Solutions to the traffic snarl: better information—and the means to deliver it—underpin USDOT's efforts to ease congestion through operational and technological improvements

Public Roads, July-August, 2007 by Rich Taylor

Approximately half of all congestion can be traced to recurring causes such as physical bottlenecks. The other half stems from nonrecurring causes, such as crashes, work zones, and weather. In May 2006, the U.S. Department of Transportation's (USDOT) National Strategy to Reduce Congestion on America's Transportation Network (also known as the Congestion Initiative) noted that "we have a significant short-term ability to mitigate the impacts of congestion and provide critical additional capacity during peak traffic periods by more effectively addressing these factors."

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If transportation managers can manage these recurring and nonrecurring conditions successfully, in a practical sense, capacity will be optimized, thereby creating a more efficient system. This optimization of existing capacity is becoming increasingly important as financial and other limitations constrain the addition of new physical capacity.

Reducing delays due to incidents, work zones, and poorly timed traffic signals is possible through an array of strategies and tools currently available. One of the primary focus areas of the Congestion Initiative is promoting operational and technological solutions, such as 511 traveler information, traffic incident management, work zone mobility, and traffic signal timing. USDOT identified these practice areas as offering the highest probability for generating significant benefits quickly and targeted them for greater attention and accelerated deployment in the action plan for rolling out the Congestion Initiative. Collectively, these practices provide operators, planners, decisionmakers, and travelers with information that allows for more informed decisions, better coordination, and quicker actions that can help avoid and reduce traffic congestion.

With the goal of deploying these technologies and practices broadly across the country, the Federal Highway Administration (FHWA) and State and local transportation officials are building on early successes and demonstrating the potential for significant benefits to national mobility.

Real-Time Traveler Information

At the heart of these technological solutions and operational strategies, approaches, and policies is real-time traveler information, which is essential to addressing both recurring and nonrecurring congestion. Real-time traveler information is information that enables travelers to decide how they will use (or not use) the transportation system. Agencies use the information to better manage and improve the system.

Real-time information enables motorists to manage the uncertainty of travel during congested conditions by leaving earlier or later, taking an alternative route, or even postponing discretionary trips. In fact, according to Transportation Analysis Fellow Karl Wunderlich at Noblis, coauthor of the FHWA report On-Time Reliability Impacts of Advanced Traveler Information Services (ATIS), Volume III: Implications for ATIS Investment Strategies, "Users of traveler information services who can vary their departure times by as little as 5 minutes on either side of their normal departure times can reduce late arrivals by up to one-third or more."

Another key benefit is more predictable travel, knowing what to expect before travel begins. Timely and accurate information about traffic incidents, weather, construction, transit, and special events helps improve the predictability of travel times and ultimately may help reduce the time spent driving in congestion. In a Washington, DC, case study in the aforementioned report, users reduced "late shock" (expecting ontime arrival prior to travel but arriving late) by more than 80 percent. By adapting trip decisions to the latest conditions, users of traveler information can cut significantly the amount of time they need to add into their trips due to the possibility of encountering backups from rush hour traffic, a crash, or some other tieup.

FHWA is pursuing three key activities under the umbrella of real-time traveler information:

* Facilitating deployment of 511 traveler services

* Encouraging the display of travel times on dynamic message signs (DMSs)

* Establishing and supporting a real-time system management information program, as called for in section 1201 of the Safe, Accountable, Flexible, Efficient Transportation Equity Act: A Legacy for Users (SAFETEA-LU)

Although each of these areas provides benefits individually, the real contribution will come from the synergy of all three. For example, addressing the section 1201 requirements can provide the data necessary to support new or enhanced 511 services and provision of travel times on DMSs, and the capabilities of the private sector could support section 1201 requirements and 511 travel times.

511 Traveler Information Services

The Federal Communications Com-mission designated the three-digit telephone number 511 for traveler information services provided by public transportation agencies throughout the United States. Now, 6 years into the program, almost 40 percent of the U.S. population is covered by 511 services. FHWA is striving for implementation of 511 services in all 50 States by 2010, a goal set by the U.S. Congress in SAFETEA-LU.