The National Academies

SHRP 2 L14 [Completed]

Traveler Information and Travel Time Reliability

  Project Data
Funds: $1,088,754
Research Agency: Texas A&M
Principal Investigator: Beverly Kuhn
Effective Date: 9/1/2009
Completion Date: 3/31/2013

Project snapshot. More details below.

(Project Number)
Impact on Practice
Product Status

A lexicon that describes how transportation agencies can best communicate information about travel time reliability to motorists so they can make informed decisions and better plan to arrive at their destination on time.
With better public awareness and understanding of the variability of travel time, road users can quickly learn to work around nonrecurring delays due to incidents, bad weather, work zones, special events, and malfunctioning traffic control devices. This type of behavior can reduce delays on the system and improve performance.
The lexicon is available at https://www.trb.org/Main/Blurbs/168810.aspx and the final report is available at https://www.trb.org/Main/Blurbs/168809.aspx.

Responsible Staff: William Hyman and Abdelmename Hedhli
Travel time reliability information includes static data about traffic speeds or trip times that capture historic variations from day to day, and it can help individuals understand the level of variation in traffic. Unlike real-time travel time information, which provides a current snapshot of trip conditions and travel time, reliability information can be used to plan and budget in advance for a trip. Travel time reliability information can improve urban mobility by conveying reliability-related information to system users so that they can make informed decisions about their travel.
This project had six objectives:
  1. Better understand the current and near-term future dimensions of the travel time reliability information marketplace, including technologies, the roles of the public and private sectors, and choices (both free and priced) available to travelers.
  2. Better understand what network travel time and travel reliability information travelers require, particularly in complex metropolitan environments where many travel choices are possible. Better understand how travelers would use improved information.
  3. Determine how best to communicate travel time reliability information to travelers so that they can understand it and use it to make optimal travel choices. Develop a guide to help providers of traveler information ensure that information regarding travel time reliability is offered in a manner that is most useful to travelers.
  4. To the extent possible, quantify the potential for improvements in the communication of travel reliability information to affect traveler choices such that positive impacts on system performance occur (e.g., improved transportation system reliability).
  5. Develop a simple and easily standardized lexicon for communicating travel time reliability concepts among transportation professionals and travelers.
  6. Develop prioritized, near-term strategies for improved dissemination of travel time reliability information and provide guidance for state departments of transportation and other public sector transportation agencies that are contemplating providing travel reliability information to travelers.
This project developed A Lexicon for Conveying Travel Time Reliability Information and a Final Report. The Lexicon is intended to provide recommendations on appropriate ways to introduce and provide travel time reliability information to travelers so that such information is most likely to be understood and used by travelers to influence their travel choices, while not presenting a safety hazard in the process. This document was based on results from a series of human factors experiments and the development of a utility function, with input from a literature review, expert interviews, and a technology and innovation scan.
The Final Report documents this research project. A literature review was conducted to document existing practices and lessons learned regarding the communication of both travel and other related reliability information. Expert interviews and a technology and innovation scan further examined the state of the practice in communicating information to travelers. A series of human factors experiments, including focus groups and surveys, assessed travelers’ 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.
Status: This project is complete.
Product Availability: A Lexicon for Conveying Travel Time Reliability Information is available at https://www.trb.org/Main/Blurbs/168810.aspx, and Effectiveness of Different Approaches to Disseminating Traveler Information on Travel Time Reliability (the Final Report) is available at https://www.trb.org/Main/Blurbs/168809.aspx.

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