Seattle Metropolitan Model Deployment Initiative Evaluation: Results and Key Findings from Modeling

At the request of the Joint Program Office for intelligent transportation systems (ITS) of the FHWA, Mitretek Systems conducted a modeling analysis of ITS impacts in support of the metropolitan model deployment initiative evaluation program. The Mitretek modeling study supports the evaluation of the Seattle model deployment Smart Trek, testing a series of hypotheses that could not be addressed in controlled field studies or survey research. Using both a regional planning model and a subarea simulation, the study includes a series of experiments to quantify impacts from integrating ITS technologies and services both across jurisdictions and between functional components. The analysis addressed (a) subarea-wide impacts of traffic signal coordination on major arterials, (b) the impact of integrating arterial data into the current freeway-based advanced traveler information service (ATIS), and (c) interactions at the corridor and the regional levels from concurrent deployment of signal coordination and the enhanced freeway and arterial ATIS. Results from that study have been summarized, detailing findings for a 300-km² mixed freeway and arterial subarea network drawn from the roadway system north of downtown Seattle. The coordination of traffic signals along two major arterials resulted in a 7 percent reduction in overall subarea delay and a 3 percent reduction in total stops. More efficient route diversions for ATIS users result from the integration of arterial data into the current web-based service. At currently estimated levels of ATIS usage (6 percent of travelers), this improved diversion efficiency reduces overall subarea delay (users and nonusers) by over 3 percent.