Guide for Quantitative Approaches to Systemic Safety Analysis (2020)

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B-1 Document Highlighting Benefits of Systemic Safety Analysis to Decision Makers A P P E N D I X B This two-page document is intended to highlight the benefits of systemic safety analysis to decision makers. Safety engineers and program managers will be able to use this resource to promote systemic safety management approaches to decision makers when requesting funding to support development and/or procurement of systemic safety analysis tools and resources and when explaining the rationale for funding safety improvements selected through systemic safety analysis.

Implementing systemic safety management provides highway agencies with proactive, data-driven approaches for programming safety improvements at locations with the greatest potential for reducing crashes. Rather than chasing crashes around the network from year to year or investing in high-cost treatments at persistently high-crash locations, a systemic approach assesses the likelihood of future crashes at individual sites and programs lower-cost countermeasures across many locations with the potential for future crashes (regardless of recent crash history). Implementing a systemic safety management approach is ideal for addressing common crash types that occur throughout the network, but are not necessarily prevalent at high-crash locations. Focus crash types frequently cited in State Highway Safety Plans that can be addressed using systemic safety management include: • Lane departure • Speed-related • Pedestrians • Rollover • Younger driver • Bicyclists • Fixed object • Impaired driving • Nighttime • Head on • Angle The systemic safety management approach can be used to complement a more traditional crash-history-based approach to prioritizing projects. Combining the two approaches can help ensure that resources are allocated to safety concerns across the system, especially on lower-volume or rural routes that may not generally show up on lists of high-crash locations. Key Features of a Systemic Safety Management Approach • Requires site characteristic data rather than location-specific crash data. • Considers the likelihood of future crashes rather than crash history when prioritizing safety projects. • Programs proven, low-cost countermeasures at a large number of sites with high crash potential rather than high-cost countermeasures at a few high-crash locations. • Can be used to identify all sites on a roadway network that would benefit from implementation of specific countermeasures. STOP CHASING CRASHES WITH SYSTEMIC SAFETY MANAGEMENT Examples of countermeasures applied in a systemic safety management approach include: Roadway segments: • Rumble strips (both shoulder and centerline) • Cable median barrier • SafetyEdgeSM • High friction surface treatments • Enhanced pavement markings • Curve warning signs • Chevrons/delineators • Lane/shoulder widening • Speed feedback signs • Tree/clear zone removal Intersections: • Signal backplates • Crosswalk enhancements – striping, signing, rectangular rapid flashing beacons • Countdown pedestrian signals • Pedestrian refuge islands • Curb extensions • Reflective strips on sign posts • Mini-roundabouts • Lighting Key benefits of systemic safety management include: • Adaptable to agency’s available data and resources and can be implemented in the absence of reliable location-specific crash data. • Sites can be prioritized for improvement even without a recent history of crashes. • Addresses crash types that are spread across the network rather than grouped at a few sites. • Ability to program projects further into the future based on the presence/absence of crash contributing factors that do not change frequently from year to year, like crash history. • Software tools like Safety Analyst and ViDA are available to support a systemic safety management approach. • Complements a traditional “hot spot” approach to programming safety projects. TRANSPORTATION RESEARCH BOARD National Cooperative Highway Research Program Project 17-77: Guide for Quantitative Approaches to Systemic Safety Analysis

STOP CHASING CRASHES WITH SYSTEMIC SAFETY MANAGEMENT ILLINOIS DEPARTMENT OF TRANSPORTATION (IDOT) - In recent years, IDOT broadly deployed shoulder and centerline rumble strips on rural two-lane roads throughout the state using a systemic approach. Using the Empirical Bayes (EB) before-after study approach, IDOT computed crash modification factors (CMFs) for adding paved shoulders with rumble strips and pavement markings and found roadway departure crashes of all severity levels were reduced by 49 percent on rural two-lane roads. KENTUCKY TRANSPORTATION CABINET - In 2011, KYTC began exploring systemic safety management approaches as a complement to their crash-history-based safety management approach. Their systemic program now primarily targets reducing roadway departure crashes. Countermeasures that have been implemented as part of their systemic program include: cable median barriers, rumble strips, high-friction surface treatments (HFSTs), pavement markings, SafetyEdgeSM, tree removal, and signing. KYTC has found substantial crash reductions and benefit-cost ratios greater than 3:1 resulting from systemic strategies including rumble strips, cable median barriers, and HFSTs. MAINE DEPARTMENT OF TRANSPORTATION (MaineDOT) - MaineDOT has been splitting its safety funding approximately 50/50 on projects identified using crash-history-based and systemic safety management approaches. Systemic projects tend to range from $1 to $2 million per year. Starting in 2006, over 500 miles of centerline rumble strips were systemically installed. A simple before-after evaluation of their centerline rumble strip treatment showed a 90 percent decrease in fatal crashes and 16 percent decrease in incapacitating injury lane departure crashes. MINNESOTA DEPARTMENT OF TRANSPORTATION (MnDOT) - MnDOT conducted a systemic analysis of their county roadways in 2013, which generated several technical refinements in safety project development. Using a systemic safety management approach, MnDOT identified more than $250 million of suggested low‐cost safety projects, with the average project cost less than $20,000. Since counties began widespread implementation of systemic projects to address di–erent facility types and crash types, the fatality rate along the county system has dropped by approximately 25 percent. THURSTON COUNTY PUBLIC WORKS DEPARTMENT - Thurston County Public Works Department in Washington State identified roadway departure as a priority crash type to address using roadway safety funding. Since implementing a systemic safety management approach, Thurston County has spent approximately $6 million on systemic projects, addressing all 360 miles of county roads in their jurisdiction, including many locations with no or little crash history. Projects have included installation of signing on curves, enhanced roadway markings, high-friction surface treatments, and rumble strips. Based on a simple before-after evaluation of systemic improvements deployed at curves, Thurston County found a 35 percent reduction in fatal and severe crashes on horizontal curves, representing a quantitative improvement in safety performance at the target locations. Quantitative impacts of systemic safety management programs are most commonly analyzed using a trend analysis, the simple before-after study approach, the shift of proportions method, or the Empirical Bayes before-after study method. Although the analysis methods may not always be the most scientifically rigorous, agencies are finding and reporting benefits from implementing systemic safety management approaches. Several examples are provided below.

Abbreviations and acronyms used without definitions in TRB publications: A4A Airlines for America AAAE American Association of Airport Executives AASHO American Association of State Highway Officials AASHTO American Association of State Highway and Transportation Officials ACI–NA Airports Council International–North America ACRP Airport Cooperative Research Program ADA Americans with Disabilities Act APTA American Public Transportation Association ASCE American Society of Civil Engineers ASME American Society of Mechanical Engineers ASTM American Society for Testing and Materials ATA American Trucking Associations CTAA Community Transportation Association of America CTBSSP Commercial Truck and Bus Safety Synthesis Program DHS Department of Homeland Security DOE Department of Energy EPA Environmental Protection Agency FAA Federal Aviation Administration FAST Fixing America’s Surface Transportation Act (2015) FHWA Federal Highway Administration FMCSA Federal Motor Carrier Safety Administration FRA Federal Railroad Administration FTA Federal Transit Administration HMCRP Hazardous Materials Cooperative Research Program IEEE Institute of Electrical and Electronics Engineers ISTEA Intermodal Surface Transportation Efficiency Act of 1991 ITE Institute of Transportation Engineers MAP-21 Moving Ahead for Progress in the 21st Century Act (2012) NASA National Aeronautics and Space Administration NASAO National Association of State Aviation Officials NCFRP National Cooperative Freight Research Program NCHRP National Cooperative Highway Research Program NHTSA National Highway Traffic Safety Administration NTSB National Transportation Safety Board PHMSA Pipeline and Hazardous Materials Safety Administration RITA Research and Innovative Technology Administration SAE Society of Automotive Engineers SAFETEA-LU Safe, Accountable, Flexible, Efficient Transportation Equity Act: A Legacy for Users (2005) TCRP Transit Cooperative Research Program TDC Transit Development Corporation TEA-21 Transportation Equity Act for the 21st Century (1998) TRB Transportation Research Board TSA Transportation Security Administration U.S. DOT United States Department of Transportation

TRA N SPO RTATIO N RESEA RCH BO A RD 500 Fifth Street, N W W ashington, D C 20001 A D D RESS SERV ICE REQ U ESTED N O N -PR O FIT O R G . U .S. PO STA G E PA ID C O LU M B IA , M D PER M IT N O . 88 G uide for Q uantitative A pproaches to System ic Safety A nalysis N CH RP Research Report 955 TRB ISBN 978-0-309-67355-6 9 7 8 0 3 0 9 6 7 3 5 5 6 9 0 0 0 0