Knowledge Resources

This conference paper presented a series of traffic simulations and modeling experiments to support the FHWA Metropolitan Model Deployment Initiative (MMDI) in Seattle, Washington. The study evaluated the potential benefits of integrating arterial-based congestion data with freeway-based advanced traveler information systems (ATIS).

The project was designed using the Mitretek Systems Process for Regional Understanding and Evaluation of Integrated ITS Networks (PRUEVIN). Baseline data was derived from sensors and loop detectors deployed on two major freeways near interstate I-5 (ITS Backbone). The ITS backbone was designed to link traffic data to the Washington Department of Transportation (WSDOT) advanced traveler management system (ATMS) in Shoreline.

The INTEGRATION 1.5 traffic simulation model was used to simulate baseline conditions, freeway-only ATIS traffic conditions, and freeway-and-arterial ATIS traffic conditions.

Baseline (No ATIS): The "Baseline" deployment strategy included pre-trip traveler information in the form of television reports, roadway variable message signs, and highway advisory radio. These information resources have been available to travelers in Seattle for many years.

Freeway Only ATIS: This deployment strategy included pre-trip and en-route traveler information in the form of visual displays on major freeways. This type of deployment strategy was designed to enable travelers to gauge travel times more accurately.

Freeway and Arterial ATIS: This deployment strategy included real-time (refreshed every 15 minutes), pre-trip, and en-route traveler information in the form of visual displays on major freeways and arterial routes. This strategy enabled travelers to gauge travel time and have updated intersection delay information.

Each deployment strategy was evaluated during various peak travel times. Thirty (30) different daily scenarios were modeled. These scenarios included weather impacts, incident patterns, and travel demand variations for 350,000 vehicles over 2,200 links.

RESULTS

Freeway and Arterial ATIS Deployment Simulation (data for 1 year)

Measure per Average AM Peak Period, North Corridor Sub-Area	Baseline	Freeway and Arterial ATIS	Change	Percent Change
Vehicle Throughput	209,372	209,575	203	0.1%
Coefficient of Trip Time Variation	0.242	0.242	0.005	2.1%
Vehicle-Km of Travel	3,438,000	3,443,000	5,000	0.2%
Total Number of Stops	1,200,000	1,134,000	(-66,000)	(-5.5)%

The integration of arterial congestion data with freeway-based ATIS clearly improved the performance of ATIS in the study area.

Freeway Only ATIS Deployment Simulation (data for 1 year)

Measure per Average AM Peak Period, North Corridor Sub-Area	Baseline	Freeway and Arterial ATIS	Change	Percent Change
Vehicle Throughput	209,372	209,382	10	0.0% NS
Coefficient of Trip Time Variation	0.242	0.236	(-0.006)	(-2.5)%
Vehicle-Km of Travel	3,438,000	3,436,000	(-2,000)	(-0.1)% NS
Total Number of Stops	1,200,000	1,201,000	1,000	0.1% NS

The Freeway Only ATIS simulation model generated limited but positive impacts on ATIS performance in the study area.


NS = Not Statistically Significant