Overview
The SHRP 2 Reliability program aims to improve trip time reliability by reducing the frequency and effects of events that cause travel times to fluctuate in an unpredictable manner. Congestion caused by unreliable, or non-recurring, events is roughly as large as congestion caused by routine bottlenecks. Non-recurrent events such as crashes, work zones, special events, and weather disrupt normal traffic flow by causing reduced speeds, lane closures, and erratic driving maneuvers. The goals of the Reliability focus area target travel time variation – that characteristic of the transportation system that means one must allow an hour to make a trip that normally takes 30 minutes. This transportation system characteristic is important for travelers and shippers, and is also a component of the congestion problem in which transportation agencies can make significant and measurable gains even as travel demand grows. Reducing delay related to reliability has the added benefit of reducing primary and secondary crashes, vehicle emissions, fuel use, and other benefits.
A key component to addressing the reliability issue related to urban mobility is conveying reliabilityrelated information to system users so that they can make informed decisions about their travel. The challenge for transportation professionals lies in selecting the best means of conveying that information so that it is usable and effective. The goal of the L14 project is to examine what combination of words, numbers, symbols, layout, lighting, color, and spacing of user information messages along with communications channel and technology platform best communicate information about travel time and reliability to travelers so that they may make optimal travel choices from their point of view. Such choices include whether to take a trip or not, departure time, mode choice, and route choice.