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Safety

A change in traffic accident (also called crash or collision) rates that results from a transportation project has an economic value.

Examples

  • A pedestrian/bicycle bridge is built, eliminating a dangerous intersection crossing for pedestrians and bicyclists.
  • Rumble strips are added to a freeway, reducing the number of drivers who veer off the road.
  • A railroad crossing is moved above grade, eliminating conflicts between trains and pedestrian and vehicle traffic on the street.
  • A sharp curve in a road is eliminated.

Approach

  • Determine how the project would change accident frequency and severity.
  • Choose appropriate unit accident costs to crashes.
  • Estimate the total economic value of the changes in accident rates.

Transportation planning decisions often affect crash risks. Benefit-cost analysis can help identify the most cost-effective projects and evaluate decisions that involve trade-offs between safety and other planning objectives, such as travel speed and vehicle costs.

Safety impact analysis requires information on how a project will affect crash frequency and severity. Most crashes are property damage only (PDO). Casualty crashes, in which somebody is injured, disabled or killed, are less frequent but much more costly to society. Crashes can impose a variety of market and non-market costs, include property damages, traffic delay, emergency response services, medical care and rehabilitation expenses, lost productivity, plus pain, suffering and grief.

Safety evaluation requires monetizing (measuring in dollar values) human life and safety. This can be controversial since some people fear that monetization implies that human life is a commodity, and from some perspectives human life has infinite value (most people would be unwilling to die for any amount of compensation). However, individuals and public agencies often make decisions that require trade-offs between incremental changes in safety and other benefits and costs. For example, motorists may need to decide whether to pay extra for an optional safety feature when purchasing a vehicle, and a transportation agency must decide whether to allow higher traffic speeds, or implement roadway design changes that affect crash rates. Applying monetized values helps make planning decisions that affect safety more consistent, and therefor more efficient and equitable.

Federal and state agencies have developed their own estimates for the economic value of preventing accidents, so the first step in an analysis is to choose which estimates are appropriate. Next, estimate the change in accident rates that the project is expected to create. Finally, use these data to estimate the economic value of the project's safety benefits. 

Sources

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Bureau of Transportation Statistics (Annual Reports), National Transportation Statistics. U.S. Department of Transportation. Available at: www.bts.gov/publications/national_transportation_statistics.

de Blaeij, Raymond J.G.M., Florax, Piet Rietveld, and Erik Verhoef (2003), "The Value of Statistical Life in Road Safety: A Meta-Analysis." Accident Analysis and Prevention 35, pp. 973-986.

Tyler D. Duvall (2008), Treatment of the Economic Value of a Statistical Life in Departmental Analyses, Office of the Secretary of Transportation, U.S. Department of Transportation. Available at: http://ostpxweb.dot.gov/policy/reports/080205.htm.

EDRG (2007), Monetary Valuation of Hard-to-Quantify Transportation Impacts: Valuing Environmental, Health/Safety & Economic Development Impacts, NCHRP 8-36-61, TRB (www.trb.org); at www.statewideplanning.org/_resources/63_NCHRP8-36-61.pdf.

Forkenbrock, D. J., and G. E. Weisbrod (2001), Guidebook for Assessing the Social and Economic Effects of Transportation Projects, Transportation Research Board NCHRP Report 456. Washington, D.C. National Academy Press. Available at: http://gulliver.trb.org/publications/nchrp/nchrp_rpt_456-a.pdf and http://gulliver.trb.org/publications/nchrp/nchrp_rpt_456-b.pdf.

Federal Highway Administration (Annual Reports), Highway Statistics, Federal Highway Administration Office of Highway Policy Information. Available at: www.fhwa.dot.gov/policy/ohim/hs02/index.htm.

GRSP (2003), Estimating Crash Costs, Global Road Safety Partnership (www.grsproadsafety.org). Available at: www.grsproadsafety.org/themes/default/pdfs/Estimating%20crash%20costs.pdf

Paul F. Hanley (2004), Using Crash Costs in Safety Analysis, Public Policy Center, University of Iowa (http://ppc.uiowa.edu/dnn4/PublicPolicybrCenter/tabid/36/Default.aspx). Available at: http://ir.uiowa.edu/ppc_transportation/15.

IRAP (2009), The True Cost Of Road Crashes: Valuing Life And The Cost Of A Serious Injury, International Road Assessment Programme (www.irap.net). Available at: www.irap.net/documents/pdf/iRAPValueoflifeseriousinjurypaper.pdf.

Sonja Kahlmeier, Francesca Racioppi, Nick Cavill, Harry Rutter, and Pekka Oja (2010), “Health in All Policies” in Practice: Guidance and Tools to Quantifying the Health Effects of Cycling and Walking,” Journal of Physical Activity and Health, Vol. 7, Supplement 1, pp. S120-S125.

Henrik Lindhjem, Ståle Navrud and Nils Axel Braathen (2010), Valuing Lives Saved From Environmental, Transport And Health Policies: A Meta-Analysis Of Stated Preference Studies, Environment Directorate, Organisation for Economic Co-operation and Development (www.oecd.org); at www.oecd.org/officialdocuments/displaydocumentpdf?cote=env/epoc/wpnep(2008)10/final&doclanguage=en.

Todd Litman (2003), “Integrating Public Health Objectives in Transportation Decision-Making,” American Journal of Health Promotion, Vol. 18, No. 1 (www.healthpromotionjournal.com), Sept./Oct. 2003, pp. 103-108. Available at: www.vtpi.org/health.pdf.

Todd Litman and Steven Fitzroy (2008), Safe Travels: Evaluating Mobility Management Traffic Safety Benefits, Victoria Transport Policy Institute (www.vtpi.org). Available at: www.vtpi.org/safetrav.pdf.

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TRISP (2005), “Valuation of Accident Reduction,” Economic Evaluation Notes, UK Department for International Development and the World Bank (www.worldbank.org). Available at: http://go.worldbank.org/ME49C4XOH0

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