Evaluation of the ADAPTIR System for Work Zone Traffic Control

The ADAPTIR system (Automated Data Acquisition and Processing of Traffic Information in Real Time) uses variable message signs (VMS) equipped with radar units, along with a software program to interpret the data, to display appropriate warning and advisory messages to motorists approaching a work zone when certain speed and delay thresholds are met. The overall conclusion of the evaluation is that the ADAPTIR type system is an effective method to provide real time information to motorists approaching a work zone. The information relates to speed reductions, delay, and possible diversions. Drivers who traveled through the work zone when the VMS were in operation understood the messages and thought they were useful. However, there are limitations which much to considered. The accuracy of the messages is a function of the accuracy of the radar data, the number and location of the radar units, and the logic used to analyze the data. Care must be taken to assure that the radar units used have the capability to record very low speeds and that inappropriate speeds are not being recorded. If the lane closure is very long, additional radar units may need to be placed within the land closure to increase the accuracy of the delay estimates. The logic must be analyzed to insure that motorists are being given appropriate messages.