Effects of Legal and Institutional Issues on TIM Performance Measures – Arizona Example

In early 2011, there was a major policy revision in Arizona requiring police officers to move vehicles off the roadway during incidents – not simply to the shoulder, but preferably outside of view from the roadway (e.g., nearby parking lot). The Arizona Department of Public Safety used performance measures before and after this policy change to determine if it had an impact on TIM performance. The table below compares TIM performance in terms of RCT and ICT for crashes that occurred between October-December 2010 (prior to the policy change) and April-June 2011 (after the policy change). Performance is reported by the injury severity resulting from the crash (non-injury, injury, fatal).

In all categories, performance increased (decrease in average RCT and ICT) after implementation of the policy, suggesting that the policy change was effective at reducing clearance of crashes, particularly non-injury crashes that are more easily moved from the roadway. What is interesting to note is the large decrease in RCT and ICT for non-injury crashes as opposed to less of a reduction for injury crashes and an even smaller reduction for fatal crashes. For injury crashes, the decrease in RCT and ICT does show effectiveness of the policy, albeit less than non-injury crashes. These finding suggest that some injury crashes (perhaps those that are more serious) may not be as easily moved from the roadway. While there was a decrease in RCT and ICT for fatal crashes, the decrease was far less dramatic, suggesting that the policy had less of an impact on performance, which is not surprising given the nature and sensitivity of these crashes.

Arizona DPS Metropolitan Phoenix TIM Performance between Oct-Dec 2010 and Apr-Jun 2011

Injury Category Performance Measure Oct-Dec 2010 Performance Apr – June 2011 Performance Percent Change
Non-injury RCT 45 32 -29%
ICT 84 40 -52%
Injury RCT 54 46 -15%
ICT 94 58 -38%
Fatal RCT 212 198 -7%
ICT 214 211 -2%