This synthesis examined the use of performance measures for the monitoring and operational management of highway segments and systems. The current state of the practice includes a wide and varied approach to performance measures, with more than 70 performance measures identified in this synthesis. An assessment of the relative strengths and weaknesses of these measures was performed. The measures that were identified as being used the most successfully directly reported conditions experienced by the traveller, such as travel time, speed, and delay. Measures that are derived from these basic units, primarily indices, were found to be less relevant to the operational environment than to policy planners. Based on the results of the survey of state departments of transportation and metropolitan planning organizations, the dimensions of operational performance that were the most relevant were the quantity of travel and the quality of travel.