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Publication Number:  FHWA-HRT-10-002    Date:  Jan/Feb 2010
Publication Number: FHWA-HRT-10-002
Issue No: Vol. 73 No. 4
Date: Jan/Feb 2010


Internet Watch

by Alicia Sindlinger

Of the 1,917 miles (3,085 kilometers) that make up the entire length of I-95 stretching from Maine to Florida, more than 1,040 miles (1,674 kilometers), or 60 percent, are subject to regular heavy congestion. This statistic comes as no surprise to any traveler who has sat in traffic on I-95. To help motorists plan long-distance travel in ways that contribute to improving safety and easing traffic congestion along the busy interstate, the U.S. Department of Transportation (USDOT) is sponsoring a Web site that provides real-time travel times and traffic information. The "I-95 Corridor Travel Time Information" site is available at www.i95travelinfo.net.

"This Web site provides long-distance travelers of all types--commuters, truck drivers, intercity bus operators, tourists--a valuable resource for information on traffic conditions," says Stacy Unholz, a senior intelligent transportation systems specialist at PBS&J, which manages the Web site in cooperation with the University of Maryland. "Although there are other travel information Web sites, this is the only publicly available site that offers intercity and interstate congestion information and travel times for the I-95 corridor."

 The USDOT Research and Innovative Technology Administration launched the Web site at the Intelligent Transportation Society of America's annual conference in June 2009 as one of several research efforts in the Safe and Efficient Travel through Innovation and Partnerships in the 21st Century (SafeTrip-21) program. SafeTrip-21 is designed to improve safety and reduce traffic congestion by adapting existing technology for transportation needs. The Web site covers I-95 and other major roads that comprise the I-95 corridor, from Portland, ME, all the way to Orlando, FL.

The 'I-95 Corridor Travel Time Information' Web site (shown here)  provides real-time updates on traffic and travel times.

The "I-95 Corridor Travel Time Information" Web site (shown here) provides real-time updates on traffic and travel times.

Calculating Congestion and Travel Times

The Web site receives its traffic information from a leading provider of real-time, historical, and predictive traffic information, and also receives data from the largest global positioning system (GPS) probe network in the world. The automated data streams arrive from millions of GPS devices owned by long-distance commercial vehicle operators, shipping companies, intercity transit providers, and other suppliers. The data are analyzed and processed, and then provided to the Web site as real-time speed and travel time data.

When visitors interact with the congestion map on the Web site, the server that hosts the site interfaces with the data provider to receive and display congestion information. Similarly, when a user employs the travel time function and selects an origin and a destination location, the data provider's traffic servers return real-time estimates of the travel time between the two points.

Using the Site to Plan a Trip

When visiting the site, users see a map with congestion information for the entire coverage area. All covered roads are highlighted in colors that indicate traffic conditions: green for free flow (93 percent of the speed limit and above); yellow for moderate flow (63-92 percent of the speed limit); red for heavy congestion (32-62 percent of the speed limit); maroon for stop and go (31 percent of the speed limit and below); and black if the road is closed. In compliance with the Americans with Disabilities Act, there is an alternate color choice, "Color Blind," which switches the map colors to a set designed for users who are color blind to red and green.

To generate a route and see the estimated travel time, a user must select a departure location and destination. The system will provide an estimation of how long the trip should take, based on current conditions between the origin and destination; an estimated normal travel time, based on historical speeds and normal congestion for the time when the trip was estimated; total distance of the trip in miles; and a time stamp of the time the route was generated, which allows the user to confirm that the data are current. It is important to note that road conditions are always subject to change and that the travel time estimated at the beginning of the trip must be rechecked to remain valid and informative. In addition to traffic and travel information, the Web site provides links to more travel-related resources within the coverage area, frequently asked questions, and a user survey.

With access to this information on congestion and travel times, I-95 travelers can be more informed and prepared for their trips--saving time and money, potentially avoiding their own contribution to heavy congestion, and creating safer conditions.

Alicia Sindlinger is a contributing editor for Public Roads.



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