Applicable Performance Measures
Applicable Performance Measures Three performance measures underpin this analysis methodology: average speed, percent followers, and follower density. Typical agency performance objectives for two-lane highways focus on reduced travel times and reduced pressure to pass (reduced percent and density of followers). The three performance measures were selected to represent the quality of service provided by two-lane highways because they most closely conform to typical agency performance objectives. They also have the advantage of being sensitive to the design and demand features typically considered when planning and designing two-lane highways.
Average Speed Average speed is a key performance measure for two-lane highways. The general relationship between average speed and flow rate.
Percent Followers The measure percent followers represents the freedom to maneuver and the comfort and convenience of travel. It can also serve as a proxy for the need to provide passing opportunities. Percent followers is the percentage of vehicles passing a given point on the roadway that are considered to be in a follower state. Being in a follower state is used as a surrogate to indicate a driver’s perception that they are being delayed by a slower driver. Higher values are generally indicative of restrictions in passing (very infrequent passing zones or passing lanes, high volumes in the opposing direction).
