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Data-Driven Safety Analysis

Data-Driven Safety Analysis. Integrating Safety Performance into ALL Transportation Investment Decisions. Agenda. Overview of Data-Driven Safety Analysis DDSA in Planning Alternatives Analysis Design Construction, Operations, and Maintenance Assistance Available. Innovation Overview.

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Data-Driven Safety Analysis

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  1. Data-Driven Safety Analysis Integrating Safety Performance into ALL Transportation Investment Decisions

  2. Agenda • Overview of Data-Driven Safety Analysis • DDSA in • Planning • Alternatives Analysis • Design • Construction, Operations, and Maintenance • Assistance Available

  3. Innovation Overview

  4. What is DDSA? • The application of the latest evidence-based tools and approaches to safety analysis • Provides reliable estimates of an existing or proposed roadway’s expected safety performance • Helps agencies quantify the safety impacts of transportation decisions, similar to the way agencies quantify: • traffic growth • environmental impacts • traffic operations • pavement life • construction costs Source: AASHTO, AASHTOWare, Roadway Safety Foundation

  5. The EDC Data-Driven Safety Analysis Initiative… • Goal: Integrate safety performance into ALL transportation investment decisions Source: FHWA

  6. Foundational DDSA Methods: the AASHTO Highway Safety Manual, first edition • 2010 Release: • Rural Two-Lane Roads • Multilane Rural Highways • Urban/Suburban Arterials • 2014 Supplement: • Freeway Segments • Ramps • Ramp Terminals Source: AASHTO

  7. A Document Akin To the HCM… • The Vision for the HSM 1 2 3 Source: Transportation Research Board

  8. The HSM has resulted in the development of: • Spreadsheets • Software Products • Guidance Documents • Crash Modification Factors Clearinghouse

  9. An Illustration of DDSA… All three of these meet design standards… 110 fatal & injury crashes/year 45 fatal and injury crashes/year 65 fatal & injury crashes/year but DDSA tells us they would perform very differently from a safety perspective. No-Build Alt 1 Alt 2 Source: CH2MHILL

  10. Where can DDSA be applied in the Project Development Process? Source: FHWA

  11. Applying DDSA in Project Development Process

  12. DDSA in Planning Source: FHWA

  13. DDSA in the Planning Process • DDSA tools can be applied to help identify which roadways aren’t performing as they should, determine the scope and need of potential projects, and prioritize them. 13

  14. DDSA in the Planning Process • System Level Planning (Network Screening) • Predictive Analysis • Systemic Analysis • Project Level Planning • Establishing Project Scope • Project Prioritization

  15. DDSA in Network Screening Predictive analysis Uses crash, roadway inventory and traffic volume data to provide more reliable estimates of an existing or proposed roadway’s expected safety performance Systemic analysis Uses crash and roadway data in combination to identify roadway characteristics correlated with particular crash types

  16. Predictive Methods in Network Screening • Advanced Methods are More Reliable • Advanced methods account for potential bias due to: • Regression-to-the-mean • Changes in traffic volume • Nonlinear relationship between crash frequency and traffic volume • Differences in crash severity FHWA-SA-16-039

  17. Level of Service of Safety Example: Montana DOT - Network Screening Credit: Montana DOT Tool: Agile Assets Safety Analyst

  18. DDSA in Network Screening Predictive analysis Uses crash, roadway inventory and traffic volume data to provide more reliable estimates of an existing or proposed roadway’s expected safety performance Systemic analysis Uses crash and roadway data in combination to identify roadway characteristics correlated with particular crash types

  19. The Systemic Approach… • Implements a system-wide screening of a roadway network based on the presence of roadway characteristicscorrelated with particular severe crash types, rather than high crash locations. Source: FHWA Systemic Safety Project Selection Tool

  20. A movement away from chasing dots (fatalities)… Anystate, USA 2015 2013 2012 2014 2016

  21. Limitations to the Site Analysis Approach About 57% of fatal crashes are on rural roads A further challenge is that crashes on the local system might not have robust data to assist with identifying locations of concern Crashes on rural roads often account for a high percentage of severe crashes, but the density of crashes on rural roadways is typically low and may not lead to identifying crash concerns within the “traditional” site-based analysis process.

  22. Systemic Approach • Particularly applicable when a significant number of severe crashes happen over a wide area: • Rural Roadways • Local Roadways • May focus on specific crash types • Cross-median • Pedestrian • Curve May include treating locations that haven’t experienced severe crashes Photo Source: FHWA

  23. Example: Local Road Safety Plans (LRSPs) • Provide a framework for local practitioners to take a proactive stance to identify the specific or unique conditions that contribute to crashes within their jurisdictions • Utilize the 4 E’s as appropriate to address safety issues • Provide an excellent opportunity for agencies at all levels of government (local, State, and Federal) to work together to align and leverage resources to address those safety challenges

  24. Systemic Approach to Safety Example: Minnesota DOT - Network Screening Source: FHWA https://www.youtube.com/watch?v=jVds3AWWqbk

  25. DDSA in the Planning Process • System Level Planning • Network Screening • Project Level Planning • Establishing Project Scope • Project Prioritization

  26. Establishing Project Scope • Typical process: • Assess the performance of the existing site • Condition/status of pavement, structures, congestion, safety, etc. • Propose improvements • Determine necessary funding and schedule • Done at a level commensurate with the type and scale of the project

  27. Example: Colorado DOT Safety Analysis in Scoping • The Transportation Safety Management & Operations (TSM&O) Evaluation consists of three parts • Safety, Operations, and ITS analyses • The TSM&O Evaluation makes recommendations for improvements related to Safety, Operations, and ITS • All projects require a TSM&O Evaluation. Safety Operations ITS TSM&O Evaluation Recommendations Improvements Incorporated in Project Credit: Colorado DOT

  28. Safety Analysis in Project Prioritization • Typical process: • Identify criteria for scoring projects • Develop list of potential projects • Apply scoring methods for each criteria • Rank and prioritize list of projects

  29. Example: Virginia DOT – Safety Performance in Project Prioritization Project Weighting Factors Credit: Virginia DOT

  30. DDSA in Alternatives Analysis Source: FHWA

  31. DDSA in Alternatives Analysis • DDSA tools can predict the number and severity of crashes for each project alternative, allowing safety performance to be considered along with other project criteria. 31

  32. Integrating Safety into NEPA Analysis Policy/Stakeholder Involvement Source: FHWA http://safety.fhwa.dot.gov/tsp/fhwasa1136/fhwasa1136.pdf Source: FHWA

  33. When might a more-robust safety analysis in the environmental phase be appropriate? • When Safety is included in the Purpose and Need • Projects that claim a safety benefit • Projects where there could be a substantial difference in safety for the alternatives being considered • Projects with existing safety issues

  34. Purpose and Need example… Level 2 Alternatives Evaluation Matrix ***For illustration purposes only***

  35. Example – Burlington County, New Jersey Intersection Credit: Burlington County

  36. Evaluating Intersection Alternatives Example: Burlington County, NJ Source: FHWA https://www.youtube.com/watch?v=cHv086TQ2LI

  37. Example – Burlington County, NJ Intersection • Alternatives Analysis: signalized Intersection vs. Roundabout • Feb 2012: fatal crash involving school bus occurs • Sept 2012: HSIP funding would require HSM analysis • Oct 2012: DVRPC offers to assist Burlington County with HSM Analysis • Jan 2013: HSIP project application submitted & approved • Jun 2014: Roundabout opened to the public Credit: New Jersey DOT 37

  38. Example: Louisiana DOTD – EIS Alternatives Analysis I-12 to Bush, LA • Four alternatives were considered to replace a two-lane, un-divided roadway with a four-lane, divided roadway with controlled access • All four alignments predicted a reduction in crashes from the No Build alternative Credit: Urban Systems, Inc. and Louisiana DOTD

  39. Example: LA DOTD – EIS Alternatives Analysis • Potential Reduction in Crashes, Costs Credit: Louisiana DOTD

  40. Example: LA DOTD – EIS Alternatives Analysis • Benefits from use of IHSDM • Quantify safety costs and benefits • Safety given equal weight in comparative analysis • Corps of Engineers selected Alternative Q, which had a predicted crash reduction of 6% and a $1.5M cost savings to society

  41. DDSA in Design Source: FHWA

  42. DDSA in the Design Process • DDSA can be used to determine optimal design criteria, considering both safety and cost. • DDSA helps justify flexibility in design • design exceptions • performance-based practical design

  43. Performance-based Practical Design • An approach to decision-making that encourages engineered solutions rather than reliance on maximum values or limits found in design specifications • Characteristics • grounded in performance management • exercises engineering judgment to address purpose and need • uses appropriate performance-analysis tools • considers both short- and long-term project and system goals

  44. Example: AZ DOT Analysis of Design Criteria (MP 441 to 466) Credit: Arizona DOT Alternative Improvements Included: • Widening to 5 ft shoulders • Widening to 8 ft shoulders 44

  45. Example – Arizona DOT Plot of Geometric Features and Expected Crashes Credit: Arizona DOT 45

  46. Example – Arizona DOT Crash Prediction Results • Safety Analysis: • Model was un-calibrated as used (not necessary for comparative alternatives analysis) • Alternative B (8-ft shoulders) would reduce crashes by 4 percent more than Alternative A (5-ft shoulders) Credit: Arizona DOT 46

  47. Example – Arizona DOT • Economic analysis: • Although Alternative B (8-ft shoulders) could provide the greater benefit in reduction in fatal and injury crashes, Alternative A (5-ft shoulders) would provide the greater return on investment and was selected as the preferred alternative. Credit: Arizona DOT 47

  48. Example: MN DOT – PBPDUS Hwy 10 Access Study Source: Bolton & Menk Credit: Anoka County and Minnesota DOT

  49. Example: MN DOT – Communicating PBPDUS Hwy 10 Access Study Source: Bolton & Menk Credit: Anoka County and Minnesota DOT

  50. Construction, Operations, and Maintenance Source: FHWA

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