The methodology for this analysis was based on estimates of crash cost avoidance for the primary types of crashes that can be addressed by the RSC systems on combination vehicles. RSC system benefits were based primarily on reducing the occurrence of large-truck rollovers caused by excessive speed in a curve. To obtain a measure of crash cost avoidance, the number of rollovers that the technology is estimated to prevent each year per vehicle miles traveled (VMT) was determined. Next, using information provided by motor carriers, insurance companies, legal experts, and others, the actual crash costs paid by the motor carrier industry was determined for rollovers. As a result, trucking companies can use this cost information as a basis for juxtaposing and evaluating the potential crash avoidance benefits of RSC systems with the purchase and operational costs of these technologies.

FINDINGS

According to the crash data for 2001–2005 provided by the General Estimates System (GES), an average of 2,079 injury and 1,626 PDO rollovers occurred involving combination trucks with a pre-crash movement of negotiating a curve. Additionally, an average of 137 fatal rollover crashes occurred. Rates of effectiveness or crash prevention rates represent the percentage of crashes that RSC systems would have a high probability of preventing. Using information from simulations and motor carrier feedback, a range of efficacy rates was determined, 53% and 37% respectively, and used to estimate the portion of these types of crashes that could be preventable by RSC systems. Table 1 provides the estimated numeric range of crashes preventable by RSC systems which is obtained by multiplying the number of crashes by the rates of effectiveness.

RSC Efficiency Rates	PDO (Property Damage Only) Rollovers	Injury Rollovers	Fatal Rollovers	Total
37%	602	769	51	1,422
53%	862	1,102	73	2,037

Table 1: Estimated Mean Annual Number of Combination Vehicle Rollover Crashes in a Curve Preventable by RSC Systems by Crash Severity, 2001–2005.