摘要: Congestion on urban freeways impacts safety, motorist delay, air quality, andenergy consumption. In areas where travel demand far exceeds capacity, some level of congestion will be inevitable. However, where imbalances in the free... 展开 Congestion on urban freeways impacts safety, motorist delay, air quality, andenergy consumption. In areas where travel demand far exceeds capacity, some level of congestion will be inevitable. However, where imbalances in the freeway system exist, bottlenecks restrict the use of available capacity. Valuable capacity can be recaptured, congestion reduced, and impacts diminished if these bottlenecks can be removed. This research report defines bottlenecks, discusses methodologies for identifying and determining the cause(s) of a bottleneck, suggests appropriate ways to alter geometrics to diminish the impacts of a bottleneck, and provides a methodology to estimate the benefits to be expected from implementing a bottleneck improvement. Examples of implemented projects where before and after data have been collected are also discussed. 收起