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Public Roads - November/December 2004

November/December 2004
Issue No:
Vol. 68 No. 3
Publication Number:
Table of Contents

Putting Travelers in The Know

by Brandy Meehan and Bob Rupert

Providing motorists with real-time traveler information is a key way that road managers can help motorists deal with the growing traffic congestion on the Nation's highways.

(Above) Disseminating real-time traveler information could help reduce the frustration and stress for motorists like this one stuck on a congested roadway.

According to the Texas Transportation Institute (TTI), unexpected congestion has a significant impact on motorists' attitudes. In its 2001 report, Traffic Congestion and Travel Reliability: How Bad Is the Situation and What Is Being Done About It?, the institute found that travelers want to know what to expect and almost always respond positively to accurate traveler information.

To generate real-time traveler information, traffic managers use intelligent transportation system (ITS) technologies to collect data on traffic volumes, queue lengths, speeds, and travel times. By combining these data with information gathered from highway service patrols and public safety response centers, managers can help ensure that motorists receive the most up-to-date, accurate, and high quality information.

"Delivering traveler information in real time has the potential to improve the driving experience, both by decreasing stress levels for motorists and improving the reliability of travel times," says Associate Administrator of Operations Jeff Paniati at the Federal Highway Administration (FHWA). "Many public agencies and private companies count on real-time traveler information to improve system performance, ensure customer satisfaction, and help make businesses profitable."

Access to up-to-the-minute information about traffic incidents, travel times along major corridors, and route-specific weather conditions can help motorists make more informed decisions and have more control over their trips. Public agencies and private companies have been providing traveler information for more than 20 years, but new ITS infrastructure and emerging technologies promise to broaden the amount and quality of real-time information available in the future.

Reducing Stress

Knowing how long a challenging situation may last often helps people cope with the situation, even if their options are limited and the situation is not expected to improve quickly. When the power goes off, for example, simply knowing what caused the outage and when the problem might be fixed can put peoples' minds at ease. Traveler information can work the same way.

Route-specific, real-time traveler information provides drivers with choices that could improve their travel times or at least provide a level of confidence in understanding the cause of the problem. Even if a traffic delay is unavoidable, motorists will know the severity of the situation and when it is likely to improve.

In most major metropolitan areas, commuting to work is becoming increasingly time-consuming and stressful for drivers. The 2004 Urban Mobility Report published by TTI in September 2004 cites that the average annual delay per peak traveler has gone from 16 hours in 1982 to 46 hours in 2002, or nearly tripled in the last 20 years. Total delay over the same period went from 0.7 billion hours to 3.5 billion hours.

In 2000, a marketing survey of 800 Minnesota households found that 66 percent of respondents thought the stress associated with traffic congestion was more difficult to deal with than a longer commute time. "People are experiencing more stress due to increased congestion and they want something done," said former Minnesota Department of Transportation (DOT) Commissioner Elwyn Tinklenberg in response to the survey.

Many transportation professionals agree that real-time traveler information can decrease the amount of stress associated with driving. A survey of Seattle-area users of the Washington State DOT traveler information Web site found that nearly three-quarters of respondents agreed that access to the site had reduced the stress of traveling in the metropolitan area. FHWA is sponsoring further research into the contribution of traveler information to reducing drivers' stress. Specifically, the research will model driver behavior to determine the value of traveler information in reducing stress. The results will be published in 2005.

Mobility Benefits

In addition to relieving stress, realtime traveler information also can produce measurable mobility benefits. According to FHWA research, more than 68,400 kilometers (42,500 miles) of highways in the United States experienced congestion in 2000. When traffic volume is near or exceeds capacity, the slightest incident can cause major backups and unexpected delays.

Travelers are accustomed to certain levels of congestion during their weekday commutes, but variability in travel times can cause inefficiencies for commuters, business travelers, and commercial vehicle operators. Without accurate and timely travel information, commercial vehicle operators risk falling behind schedule, and commuters have to build in extra travel time to ensure that they arrive at their destinations on time. This leads to wasted time and frustration.

A recent U.S. Department of Transportation (USDOT) study of advanced traveler information systems (ATIS) found that the potential benefits of traveler information are greatest in cities with the most day-to-day network variability. The study also found that in all cases, pretrip traveler information was highly beneficial. Motorists using traveler information in Cincinnati, OH, for example, reduced late arrivals by 37 percent, early arrivals by 91 percent, and early and late schedule delays by 30 and 69 percent, respectively. Just-in-time arrivals increased by 17 percent.

A study in the Washington, DC, area showed similar benefits. Commuters who did not use traveler information were three to six times more likely to arrive late.

Real-time information can help travelers know what to expect along their routes and therefore make more informed decisions before or during their trips. They can decide to stay the course, alter the departure time, choose a different route, or use an alternate mode of transportation. Regardless of the decision, the control is in the travelers' hands.

Collecting Appropriate Data

The key ingredient for traveler information is adequate real-time data at the appropriate level of accuracy. To generate useful information for travelers, managers need to process, synthesize, and compare the realtime data with historical data. But how much data are necessary? And what level of accuracy is required?

This map shows the extent of 511 deployments in the United States. In mid-2004, nearly 20 percent of the population could access traveler information through 511.

According to a 2002 FHWA survey of ITS deployments, about 30 percent of metropolitan areas in the United States provide real-time traveler information to the public. These areas have vastly different levels of data collection and surveillance on freeways and principal arterials. On average, real-time traffic data are collected on about 30 percent of freeway miles in the 78 largest metropolitan areas. The report Understanding Key Tradeoffs for Cost-Effective Deployment of Surveillance to Support Advanced Traveler Information Systems (ATIS), published from a study by FHWA in 2004, estimated that 50- to 60-percent network coverage is ideal, considering deployment and operating costs and expected benefits.

Of course, extensive coverage does not ensure accurate data. The quality of the data gathered by loop detectors installed in roadways depends on many factors, including maintenance, calibration, type of detector, and detector spacing. The FHWA report also found that most systems operate with a travel-time error of about 20 percent. The same study also concluded that an error level of 20 percent was the maximum acceptable for travelers to receive any benefit from using an ATIS.

FHWA research has found that data quality is an issue that impedes dissemination of real-time traveler information. Although most major metropolitan areas collect data on travel times, many traffic managers do not trust the quality of the data reported by their traffic management systems enough to provide the information to travelers. To address this problem, USDOT is developing guidelines for quality metrics that State and local highway agencies can use to improve their confidence in traffic data. The guidelines should be available by spring 2005.

Model Deployment in Arizona

In 2002, USDOT partnered with the Arizona DOT to deploy a model 511 system as an example of a traveler information service that advances content quality and features smooth interactions between callers and the 511 service. Slated for completion in 2005, the model deployment will illustrate how the innovative application of technologies can create an effective 511 service that delivers high-quality traveler information. The project will enhance the existing statewide 511 system operated by the Arizona DOT, help USDOT shape its approach to 511 services, and guide other States toward implementing successful programs.

Arizona's automated system encompasses a range of traveler information, including recurring traffic congestion, construction projects, weather conditions collected from snow and ice sensors installed along roadways, and the status of traffic incidents collected from regional incident management programs. The system also covers multiple travel modes, such as schedules and service interruptions for public transportation.

The 511 model deployment goes beyond providing basic traveler information by adding travel times for key arteries, information targeting commercial vehicle operators, and parking and airport information. Arizona DOT and its partners implemented a voice responsive, customer-designed interface between callers and the 511 system. A primary goal is to create an easy-to-use system that does not compromise callers' expectations for personalized information.

In March 2003, USDOT selected the Florida DOT to participate with FHWA in a model deployment, known as the Surface Transportation Security and Reliability Information System Model Deployment. The project is designed to implement a complete information infrastructure covering freeways in the Orlando metropolitan area and nearly 50 percent of the principal arterials. The model deployment, dubbed iFlorida, will serve as a test bed to help traffic managers better understand the optimal amount of network coverage for enacting transportation management strategies and improving traveler information.

A variety of techniques will be used to collect information, including using vehicles as probes. The Orlando area's existing traveler information service will be expanded from 5 to more than 240 segments, and information will be disseminated through the 511 traveler information telephone number and statewide Web site. Information on travel times and delays also will be displayed on dynamic message signs in the area.

"Once completed and evaluated, the iFlorida model deployment will offer valuable insights into the amount and quality of information necessary to provide real-time traveler information in a metropolitan area," says Toni Wilbur, director of Operations Research and Development at the FHWA Turner-Fairbank Highway Research Center.

Getting the Word Out

After generating, collecting, and analyzing the data, the next important step is for traffic managers to disseminate the information to the public. Of the 78 largest metropolitan areas in the United States, only 27 percent of representative agencies provided that traffic information to the public in 2002.

Agencies have at their disposal many methods, both private and public, to provide motorists with traveler information. Most people get traffic information from television and radio reports, which often are fed by traffic content providers in the private sector.

Another growing source for traffic information is 511 telephone services. The Federal Communications Commission designated 511 as the national traveler information number in July 2001. The following June, the first 511 system began operating in northern Kentucky and the Cincinnati, OH, metropolitan area. Since then, the number of 511 systems deployed across the country has grown steadily.

As of October 2004, 24 locations had launched services, including 17 statewide systems, 6 metropolitan systems, and 1 regional service. All told, the systems in operation today provide traveler information accessible by almost 25 percent of the Nation's population. By the end of 2005, another 13 States and 2 metropolitan areas expect to launch 511 services, extending the reach of the three-digit number to nearly 50 percent of the population.

Nationally, 511 usage continues to grow, with most systems noting monthly increases in call volumes. On average, more than one million calls per month are made to 511 systems, and FHWA expects this number to grow as additional systems come online and more people become aware of the service. Peak call volumes often coincide with poor weather, incidents, and other special events.

Research indicates that public demand for and use of telephone services for traveler information increases when systems use 511 instead of other numbers. Systems that have converted existing telephone numbers to 511 have experienced a 300- to 500-percent increase in call volume.

Studies also show that the increase in using the 511 service is accompanied by a generally high level of customer satisfaction. A customer satisfaction survey in San Francisco, CA, for example, reported that 90 percent of respondents were satisfied with the 511 service. The Montana DOT received similar results for its 511 service.

Dynamic message signs (DMS) are another highly visible way to disseminate traveler information. According to USDOT's "ITS Deployment Tracking" Web site, more than 2,800 permanent dynamic message signs have been deployed in 71 metropolitan areas, and nearly 700 portable signs are in use in 60 metropolitan areas. These signs can relay real-time traveler information in the form of travel time or delay messages.

In Atlanta, the Georgia DOT uses dynamic message signs along limited- access highways to provide information such as travel times to freeway interchanges or other points of interest. The iFlorida model deployment in Orlando will use these signs to provide motorists with travel times between points along alternate roadways, giving drivers information to help them choose optimal routes.

Georgia DOT displays real-time travel information on dynamic message signs like this one in the Atlanta metropolitan area.

Despite the number of signs deployed nationwide, an informal FHWA survey found that only a handful of areas were posting messages about travel times on their signs. In a July 2004 policy memorandum, FHWA described recommended practices for dynamic message signs, including posting travel times. Although travel times may not be appropriate for every city, they have proven to be successful in regions or corridors that experience periods of recurring congestion—congestion generally resulting from traffic demand exceeding available capacity and not caused by any specific event such as a traffic incident, road construction, or a lane closure.

"FHWA strongly encourages State and local agencies to put travel times on dynamic message signs and has developed guidance toward that end," says Associate Administrator Paniati. "In metropolitan areas and congested corridors, our goal is to make it unacceptable to have 'dark' dynamic message signs—ones that are not being used regularly to provide travel times—and to ensure that travelers everywhere can access 511 for real-time traffic, transit, and weather information."

Online Travel Information

The Internet is another way that highway agencies and private companies provide traveler information. Nearly 300 Web sites in the United States update motorists about construction, road closures, major incidents, and tourism in map-based formats. Real-time information is provided to the extent available.

The sophistication of these sites varies greatly, and each year, FHWA recognizes those deemed most outstanding. In 2003, FHWA honored the Georgia DOT's "Navigator" site, the Washington State DOT's "Statewide Traveler Information" site, the Kentucky Transportation Cabinet and Indiana DOT's "TRIMARC" site, and the "GCM Travel" site, a cooperative effort among the Indiana, Illinois, and Wisconsin DOTs to address traffic in the Gary-Chicago-Milwaukee areas.

FHWA applauds the Georgia Navigator site as one of the Nation's most advanced. Accessible at, the site features a State map, multiple camera views, customized information on travel times, major travel alerts, and weather information.

To ensure that the site continues to meet the needs of users, the Georgia DOT surveys visitors regarding the site's features, when and how often they access the site, and whether the information helps them alter their routes or modes of transportation. "The ability to get trip times is a popular area of the site," says Mark Demidovich, assistant State traffic operations engineer at Georgia DOT. "You click on your starting and stopping points on the map, and the system calculates the travel time and average speed for you."

The Georgia "Navigator" Web site offers camera views, major travel alerts, and customized traffic information from across the State.

New enhancements include "My Navigator" personalized homepages and the capability to receive information on mobile devices, such as personal digital assistants and cell phones. "The 'My Navigator' feature allows you to set up your own profile so that every time you come back to the site your favorite features—maps, cameras, trip times—are all presented on one page," Demidovich says. "It's a real time saver."

The Washington State site, available at, continues to receive favorable feedback from users. "When we launched a new version of the site in February 2004, we thought the reaction would be 'I can't believe you're changing it,'" says Laura Merritt, Washington State DOT's interactive communications manager. "Instead, we're getting, 'It's even better than before; thank you for providing such a valuable service.'"

The site averages about 50 million page views a month, but in one peak month—January 2004—the site registered 115 million page views. "We had 12 million page views in 1 day during a statewide snowstorm," Merritt says.

The redesign, based on customer feedback, makes it easier for users to access information. The site now includes one-stop shopping for travel alerts and slowdowns, and more than 300 real-time camera images. "Before, users had to go to different pages to find what they needed," Merritt says. "Now they can find anything that impacts travel in one place—whether it's construction, an incident, or the weather." In the future, the site will feature e-mail alerts, and users will be able to personalize their information.

The Kentucky Transportation Cabinet and Indiana DOT developed TRIMARC (for Traffic Response and Incident Management Assisting the River Cities) to provide travelers with information on the interstate highway system in the greater metropolitan area of Louisville, KY, and southern Indiana. The site,, complies with accessibility standards and counts ease of use among its keys to success. Developers studied other traveler information Web sites and designed TRIMARC with a feature that enables users to click on signs or cameras to access more detailed information. A recent enhancement, invisible to users, automatically updates the area's 511 system as new material is posted on the Web.

The Indiana, Illinois, and Wisconsin DOTs cooperatively developed the "GCM Travel" site, at, using a state-of-the art data-sharing system featuring a Common Object Request Broker Architecture (CORBA®) interface. With this system, users can link to information across the entire tristate priority corridor, including cameras, traffic maps, and messages posted on dynamic message signs. New features include real-time information on the Illinois Tollway, a link to transit information on the congestion map, and links to Chicago-area airports. In the future, data gathered from sensors in northwestern Indiana will be added, making more information available to emergency service providers and adding real-time information on transit.

Looking Toward the Future

Although real-time traveler information already benefits users in several metropolitan areas, many experts at FHWA and elsewhere believe the full benefits are yet to be seen. Current traveler information is limited to data collected primarily by loop detectors and video cameras along limited access highways in major metropolitan areas. The most effective realtime traffic information service provides traffic conditions on both primary and alternate routes so drivers can make truly informed decisions. But this requires complete and accurate data for all major routes.

The Washington State DOT's "Statewide Traveler Information" site provides real-time traffic and weather conditions, as well as travel alerts and slowdowns (top). The site uses colors to illustrate the level of congestion on various segments of roadway, as shown on this screen capture showing the Puget Sound area (bottom).

Innovative techniques for data collection are emerging that may provide the level of coverage necessary for traveler information. One technique is to use mobile communications devices to gather information on traffic for the entire transportation network. Private firms can collect the data and make them available to operating agencies, information service providers, and others.

USDOT and Virginia DOT are partnering on a study to test the feasibility of deriving traveler information from cell phones. If successful, the technology could help provide information on travel times on a variety of roadways, including freeways and major arterials.

The Vehicle Infrastructure Integration initiative—cosponsored by USDOT, the American Association of State Highway and Transportation Officials, and several major automobile manufacturers—is exploring the concept of communication and data exchange between vehicles and the roadside. Relevant data that could be collected and transmitted by vehicles include speed, windshield conditions, air temperature, sudden braking, and more than a dozen other indicators. "Although still in the exploratory phase, the concept of using vehicles as data collection probes is gaining momentum," says Associate Administrator Paniati.

The "TRIMARC" Web site, which provides traveler information for the interstate highway system in the greater Louisville, KY, and southern Indiana metropolitan area, enables users to view current messages displayed on dynamic message signs throughout the region, as shown here.
The "GCM Travel" Web site disseminates traveler information to motorists in the Indiana, Illinois, and Wisconsin area through a state-of-the-art data-sharing system.

The Commute Atlanta project, sponsored by FHWA, Georgia DOT, and the Georgia Institute of Technology (Georgia Tech), is studying the use of vehicle probes to collect travel data to provide better information on where, when, and under what conditions people drive in Atlanta. Using volunteer test vehicles, researchers installed devices that track travel patterns and monitor vehicle and engine operations. Data are sent back to Georgia Tech via cell phones using data-only connections, where researchers will try to identify recurrent traffic congestion.

Finally, according to the USDOT survey Advanced Traveler Information Service (ATIS): What do ATIS Customers Want?, conducted in 2000, travelers want reliable, accurate, and relevant traffic information while they drive. Survey respondents said they wished they could press a button when approaching congestion or a route choice and find out which option offered the least congestion.

The use of wireless communications to provide location-based services in vehicles is a growing technology with the potential to meet travelers' demands for traffic information delivery. Currently used mostly for navigation and emergency services, this technology is often included in luxury vehicles or as an option in midlevel vehicles. As prices fall over the next 5 years, FHWA expects the demand for both in vehicle devices and aftermarket units to increase. These wireless services, coupled with ubiquitous traffic information, may give travelers the "button" they seek.

Real-time traveler information is important to motorists, particularly when faced with increasing congestion in which the slightest traffic disruption can have a significant impact on mobility. Combined with 511 services, dynamic message signs, traffic Web sites, and invehicle dissemination methods, transportation managers increasingly will be able to offer travelers high-quality, real-time information.

Brandy Meehan is a transportation specialist in the FHWA Office of Transportation Management. She currently works on real-time traveler information and vehicle infrastructure integration programs. Meehan holds bachelor's and master's degrees in civil engineering from the University of Tennessee.

Bob Rupert is the traveler information team leader in the Office of Transportation Management, part of FHWA's Office of Operations. He manages the traveler information program and serves as program manager for the 511 telephone number. Previously, Rupert managed the Travel Technology (TravTek) operational test of invehicle navigation in Orlando, FL, and led several other ITS projects dealing with traveler information.

For more information on FHWA's real-time traveler information program, visit