An evaluation of the impacts of changeable message signs on freeway diversion

The focus of this research is to evaluate the Changeable Message Sign (CMS) component of the Intelligent Transportation Systems (ITS) construction project completed within southeastern Michigan. The changeable message sign and detector loop infrastructure construction began in 1997. The construction and field testing phases are scheduled for completion in 1999 by the Michigan Department of Transportation contractor.;This research will explore three field sites within the ITS expansion area. The three sites were selected due to their configuration which allows a driver to make a choice to divert to a route other than their present route of travel. This diversion decision may be impacted by the changeable message sign display that exists along their travel path upstream from the decision point. Volume data for each site was obtained by analyzing the available loop detector measures of volume, speed and occupancy. Each site was analyzed on the basis of 'with' and 'without' CMS message activation. The 'without' condition includes site analyses during periods when either a blank or default message is displayed. The 'with' condition consists of periods when a specific informational type of driver information is displayed. Statistical significance of driver propensity to divert was analyzed based upon a comparison of traffic volume on the alternate routes.;A simulation analysis of each site was completed using the FRESIM component of the CORSIM simulation software to determine simulated driver delay, and compare actual and simulated traffic speeds.