and Interchanges

NCHRP Project 17-45. Enhanced Safety Prediction Methodology and Analysis Tool for Freeways and Interchanges. James A. Bonneson August 2012. Project Objectives. Objectives Develop safety prediction methodology Freeways Interchanges Develop a software tool that implements the methodology

Download Presentation

Enhanced Safety Prediction Methodology and Analysis Tool for Freeways and Interchanges

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. NCHRP Project 17-45 Enhanced Safety Prediction Methodology and Analysis Tool for Freeways and Interchanges James A. Bonneson August 2012

  2. Project Objectives • Objectives • Develop safety prediction methodology • Freeways • Interchanges • Develop a software tool that implements the methodology • Document in a chapter for a future HSM

  3. Project Oversight • NCHRP • Chuck Niessner, Mark Bush • TRB • Rick Pain • Panel • John Milton, Chair, Washington DOT • James Allen, FHWA, Region 2 • Geni Bahar, NAVIGATS Inc. • Michael Matzke, FHWA, Office of Infrastructure • Johnson Owusu-Amoako, Maryland DOT • Dan Turner, Univ. of Alabama • Clayton Chen, FHWA, Office of Safety R&D

  4. Research Team • Texas Transportation Institute • J. Bonneson , S. Geedipally, D. Lord, M. Pratt • CH2M-Hill • J. Moller, T. Neuman

  5. Project Status • Schedule • Begin: May 2009 • End: August 2012 • Status • Final report and products submitted

  6. Overview • Background • From System to Sites (Segmentation Process) • Freeway Predictive Method • Freeway segments • Freeway speed-change lanes • Ramp Predictive Method • Ramp and C-D road segments • Crossroad ramp terminals • Method Scope

  7. HSM Safety Evaluation Coverage • 2010 HSM Part C Predictive Methods (52%) • Rural Two-Lane Highways (VMT: 362, 088 mvm) • Rural Multilane Highways (VMT: 356,810 mvm) • Urban and Suburban Arterials (VMT: 831,710 mvm) • NCHRP Project 17-45: Freeways (33%) • Freeways (VMT: 963,805 mvm) • Ramps • HSM Coverage (85%) • U.S. Streets and Highways (VMT: 2,966,506 mvm)

  8. Freeway Safety Indicators • Freeway Fatal Crash Rate • Fatality Analysis Reporting System (NHTSA) • U.S. highway system: 1.02 fatal cr/100 mvm

  9. Freeway Segmentation Process • Concept • Disaggregate road system into individual “sites” • Rules for identifying segments and intersections • Application • 3 freeway segments • 5 C-D road segments • 5 ramp segments • 2 speed-change lanes • 1 crossroad ramp terminal In

  10. Freeway Predictive Method • Safety Performance Functions (SPFs) • Lanes: 4, 6, 8, 10 (9, 10 urban areas only) • Guidance for segments with 5, 7, 9 lanes • Crash Modification Factors (CMFs) • Horizontal curve (one roadbed, both roadbeds) • Lane width • Inside shoulder width • Median width

  11. Freeway Predictive Method • CMFs • Median barrier (continuous and pieces) • High volume (portion of vehicles in congestion) • Lane change (weaving) • Outside shoulder width • Shoulder rumble strip • Outside clearance (clear zone width) • Outside barrier (continuous and pieces)

  12. Ramp Segment Predictive Method • Segment SPFs • Lanes: 1, 2 (2 urban areas only) • Ramps, C-D Roads • CMFs • Horizontal curve • Lane width • Right shoulder width • Left shoulder width

  13. Ramp Segment Predictive Method • CMFs • Right side barrier • Left side barrier • Lane add, lane drop • Ramp speed-change lane • Weaving section (C-D road only) • Supplemental Models • Ramp curve speed prediction model

  14. Ramp Terminal Predictive Method • SPFs • 7 configurations • Stop control, signal control Diagonal, Entrance Diagonal, Exit Diagonal, 4-Leg

  15. Ramp Terminal Predictive Method • SPFs • 7 configurations • Stop control, signal control 4-quad Parclo B 4-quad Parclo A 2-quad Parclo B 2-quad Parclo A

  16. Ramp Terminal Predictive Method • CMFs • Exit ramp capacity (ramp lanes and control mode) • Crossroad left-turn lane or bay • Crossroad right-turn lane or bay • Access point frequency (driveway count) • Segment length (distance to next intersection) • Median width

  17. Ramp Terminal Predictive Method • CMFs for Signal-Controlled Terminals • Protected-only left-turn operation • Channelized right turn on crossroad • Channelized right turn on exit ramp • Non-ramp public street leg • CMFs for One-Way Stop-Controlled Terminals • Skew angle

  18. Method Scope • Methods Do Not Address the Following • Ramp meters • HOV by-pass lanes on ramps • Frontage road segments or terminals • Freeways with buffer-separated HOV/HOT lanes • Note: can evaluate general-purpose lanes with barrier separation Barrier (ok) Buffer

  19. Method Scope • Freeway Evaluation Scenarios • Interchange ramp spacing • Weaving section length • Reallocation of cross section width • Interchange Scenarios • System interchange configuration • Service interchange configuration (parclo, diamond) • Analysis Scale • Single year analysis or design life analysis • Freeway system analysis or individual section

  20. Project Deliverables • Draft final report • Main body: documents development of methods • Appendix: Draft HSM Freeways Chapter • Appendix: Draft HSM Ramps Chapter • Appendix: Draft HSM Appendix A for Part C • Appendix: Draft algorithm description

  21. Project Deliverables • Enhanced Interchange Safety Analysis Tool (ISATe) • Excel spreadsheet • User manual • Workshop Training Materials • PowerPoint slides • Course notes • Instructor guide ISATe

  22. Questions – Comments? • Implementation Activity • FHWA is implementing the predictive methods in the Interactive Highway Safety Design Model (IHSDM)

More Related