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InTransition Magazine : Transportation Planning, Practice & Progress

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Technical Toolbox

Traffic Probes Provide Real-Time Data on Road Conditions

By Eric Goldwyn

About Technical Toolbox

  • Technical Toolbox highlights innovations and emerging technologies making an impact in the transportation sector.

Dash Navigation sells monitors that use traffic probe data

to help motorists to determine the best driving routes.

If you’ve glided through an E-ZPass booth in North Jersey or cruised a local highway with a cell phone turned on lately, your movements may have been tracked. But don’t worry—experts say the information you provided was anonymous and could have actually sped up your trip.

Traffic probe technology has the ability to supply vast quantities of accurate real-time data that describes road conditions, origin-destination information and travel time statistics. This data can help drivers dramatically improve their commuting times by offering fresh information on delays and faster alternative routes. The technology also has the potential to help planners and policymakers make better-informed decisions in the future about where to build extra capacity or when to close a specific route for construction.

Transportation probes can take many different forms, but one main principle remains constant: They anonymously aggregate large amounts of information by constantly uploading the position of cars within a fixed network.

One probe technique being used in the New York metro area tracks road conditions by accessing positioning data via E-ZPass identification tags. E-ZPass is an electronic toll collection system that allows drivers in several East Coast states to prepay tolls and attach a small electronic device to their vehicles. Tolls are automatically calculated and deducted from the accounts as customers pass through the toll lanes. To capture a complete picture of traffic conditions, antennas that read E-ZPass tags have been installed on nearly 1,000 miles of highways and parkways in both New York and New Jersey to anonymously track vehicles.

“Once the personal data has been stripped from the tags, this data is used to compute travel times and speeds,” said Tom Batz of TRANSCOM, a coalition of transportation and public safety agencies in the New York/New Jersey/Connecticut region established to coordinate regional transportation management.

With this data, transportation agencies can accurately extrapolate the distribution of traffic on different roadways, identify the effects of accidents and inform drivers about alternative routes by transmitting messages to roadside displays, according to Batz. One of the great benefits of the data is that it allows transportation professionals to communicate with drivers as data becomes available, he said.

An example of this technology in action appears at the approach to the George Washington Bridge. As drivers near the entrance, electronic signs flash continuously updated estimated travel times for the upper and lower decks of the bridge. This information cues drivers to select the quicker route, which helps normalize the bridge’s traffic flows and reduce heavy congestion on either deck, according to Batz. In this instance, traffic information is immediately sent back out to the road to improve a driver’s ability to make an informed decision, he said. TRANSCOM also makes its data available for radio traffic reports and highway advisory radio systems.

Cell Phones as Beacons

A newly emerging probe strategy promoted by private companies and marketed to both individual drivers and transportation agencies compiles traffic data using mobile phone networks and the Internet. Companies like Intellione and AirSage gather traffic data by tapping into existing mobile networks that provide phone and data service. When cell phones search for service, they communicate with nearby towers, and with the help of proprietary algorithms, these signals can be translated into basic traffic information and positioning data.

These companies can calculate traveling speed and positioning data by tracking a phone in a vehicle—it need not even be in use, but must be turned on. By transforming a mobile phone into a transportation beacon, private companies can achieve similar results to the probe strategy that employs E-ZPass identification tags without installing the costly infrastructure.

In October, the Georgia Department of Transportation (GDOT) hired Atlanta-based AirSage to provide data on traffic conditions along hundreds of miles of roads in the Atlanta-Macon corridor. GDOT officials hailed the arrangement as an affordable way to gather a body of information in a few months that might have taken a decade by other means.

“GDOT had an extensive network of video-based sensors in and around the metropolitan Atlanta area, however, we were fairly blind when it came to monitoring other roadways around the state,” said Mark Demidovich, GDOT’s assistant state traffic engineer. “We were looking for a quicker, lower-cost solution other than laying hundreds of miles of fiber and thousands of detection units.”

AirSage has an exclusive long-term, nationwide contract with Sprint Nextel that provides them access to anonymous information supplied by over 50 million cell phones nationwide, according to Vice President of Sales and Marketing Tom Bouwer. The company collects, organizes and distributes that information to clients such as GDOT, which can then provide advisories about jams and alternate routes to drivers through means like highway advisory radio bulletins, message signs or Georgia NaviGAtor (, the agency’s traffic information Web site.

“People are now looking for anything, whether its flextime [at work] or alternate routes, to avoid being stuck in traffic,” Bouwer said.

The demand for these services would seem to back that up. Bouwer said that when he first started at AirSage two years ago, his job involved plenty of cold calling and trying to sell people on a product they didn’t understand, but today “the phone rings all day with people who want our data.” The Wisconsin Department of Transportation reached a two-year agreement with AirSage in April for traffic information pertaining to Interstate 94 and two primary alternative routes that serve as major trucking arteries between Milwaukee and Madison. Bouwer said about 50 cities are AirSage subscribers now, and he anticipates that number will jump to between 75-100 in 2008.

“I think by next year, it will be a lot more widespread. I don’t think we need to look 15 years down the road,” Bouwer said.

Marketing to Individual Drivers

Rather than targeting transportation departments, Dash Navigation markets a sleek in-dash monitor, the Dash Express, directly to drivers. While these products resemble GPS units that display positioning information and turn-by-turn directions, the Dash Express connects to the Internet and offers helpful search options that range from nearby restaurants and gas stations to the more sophisticated customized maps that the driver can design.

“But the real advantage that the Dash Express has over its competitors stems from its ability to create a powerful network in which each device acts like an anonymous probe that automatically reports traffic conditions back to the Dash Driver Network,” company spokeswoman Gina Aumiller Bender said.

By sharing traffic information with the Dash Driver Network, Dash can calculate travel times and speeds and provide detailed information about specific routes, she said. The Dash Express, she said, shifts the benefits from the public agencies and authorities directly to its customers by providing them with real-time traffic data. The Dash customer then has the ability to predict accurately travel times, evaluate the road conditions on alternate routes and make smarter decisions, she said.

This information aims to help ease congestion and normalize the flow of traffic by prompting drivers to take advantage of timesaving tips that promote the efficient allocation of the road. While the strength of the Dash system relies on the number of users that transmit data back to the network, it also incorporates available historical travel data to supplement the gaps in its growing network, according to the company.

As the use of transportation probe technology grows, experts say planners will have access to vast quantities of accurate and current information without having to rely on flawed and outmoded data collection practices. Government officials will be capable of providing detailed statistics to draw support for transportation projects by clearly demonstrating the need for added capacity, and drivers will be able to accurately predict when they’ll arrive at their destination and see if a faster route exists. Combined, all of these advantages may enable officials to target the projects most in need of the limited funds available and generate meaningful savings by reducing overall travel times.

“DOTs can now use this data for planning purposes,” Bouwer said. “Where do we see congestion increasing? Where should we build a new highway? How can we change our infrastructure to accommodate the needs of today’s drivers?”

Eric Goldwyn received a master's degree in urban planning from the NYU-Wagner Graduate School of Public Service in 2007.

Staff writer Karl Vilacoba contributed to this story.

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