Design Guide for Addressing Nonrecurrent Congestion. The Second Strategic Highway Research Program.

摘要

The continuing growth of traffic congestion on the nation's highways is increasing the concerns of transportation agencies, the business community, and the general public. Congestion has recurring and nonrecurring components. Recurring congestion reflects routine delays during specific time periods where traffic demand exceeds available roadway capacity. Road users have come to expect these daily traffic patterns and adjust travel plans accordingly to achieve timely arrivals. Nonrecurring congestion, which comprises the majority of total congestion, results from random incidents that cause unexpected delays, such as crashes, weather, and work zones. Road users are frustrated by unexpected delays that can make for unreliable arrival times at their destinations. The delivery of travel time reliability is becoming an emerging business activity and performance measure for transportation agencies to meet the increasing expectations of the public and freight industry. The purpose of this guide is to give transportation engineers, designers, planners, and decision makers an understanding and technical reference on how different highway geometric design elements can be deployed, in new designs or site retrofit actions, to contribute specifically to the reduction of nonrecurring congestion and travel time reliability improvement on both urban and rural freeways. The guide introduces the nonrecurring and travel time reliability topics and metrics, a catalogue of design elements, and a process for selecting candidate design elements to evaluate for a specific site.