Improved Dynamic Message Sign Messages And Operations

Improved Dynamic Message Sign Messages and Operations

Evaluating Alternative Operations Strategies to Improve Travel Time Reliability

This report from the second Strategic Highway Research Program (SHRP 2), which is administered by the Transportation Research Board of the National Academies, sets out requirements for travel time reliability within a performance-based planning process. The research includes an effort to determine the economic value of improvements in travel time reliability by applying options theory from the financial sector. The report includes two succinct tables that describe requirements for person and freight trips for reliable transport, as well as a forecast of the year 2030 under alternative assumptions that may influence travel time reliability.

Advanced Notification Messages and Use of Sequential Portable Changeable Message Signs in Work Zones

In this report, researchers document the results of a laptop-based human factors study of alternative formats of presenting advance notice work zone information on portable changeable message signs (PCMSs) and a Texas Transportation Institute (TII) driving simulator study of the ability of motorists to capture and process information on two PCMSs used in sequence to convey information about upcoming traffic situations. Based on the studies, researchers recommend that messages that require the display of calendar dates for future roadwork and other traffic control activities should utilize a message format consisting of the three-character abbreviation of the month (e.g., APR for April) in conjunction with the date. When future work activities span several days all in the same month, the month needs be noted only once in the message (i.e., APR 21-23) rather than repeating the month (i.e., APR 21-APR 23). The ITI driver simulator study results indicate the need to keep overall messages at or below the four-unit maximum recommended in existing guidelines. Researchers found that presenting five units of information on sequential PCMSs resulted in low comprehension rates, below what would be acceptable for highway applications. However, by keeping the message length to four units, it does appear that the use of sequential PCMSs will result in comprehension rates comparable to those obtained by presenting the same information at a single location on a large dynamic message sign (DMS), and is recommended as an acceptable formatting approach for TxDOT. Comprehension may be enhanced by repeating one of the units of information on both PCMSs.