Definition and Measurement of Transportation System Performance

Problem

Performance measures are needed to help make decisions regarding the overall level of resources to devote to a transportation system, where to allocate these resources, and how best to use them.

Decisions regarding the level of resources and where to allocate these resources require regular monitoring of the system to reveal opportunities for improvement. The decision of how best to use transportation resources must be more carefully examined in order to evaluate multiple means of addressing transportation needs and their respective costs and benefits to the public.

Method

The overall goal of a transportation system is to maximize the benefit of the system over its costs. Performance measures should therefore relate benefits to costs.

Specific attention is given to intelligent transportation systems which have both the capability to deliver benefits to a transportation system, and the capability to generate useful data on vehicle-miles and travel time within a transportation network

Findings

The primary costs of transportation: time, money, property damage and injury, environmental degradation, and discomfort, such as the stress or delay caused by difficult driving conditions. Transportation system performance is measured in terms of the amount of transportation provided, which indicates the amount of access provided (person-trips, person-miles, and $-miles of freight), travel time (both the average and the variation), and the amount of property damage and injury, and public monetary costs. These are the primary determinants of overall benefits and costs. These determinants are measurable and they can be influenced by the actions of transportation agencies.

In order to provide useful data for routine transportation system performance assessment, the following is recommended:

• Limit the number of routine measures, to concentrate resources on the most useful measures.
• Continue research to improve methods for measuring volumes and travel times.
• Develop a prototype travel time and volume measurement system, including data collection, processing, and storage, and characterization of performance.
• Develop schedules for measuring performance that are appropriate for different traffic situations.