METHODOLOGY

The evaluation incorporated actual incident data, Average Comprehensive Costs from the National Safety Council, fuel costs from the Missouri Department of Natural Resources for the 2008 period, etc. The study team used CORSIM, a comprehensive microscopic traffic simulation computer model to simulate the effects of lane blockages on two arterial corridors that are adjacent to I-64. CORSIM modeled various incident scenarios by incorporating traffic data from 2007 (pre-construction) and 2008 (post-construction), incident response times obtained from motorist surveys, and the actual number of responses in the year 2008. Simulations of lane closures of varying durations were performed to determine the delay difference in pre-construction and post-construction conditions. Hourly traffic impact cost information was developed for traffic delay, fuel consumption and air quality impacts.

To determine secondary crashes, an impacted incident area was defined to identify incidents that could be attributable to another initial identified incident. A crash reduction estimation of 5% that all crashes are secondary crashes was used based on a previous study done in St. Louis.

FINDINGS

The evaluation of the I-64 Traffic Response (TR) program deployed during the I-64 re-construction project found the following results:

• The (conservative) estimate of the benefit-cost ratio of TR was 8.3:1.
• TR reduced 183 secondary crashes per year by clearing incidents with minimal delay.
• TR estimates that potential savings from avoided secondary crashes was $4,980,468.
• TR reduced congestion costs per year by $1,034,000.
• TR resulted in a savings of $57,977 by reducing the need for other agencies to respond to incidents.
• TR received highly positive feedback from 800 people who had received service patrol assistance and had responded to a mail-in survey. The responders overwhelmingly cited the program as valuable and effective.

The study team concluded that arterial service patrols should be considered as a mobility strategy for construction projects that reduce corridor traffic capacity.