Identifying Alternative Routes with Integration of ITS into Traffic-Diversion Strategies

Traffic diversion and emergency traffic management strategies call for integration of not only advanced information colleting/disseminating devices such as Changeable Message Sign (CMS), video-detection and loop detection, and control system, but also appropriate roadside signing route guidance systems. Well signage-equipped alternate routes could play a vital role in supporting the congestion alleviation and incident management, especially in a mixed roadway network consisting of freeways, arterials, and local streets. While many researchers claimed the importance of dynamic routes for en route drivers, geographical, geometric and environmental conditions and the category of a specific roadway may objectively define its role as a "permanent" alternate route to certain freeways or major traffic generators/attractors. This raises several issues in identifying such "permanent" alternate routes and integrating a signing route guidance system into the implementation of local intelligent transportation systems. This paper attempts to develop a methodology to identify the "permanent" alternate routes for traffic diversion strategies, and to prioritize Intelligent Transportation Systems (ITS) element candidate locations in the concerned network. A scenario of incident management and operation is demonstrated to discuss how a "permanent" alternate route guidance system could be identified and integrated with ITS, using a mixed network near Los Angeles International Airport as an example. Finally, types of diagrammatic alternate route signs are addressed with design samples.