Synthesis of Countermeasure Service Life and Crash Severity Costs User Guide

Background

Crash modification factors/functions (CMFs) are a valuable tool that can help identify the most effective countermeasures to improve roadway infrastructure safety. In addition to CMFs, countermeasure service life and crash severity costs are also needed to conduct an economic appraisal or crash based cost benefit analysis of potential countermeasures for implementation. Crash based cost/benefit analyses provide users with a quantitative measure to assist in the decision making process for determining which safety area(s) or countermeasure(s) would be most cost effective for addressing safety concerns and helping to reduce the number and severity of crashes in a particular area.

While the CMF Clearinghouse provides an online database of all available CMFs, there is not similar documentation of countermeasure service life and crash severity cost information. Therefore, FHWA conducted a synthesis to identify information used by the states for countermeasure service life and crash severity costs. The results of the synthesis are included in this user guide.

Literature Review

Many states have documentation of countermeasures service life and crash severity costs they use for economic appraisals including crash based cost/benefit analyses. Some of this documentation is made publicly available on State DOT safety websites or published in Highway Safety Improvement Program (HSIP) Manuals or other documentation. A literature review was conducted to identify the various sources of available information. Appendix A includes the results of the literature review. Some states are listed twice in Appendix A as multiple sources of documentation were found. If a state is not listed, the research team was unable to find any pertinent information.

The relevant information identified through the literature review was synthesized in two databases, one for countermeasure service life and the other for crash severity costs.  A brief description of the database variables is included in Appendix B. In total, information for 19 states was obtained for countermeasure service life. Countermeasure service life information is available for approximately 345 countermeasures across 18 countermeasure categories. Thirty-one states had documentation of costs used for different crash severities.

Synthesis Results

The results of the synthesis are presented in summary tables that were produced from the countermeasure service life and crash cost severity databases. A description of each summary table is provided below.

Countermeasure Service Life by State

For countermeasure service life, a summary table was made for each of the 15 countermeasure categories used by the CMF Clearinghouse with an additional three categories to include countermeasures categorized as “Resurfacing”, “Structures”, or “Other”. If multiple sources for a state were used, they are listed separately. Service lives for countermeasures (names cleaned for uniformity by the research team) populate the cells. Ranges indicate multiple values for a particular countermeasure name either dictated by the state from the available resource or combined by the research team. An example of a range developed from a combination made by the research team can be found in the “Delineation” category. For countermeasure “Install/upgrade pavement markings/delineators” Illinois includes four types of tapes, paints, and markers with service lives varying from one to four years. Thus the value in the summary table for “Install/upgrade pavement markings/delineators” for Illinois is “1-4”. A description of each field in the countermeasure service life summary tables is provided in Table 1 below.

Table 1. Variables for countermeasure service life summary tables

Variable

Definition

Example/Notes

Countermeasure Category

Countermeasure category used by the CMF Clearinghouse

Additional categories added for “Resurfacing”, “Structures”, and “Other”

Countermeasure Name

Name of countermeasure cleaned for uniformity by the research team

“Widen shoulder (paved)”, “Widen paved shoulder (to 5 ft or less)”, “Widen paved shoulders (to > 5 ft)”, and “Widen shoulder width (paved ADT >2K)” were all renamed to “Widen paved shoulder”

State

Abbreviation of state name

 

Year

Year of source record

 

Source

Name of source with link (if applicable)

Some information was obtained from emails and files sent to the research teams so links are unavailable.

Service Life (populated cells)

Value (or range of values) indicated by state in source

For countermeasure “Install/upgrade pavement markings/delineators” Illinois includes four types of tapes, paints, and markers with service lives varying from one to four years. Thus the value in the summary table for “Install/upgrade pavement markings/delineators” for Illinois is “1-4”.

 

Crash Severity Costs by State

For crash severity cost, only one summary table was generated from the database. In most cases, states reported crash severity costs using the “KABCO” scale where K indicates a fatal injury, A indicates an incapacitating injury, B indicates a non-incapacitating injury, C indicates a possible injury, and O indicates property damage only. Some states indicated additional or other crash severities which are covered in the “Other Crash Severity” fields. A description of each field in the crash severity cost summary table is provided in Table 2 below.

Table 2. Variables for crash severity cost summary table

Variable

Definition

Example/Notes

State

Abbreviation of state name

 

Cost of Fatal Crash (K)

Dollar value of crash severity cost

 

Cost of Incapacitating Crash (A)

Dollar value of crash severity cost

 

Cost of Non-Incapacitating Crash (B)

Dollar value of crash severity cost

 

Cost of Possible Crash (C)

Dollar value of crash severity cost

 

Cost of Property Damage Only Crash (O)

Dollar value of crash severity cost

 

Cost of Other Crash Severity (1) & (2)

Dollar value of crash severity cost

 

Other Crash Severity Description (1) & (2)

Description of crash severity

“Non fatal disabling injury”

Information Source

Name of source (if applicable)

Some information was obtained from emails and files sent to the research teams so source names are unavailable.

Information Source Year

Year of source record

 

Link to Source

Link to source (if applicable)

Some information was obtained from emails and files sent to the research teams so source links are unavailable.

 

Noteworthy Practices

During the course of the synthesis, a few states stood out as having exemplary documentation of countermeasure service life information. Two such examples are California (Figure 1) and Texas (Figure 2). Each provide the name of the countermeasure, a brief description, applicable CMF, service life, cost (if applicable), and crash types addressed. The California document also gives examples of where to use the countermeasure and why it works. These resources are good examples and could be of use to other states in the future development of service life and CMF documentation.


Figure 1. Source: Local Roadway Safety – A Manual for California’s Local Road Owners Version 1.1, April 2013

 


Figure 2. Source: Texas DOT HSIP Work Codes Table (Revised 5/1/2013)

 

Summary

It is important for researchers and practitioners to have as much information as possible when selecting which countermeasures to use to improve roadway infrastructure safety and reduce the number and severity of crashes. Crash based cost/benefit analyses are a great tool for states to use to determine which countermeasures would be most cost effective in improving safety for roadway users. Countermeasure service life and crash severity cost information are necessary pieces to conduct these analyses. The results of this synthesis will provide researchers and practitioners with additional information to conduct economic appraisals of potential countermeasures.

 

 

The information contained in the Crash Modification Factors (CMF) Clearinghouse is disseminated under the sponsorship of the U.S. Department of Transportation in the interest of information exchange. The U.S. Government assumes no liability for the use of the information contained in the CMF Clearinghouse. The information contained in the CMF Clearinghouse does not constitute a standard, specification, or regulation, nor is it a substitute for sound engineering judgment.