Other Performance Measures

The three FHWA national performance measures for TIM program assessment are not the sole metrics that can be utilized. They have, however, been put forth with the intent to aid in the comparison of metrics across states and regions, as well as the entire nation. The entire premise of having three national TIM performance measures is to create a sustainable, defined, and comparable basis for TIM program assessment across the boundaries of any given region. Much like on-going efforts on the National Scorecard for Infrastructure, Congestion, and other transportation aspects, the use of three common measures will allow for the analysis of national incident response trends. Consistent and comparable reporting and metrics are an essential tool in promoting TIM and funding for TIM resources.

Although not an exhaustive list, other TIM performance measures that have been used include: (7,13)

  • Number of incidents.
  • Frequency of incidents.
  • Incident delay.
  • Times related to the closure/opening of individual lanes.
  • Severity of incidents.
  • Number of fatalities.
  • Service patrol statistics (e.g. roadway miles covered, number of assistance calls, etc.).
  • After-action statistics (e.g. number of reviews, percent of participating agencies, etc.).
  • Travel delay.
  • Queue length.
  • Incident detection time.
  • Incident verification time.
  • Incident response time.
  • Time to return to normal flow.
  • Detection time.

Interviews with various law enforcement personnel associated with TIM indicate that law enforcement uses a larger set of metrics including:

  • Number of secondary crashes as a result of a primary crash.
  • Number of secondary crashes involving first responders.
  • Percentage of fatal crashes that is secondary.
The critical thing to remember about any performance measure is the need for it to explain a particular goal and objective, be well defined, and utilize performance targets to drive improvements in the program.