This October, transportation officials in the Dallas area will debut a new program known as Integrated Corridor Management (ICM) along U.S. 75, which extends 28 miles from the city to its northern suburbs. Under the program, all transportation assets in an area are treated as part of a single system. In other words, trains, highways, surface streets and so on will be taken into account when deciding how best to keep traffic flowing, especially when something goes wrong. "What you're going to experience is a more reliable trip, less congestion and less queuing," says Koorosh Olyai, who led the ICM project while assistant vice president for mobility programs development at Dallas Area Rapid Transit (DART). Olyai now works in the private sector for the firm Stantec, but continues to assist DART on the project.
Dallas was selected by the U.S. Department of Transportation as a pilot site for ICM because it's highly congested -- the fifth most congested city in the U.S. -- and it's getting worse. U.S. 75 also represents the perfect place to test the concept, given the range of transportation assets along the corridor: a freeway with frontage roads, managed HOV lanes, a tollway, 167 miles of arterials, bus routes, a light rail line and 900 traffic signals. The highway itself carries about 250,000 vehicles every weekday.
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"All the agencies were really facing a situation where, alone, we'd pretty much done everything we could to make things better," says Robert Saylor, transportation engineering and operations manager with the city of Richardson, a Dallas suburb. "The only way to improve beyond what we're doing would be to do some coordinated actions."
ICM works by collecting data about traffic conditions, then sending it through software that can analyze the data and help operators select the best strategies for managing it. A Web interface ensures all the relevant agencies working on the corridor are aware of what's happening. Once officials decide how to respond, that information is pushed out to commuters via a new website, 511dfw.com. Electronic signage will also direct drivers to alternate routes. For example, if there's a collision on U.S. 75, traffic can be redirected onto the frontage road and back onto the freeway via electronic signage, thus bypassing the collision. The idea is that if traffic on the frontage road is light, officials can take advantage of the capacity that's largely being unused.
Because traffic engineers would have planned for many different scenarios ahead of time, they'll know exactly how to tweak the timing of the traffic lights on the frontage road or even arterial roads to accommodate the overflow. In the past, when there's been a morning rush hour collision, officials might not have changed signal timing, or if they did, the changes might not have extended beyond a given city's boundaries. Now, "as soon as we got notification the incident happened, we'd go in with just a couple clicks and re-time the signals," Saylor says.
The focus of the program is more on coordination than technology, since things like loop detectors and speed monitors are largely already in place. A pre-programmed pattern, for instance, would ensure Richardson's lights are coordinated with those of neighboring cities like Dallas and Plano, and the pattern would be designed to maximize efficiency of exiting freeway traffic while balancing the needs of other drivers.
If there's an extremely disruptive situation, freeway drivers could be directed to exit and take the light-rail to work. Because the number of available parking spaces at park-and-ride facilities are monitored, as is existing light-rail ridership, drivers would only be directed to the facilities where there's room to accommodate them.
The project is funded with $5.3 million from the U.S. Department of Transportation, a local share of $3 million and nearly $1 million in other federal funds. Officials say the benefits from things like travel-time savings and reductions in fuel consumption and emissions, amount to about $264 million in savings over 10 years. San Diego is also in the midst of a similar ICM study.
After a year, the pilot will be analyzed. If the results are promising, ICM could prove to be an inexpensive but effective tool for managing traffic conditions at a time when transportation agencies are short on funding. "There's a lot of interest in implementing this," Olyai says. "It's logical. It's low-cost. It's using existing assets more efficiently."
