interactive highway safety design model...
TRANSCRIPT
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Interactive Highway Interactive Highway Safety Design Model Safety Design Model
(IHSDM)(IHSDM)
AASHTO Subcommittee on DesignJuly 21, 2009
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AgendaAgenda
• Overview• Module Discussions• Typical Applications • Relationship to HSM• Status and Future Plan• Additional Resources • Questions / Discussion
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What is IHSDM?What is IHSDM?
• A product of FHWA’s Safety Research and Development Program
• A suite of software tools that support project-level geometric design decisions by providing quantitativeinformation on the expected safety and operational performance
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What Highway Types can What Highway Types can IHSDM Evaluate?IHSDM Evaluate?
• Existing and proposed alternative highway geometric designs
• Facility types:–Two-lane rural highways (2003)–Multilane rural highways (2009)–Urban & suburban arterials (2009)
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What Benefits does IHSDM What Benefits does IHSDM Provide?Provide?
• IHSDM results help project developers make design decisions that improve the expected safety performance of designs
• IHSDM helps project planners, designers, and reviewers justify and defend geometric design decisions
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Measures of SafetyMeasures of Safety
• Nominal safety– Relative to design policy
• Substantive safety– Expected crash frequency
• Operational surrogate measures– Speed reduction entering curves– Average travel speed– Percent time spent following
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Evaluation ModulesEvaluation Modules
• Policy Review• Crash Prediction• Design Consistency• Intersection Review• Traffic Analysis• Driver/Vehicle
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Policy Review ModulePolicy Review ModuleScopeScope
• Checks roadway segment geometry against relevant design policy and “flags”variations
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Crash Prediction ModuleCrash Prediction ModuleScopeScope
• Estimates expected crash frequency based upon roadway geometry and traffic volumes
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Design Consistency ModuleDesign Consistency ModuleScopeScope
• Estimates 85th percentile speed profile along alignment to evaluate operating speed consistency
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Intersection Review Module Intersection Review Module ScopeScope
• Expert system that applies rules of good practice in a comprehensive diagnostic review of a single intersection
• Identifies possible safety concerns and typical treatments
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Traffic Analysis ModuleTraffic Analysis ModuleScopeScope
• Traffic simulation model
• Estimates traffic quality of service measures
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Driver/Vehicle ModuleDriver/Vehicle ModuleScopeScope
• Simulates driving behavior and vehicle dynamics on a two-lane highway
• Provides profiles of predicted speed and other response variables, via a simulation of a single driver/vehicle combination
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Data NeedsData Needs
• Vary by IHSDM evaluation module
• Required vs. “optional” data
• All modules required horizontal and vertical alignment
• Highway Segment Data (all modules) and Intersection Data (CPM, IRM)
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IRM Diagnostic ReviewIRM Diagnostic ReviewEvaluation ReportEvaluation Report
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CPM Evaluation ReportCPM Evaluation ReportExpected Crashes GraphsExpected Crashes Graphs
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Who Uses IHSDM?Who Uses IHSDM?
• Those involved in the highway design process (Designers, Planners, Reviewers)
• State/Local DOTs and their consultants• FHWA Federal Lands Highway Divisions• Transportation Researchers• Universities (Research and Academic Use) • International users
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Typical IHSDM ApplicationsTypical IHSDM Applications
• Evaluate relative safety impacts of alternative designs for EIS
• Evaluate expected safety impacts of recently completed improvements
• Safety analysis of preliminary construction plans
• Evaluate operational impacts of passing/ climbing lanes
• In conjunction with Road Safety Audits
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Typical IHSDM ApplicationsTypical IHSDM Applications
• Quantify relative safety/operational performance of alternatives and compare against other (e.g., environmental, cost) impacts
• Refine alternatives to optimize safety and operational performance
• Evaluate / prioritize 3R safety improvements
• Verify design exception areas
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andand
A.A. Introduction and FundamentalsIntroduction and FundamentalsB.B. Roadway Safety Management Process Roadway Safety Management Process
((SafetyAnalystSafetyAnalyst -- AASHTOWareAASHTOWare))
C. Predictive Methods (IHSDM)Chapter 10 Rural, Two-Lane RoadsChapter 11 Rural, Multilane HighwaysChapter 12 Urban & Suburban Arterials
D.D. Accident Modification Factors (CRF Accident Modification Factors (CRF Clearinghouse)Clearinghouse)
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andand
• FHWA intends IHSDM CPM to be a faithful implementation of HSM Part C methodology
• Current IHSDM CPM (2-lane rural) was basis for HSM prototype chapter
• FHWA implements new models and revises 2-lane rural model once approved for HSM 1st Edition - NCHRP 17-26(02) Project
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Status / Future PlansStatus / Future Plans
• Latest 2008 IHSDM Public Release• 2009 Beta CPM Update: crash prediction
capabilities matching the Highway Safety Manual, 1st edition:– Two-lane rural highways– Multilane rural highways– Urban & suburban arterials
• 2010 IHSDM update along with HSM -AASHTO publication
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IHSDM ResourcesIHSDM Resources
For additional FHWA Safety R&D program information:www.tfhrc.gov/safety/ihsdm/ihsdm.htm
IHSDM Technical Support:[email protected]; (202)-493-3407
IHSDM Wiki and software download (free-of-charge): www.ihsdm.org
IHSDM Training Course: FHWA-NHI-380071 in NHI catalog at http://nhi.fhwa.dot.gov
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Questions / DiscussionQuestions / Discussion
Shyuan-Ren (Clayton) ChenFHWA Safety R&D
Thank you!