During Incident Vehicle Exit to Reduce Time (DIVERT)

Project Description

Two major freeways (I-94 and I-35E) come together in a common section in the vicinity of downtown St. Paul. The Minnesota Department of Transportation Office of Advanced Transportation Systems and the City of St. Paul jointly developed and deployed an incident management project under the acronym DIVERT (During Incidents Vehicles Exit to Reduce Time) to manage the effects of incidents on I-94 and I-35E. The goal of DIVERT is to respond to freeway incidents by routing diverted traffic over City surface arterials in a planned, coordinated manner.

One of the major initiatives of the DIVERT project was to improve the joint management of freeway and city traffic through enhanced institutional cooperation between Mn/DOT and the City of St. Paul. This enhanced cooperation would allow the DIVERT objectives to be achieved through a three phased process of incident detection, route guidance and traffic signal control. In so doing, DIVERT links together two significant systems (Mn/DOT Freeway Management System and City of St. Paul central based traffic signal control system for its downtown network) which formerly had no linkages or interactions.

In the DIVERT concept, incident detection is achieved by having continuous access to freeway detector information from the Mn/DOT Traffic Management Center (TMC). Route guidance is achieved through three means: freeway changeable message signs (CMS) used to inform freeway motorists of incident, static trailblazer route marker assemblies to help guide motorists along the arterial diversion routes, and light-emitting-diode “blank-out” signs to guide motorists back to the freeway over alternate routes. Traffic signal control is achieved through a special download of diversion management timing plans to the field. The DIVERT system runs in the background to the main city central system, and 17 special incident timing plans reside within the DIVERT processor. When the operator initiates a timing plan change, the DIVERT system downloads an override command to the local intersections and then also downloads the selected plan. The selected plan is locally stored and executed at each of the DIVERT arterial intersections during the declared incident management period.