The objective of this project is to identify and evaluate strategies and tactics intended to satisfy the travel-time reliability requirements of users of the roadway network — those engaged in freight and person transportation in urban and rural areas. The basic causes of unreliable travel times are an imbalance between demand and capacity and the congestion that results from too much demand for a given level of capacity. Once congestion forms, travel times become more variable (less reliable) and thus less predictable. Moreover, congested facilities do not have the resilience to accommodate unexpected travel interruptions, leading to flow breakdowns and serious degradation of reliability. The types of solutions that can be brought to bear on the demand/capacity imbalance depend on whether congestion can be anticipated or whether congestion results from unexpected events. Where volume routinely approaches and/or exceeds capacity (recurring congestion), demand management and capacity increases are likely to be effective in improving reliability. In locations where unexpected disruptions cause the majority of congestion (non-recurring congestion), techniques that detect disruptions and facilitate rapid recovery from those events are more likely to be effective. A variety of technological changes, operational solutions, and organizational actions currently exist or will become available in the next 20 years. These changes, solutions, and actions will allow more effective management of transportation demand, increases in person and freight moving capacity, and faster recovery of the capacity lost due to various types of disruptions. A wide range of activities will be employed by groups ranging from individual travelers, carriers, and shippers, to highway agencies, local governments, and private companies that supply services that support roadway operations. Travel-time reliability will improve through the collection and use of more and better information, together with agency integration and adoption of shared goals. The application of that information can be used to balance and manage demand and transportation system (multi-modal) capacity more effectively. That means using information to actively expand capacity in those places where its value exceeds the cost of that expansion. At the same time, information needs to be provided to travelers so that they can make informed choices about their best travel option, given their own values of time and reliability. (Author/publisher)
Abstract