Performance measures are indicators that enable decision-makers and other stakeholders to monitor changes in system condition and performance against established visions, goals, and objectives. Typical safety performance measures relate to the number and rate of fatalities and/or crashes and incidents, emergency response times, public perceptions of safety, etc., for the relevant transportation modes.1
Safety performance measures provide the following benefits to the planning and decision-making process (Source 4):
- Greater accountability to policy-makers, customers, and other stakeholders;
- Greater linkage between the safety goals/objectives identified through long-range planning and policy formulation;
- A better understanding of the impacts of alternative courses of action aimed at improving transportation system safety;
- Improved communication about transportation safety to customers, political leaders, the public, and other stakeholders;
- Increased organizational focus on safety priorities; and
- Information feedback to promote ongoing improvement of business processes as they relate to supporting safety strategies.
Safety performance measures should be relevant to the safety issues and policy/strategy initiatives in a jurisdiction. The number and rate of fatalities, injuries, and/or crashes are commonly used safety performance measures. However, given that safety issues vary across the country, no single set of safety performance measures is applicable to every State and region.
The National Highway Traffic Safety Administration (NHTSA) and the Governors Highway Safety Association (GHSA) have developed a set of safety performance measures that each State will be required to track beginning in Federal fiscal year 2010 (see Table 1). Some of the performance measures listed in the table below (i.e., counts and rates of fatalities, number of serious injuries, number of speeding-related fatalities, and number of pedestrian fatalities) are common to both the infrastructure and behavioral transportation safety area. As State DOTs, MPOs, and other transportation safety stakeholders move forward with developing safety performance measures for the transportation planning process they can take advantage of these data and adopt some of these safety performance measures if appropriate.
Table 1. Safety Performance Measures (Source 5)
| Core Measures | Description | Data Sources |
|---|---|---|
| C-1 | Number of traffic fatalities (three-year or five-year moving averages) | FARS |
| C-2 | Number of serious injuries in traffic crashes | State crash data files |
| C-3 | Fatalities/VMT (including rural, urban, and total fatalities) | FARS, FHWA |
| C-4 | Number of unrestrained passenger vehicle occupant, all seat positions | FARS |
| C-5 | Number of fatalities in crashes involving a driver or motorcycle operator with a blood alcohol concentration of .08 g/dL or higher | FARS |
| C-6 | Number of speeding-related fatalities | FARS |
| C-7 | Number of motorcyclist fatalities | FARS |
| C-8 | Number of unhelmeted motorcyclist fatalities | FARS |
| C-9 | Number of drivers 20 or younger involved in fatal crashes | FARS |
| C-10 | Number of pedestrian fatalities | FARS |
| B-1 | Observed seat belt use for passenger vehicles, front seat outboard occupants | Survey |
| A-1 | Number of seat belt citations issued during grant-funded enforcement activities | Grant activity reporting |
| A-2 | Number of impaired-driving arrests made during grant-funded enforcement activities | Grant activity reporting |
| A-3 | Number of speed citations issued during grant-funded activities | Grant activity reporting |
C = Core measure; B = Behavioral measure; A = Activity measure
The safety performance measures in Table 1 are organized in three categories representing the types of measures often found in practice:
Core measures (also known as outcome measures) relate to the safety goals and objectives established as part of policy or as part of a planning process. These measures allocate resources and measure overall progress. They may include crashes, injuries, and fatalities and can be presented as numbers, rates, percentages, or ratios.
Behavioral measures provide a link between specific safety activities and outcomes by assessing whether the activities influenced behavior. These may include direct observations of safety belt use and vehicle speed or self-reported behavior pertaining to program awareness and attitude obtained through surveys.
Activity measures document safety program implementation and track actions taken by law enforcement, courts, media, education, and others to reduce crashes, injuries, and fatalities.
In addition to the safety performance measures developed by NHTSA and GHSA, some examples of infrastructure-related safety performance measures that can be considered for inclusion in the transportation planning process may include:
- Number of run-off-the-road crashes (core measure);
- Number of fixed object crashes (core measure);
- Number of intersection crashes (core measure);
- Miles of guard cable installed (activity measure);
- Miles of rumble strips installed (activity measure);
- Number of medians installed (activity measure);
- Number of signs updated or warning signs installed (activity measure); and
- Number of intersections with improved signal timing (activity measure).
1 Performance measures are different from evaluation criteria, which relate to assessing the relative safety benefi ts or costs of specifi c projects or for prioritizing alternative safety strategies. The level of detail associated with evaluation criteria is greater than that associated with performance measures.