Reliably Unreliable Roads

The Congestion Problem: Texas Transportation Institute identifies the worst stretches of highway that you can count on to frustrate you by being unpredictable.

In the first nationwide effort to identify specific stretches of highway responsible for significant traffic congestion at different times and different days, the Texas Transportation Institute’s (TTI) 2011 Congested Corridors Report helps motorists ascertain exactly where to expect traffic delays and how to plan for them.

Researchers for the TTI (a Texas A&M University System agency) report noted that the corridors included in the report were identified by the data itself.

INRIX, a traffic data and analytics provider, originated the corridor approach, using 10 hours of congestion per week to define a starting point for a congested corridor. To be considered a “corridor,” according to the INRIX standard adopted for this report, congestion should impact a freeway segment at least three miles long.

“Until now, we’ve been able to measure average congestion levels, but congestion isn’t an ‘average’ problem,” TTI Research Engineer Bill Eisele noted in a written statement about the report. “Commuters and truckers are understandably frustrated when they can’t count on a predictable trip time from day to day.”

Eisele credited the data and corridor listing provided by INRIX with making it possible for researchers to quantify traffic congestion, and the even more frustrating variation in congestion from day to day in major urban areas across the country.

The report describes congestion problems in 328 seriously congested corridors over a variety of times – all day, morning and evening peaks, midday, and weekends. Much of our national congestion problem exists in a relatively small amount of our freeway system.

Not only were these roads found to have more stop-and-go traffic than others, they were also much less predictable — “so, not only does it take longer, commuters and truckers have a difficult time knowing how much longer it will take each time they make the same trip” said co-author David Schrank.

However, even more significant, Eisele told Aggregates Manager, is that the 328 corridors studied represent just 6 percent of the nation’s lane miles but account for 36 percent of the country’s urban congestion.

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“There are a relatively small amount of roads representing more than one-third of the congestion on roadways,” Eisele said in a phone interview. “This is striking. These are the places that are ripe for investment. There is probably a fair amount of benefit if cities and states can focus on these congested corridors.”

However, investment is made will vary depending on location. In some areas, Eisele pointed out, investment might mean additional lanes or additional transit such as rail or bus. In other areas it might mean aggressively clearing crashes off of a highway so additional congestion is not endured.

“It comes down to reassessing how and when we use the roadway system,” Eisele said. ”Do we all need to drive at the same time? Flex time and telecommuting could make some impact on congestion. This needs to be worked on with the business community.”

Although there is no single best way to fix the problem, the best solutions will come from efforts that have meaningful involvement from everyone concerned — agencies, businesses and travelers.

The study finds that the “best approach” is to consider all the congestion solutions are the following:

  • Traditional road building and new or expanded transit facilities;
  • Traffic management strategies such as aggressive crash removal;
  • Demand management strategies like improving commuter information and employer-based ideas such as telecommuting and flexible work hours; and
  • Denser development patterns with a mix of jobs, shops and homes so people can walk, bike or take transit to more and closer, destinations.

Eisele suggests that development patterns be considered for communities and cities. “Think about the trips you make on a daily basis — home, kids, work, medical,” he said. “If we can place our schools and places of work closer together, we can minimize trips.” Eisele does admit that in some cases, nothing may able to be done. “In some places it makes sense, but it in other places it may not be an option. There might not be much that can be done in some areas,” he noted. “But when you’re thinking about buying our home, look at how transportation plays a role. This is all part of the decision…and part of the solution.”

Adds study author Tim Lomax. “If cities and states make the right investments in our most congested highway corridors, the return on those investments will be substantial. “Not only will we see more reliable trips for travelers and trucks, but we can also expect to see greater productivity and more jobs.”

For the full report, go to