This report summarized the results of several ITS evaluation projects in the city of San Antonio, Texas. San Antonio had a relatively extensive implementation of ITS prior to this study and, consequently, the incremental benefits experienced in San Antonio through expansion and additions to the existing system may be somewhat smaller than the benefits that could be achieved in areas with little prior implementation of ITS.
The evaluation report detailed benefits information regarding the implementation of an incident management program with traveler information and dynamic message signs (DMS) along a freeway corridor and traffic signal timing control operations along a parallel arterial. Through a modeling effort, the study investigated the impacts of each implementation individually, and also evaluated the combined impact of integrating the DMS with incident management and then integrating both the DMS and incident management with traffic signal timing plan alterations along an alternative arterial route.
Results indicate that the most effective stand-alone implementation is incident management, recording improvements in all impact measures assessed. DMS and arterial traffic signal control can provide additional improvement under many of these areas. For the particular corridor modeled during this study, optimum implementation of the integrated DMS and incident management results in a 5.7 percent decrease in delay. Integrated use of incident management, DMS and arterial traffic control can achieve an benefit of a 5.9 percent reduction in delay.
The evaluation reports contains several conclusions and recommendations drawn from the results above, and discussions with various stakeholders within the projects:
- A successful ITS deployment requires a strong institutional framework.
- The combined benefit of integrated ITS components may not equal the sum of individual implementations, however this integration can offer improved benefits and costs over isolated deployments. For example, the reduction in delay possible along a particular corridor during a major incident was 16.2 percent with and incident management system operating alone, 4.6 percent with only a freeway management system, 2.8 percent with only an arterial management system, and 19.9 percent with all three systems implemented in coordination. It is also important to integrate the three systems described above in a strategic fashion. Applying all three systems to every incident, regardless of severity, can decrease the overall benefit of the systems by encouraging travelers to unnecessarily change their travel plans during minor incidents.