TRB’s second Strategic Highway Research Program (SHRP 2) Reliability Project L14 has released a prepublication, non-edited version of a report titled Effectiveness of Different Approaches to Disseminating Traveller Information on Travel Time Reliability that provides recommendations on appropriate ways to introduce and provide travel time reliability information to travellers so that such information can be understood and used in a way that influences their travel choices, but does not present a safety hazard. Reliability Project L14 also produced a report title A Lexicon for Conveying Travel Time Reliability Information (http://www.trb.org/Main/Blurbs/168810.aspx) that includes a glossary of terms designed convey travel time reliability information can be understood and used in a way that influences their travel choices, but does not present a safety hazard. The second Strategic Highway Research Program (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. 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 manoeuvres. The goals of the SHRP 2 Reliability Program focus on travel time variation–that characteristic of the transportation system that means the driver’s current trip will take much longer than normally expected. For example, a driver must allow an hour to make a trip that normally takes 30 minutes. This transportation system characteristic is important for travellers and shippers and is a component of the congestion problem in which transportation agencies can make significant and measurable safety and traffic operational improvements even as travel demand grows. Reducing delay related to reliability has the added benefit of reducing primary and secondary crashes, vehicle emissions, and fuel use, and yields other benefits. A key component of addressing the reliability issue related to urban mobility is conveying reliability-related information to system users so that they can informed decisions about their travel. This report documents the research conducted as part of SHRP 2 L14, Effectiveness of Different Approaches to Disseminating Traveller Information on Travel Time Reliability. A literature review was conducted to document existing practices and lessons learned regarding the communication of both travel- and non-travel-related reliability information. Expert interviews and a technology and innovation scan further examined the state of the practice in communicating information to travellers. A series of human factors experiments, including focus groups and surveys, assessed travellers’ comprehension of and preferences for various reliability-related words and phrases. Finally, two laboratory experiments developed a utility function for travel time reliability information by observing participants’ use of reliability information during simulated commute trips and soliciting their opinions regarding the monetary value of that information. The lexicon developed as the final task of this project is intended to provide recommendations on appropriate ways to introduce and provide travel time reliability information to travellers so that such information is most likely to be understood and used by travellers to influence their travel choices, while not presenting a safety hazard in the process. (Author/publisher)
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