A robust model for optimal time-of-day speed control at highway work zones

This paper proposes a new speed control strategy, named time-of-day speed limit (TOD SL) control, for highway work-zone operations. The main purposes of the TOD SL control are to overcome the difficulty in setting the optimal real-time speed limit due to the lack of detectors and to maximize the use of available data such as the historical volume data on the target work zone. Its core logic is to divide the entire day of operations into a number of control periods and to accommodate the time-varying traffic conditions within each control period. The measure of effectiveness (MOE) selected in the TOD SL model takes into account both the operational efficiency and traffic safety. To encompass all possible traffic conditions during each control period, the control model employs traffic flow relations calibrated from historical data to estimate the speed and density data with available volume under possible traffic scenarios. The performance of the proposed TOD SL control has been evaluated with the simulation experiments and compared with the other speed control strategies based on the selected measures of effectiveness.