Book excerpt: The concept of real-time performance measurement analyzes feedback from the operational response to freeway incident conditions and provides a quantitative methodology for assessing the impacts of various operational strategies. The significance of this technique is that it can enhance the efficiency of freeway incident management. Even a small percent reduction in the length of an incident would accrue millions of dollars of time-savings for the affected portion of the roadway. The design and construction of a real-time performance measurement system require an understanding of the performance measures and their application to transportation, a review of the state-of-the-practice in performance measurement, and an experimental design on which to build a prototype system.