January 7, 2012

Reliably Unreliable

The Congestion Problem: TTI identifies the worst stretches of highway that offer unpredictable travel times.

In the first nationwide effort to identify specific stretches of highway responsible for significant traffic congestion at different times and on 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.

The 328 corridors studied in the Texas Transportation Institute’s 2011 Congested Corridors Report represent just 6 per­cent of the nation’s lane miles, but account for 36 percent of the country’s urban congestion.

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 3 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.

The report describes congestion problems in 328 seriously congested corridors over a variety of times — all day, morning and evening peaks, midday, and weekends. 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.

“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.”

How 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.”

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 of the following congestion solutions:

• 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. “If we can place our schools and places of work closer together, we can minimize trips,” he said. “In some places it makes sense, but it in other places, it may not be an option. But when you’re thinking about buying a 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



At a Glance

The Key Findings of the Texas Transportation Institute Study

• The 328 corridors, while accounting for only 6 percent of the nation’s total freeway lane-miles and 10 percent of the traffic, account for 36 percent of the country’s urban freeway congestion;

• The 328 corridors account for 8 percent of the national truck traffic and 33 percent of urban freeway truck delay;

• Travel time reliability is more of a problem around bridges, tunnels, and toll facilities, both because there are few alternate routes available in such circumstances and because a small incident can have a huge effect on corridor travel times;

• When travel time variability increases, your trip becomes less predictable. Every occurrence of an unpredicted travel disruption creates slower speeds than normal and contributes to an increase in reliability measures.


The Highway Trust Fund:

The bleeding is temporarily stopped but it continues its fight for life

The bumpy road the construction transportation industry has endured for the Highway Trust Fund (HTF) may have taken a slight step forward. On Nov. 18, President Obama signed a bundle of appropriation bills for fiscal year 2012 into law — including $39.14 billion in obligation limitation for the highway program — a decrease of nearly $2 billion from this fiscal year. An additional $1.66 billion was also appropriated for highway-related “emergency relief.”

However, the solvency of the HTF is still in jeopardy, according to construction transportation expert Ken Orski, who writes and publishes Innovation NewsBriefs (

He says that Congressional conferees have warned that the bill will deplete almost all resources from the HTF by the end of fiscal year 2012. Without large amounts of additional revenues this year, the HTF is not expected to be able to support a highway program in fiscal year 2013.

The appropriations measure was passed in the House 298 to 121 and in the Senate with a 70-to-30 vote. Although the transit program is funded at about $10.31 billion — a $400 million increase from fiscal year 2011 — the Transportation Investment Generating Economic Recovery program has been kept at $500 million, which is a slight decrease from fiscal year 2011, according to Innovation NewsBriefs. No funding was provided for high-speed rail and the InterCity Passenger Rail Service program. The Livable Communities Initiative and the National Infrastructure Bank also were not allocated any funding for fiscal year 2012, according to the NewsBriefs report.

House Transportation and Infrastructure Committee Chairman John L. Mica (R-Fla.), Speaker of the House John Boehner (R-Ohio), and other House Republicans have made plans to proceed with a long-term transportation reauthorization bill. In a press statement, Mica called Boehner’s action to move ahead “a milestone and a great step forward” in building the nation’s infrastructure. Mica refers to it as a “key component” of the Republican jobs proposal that will get Americans working while providing then with “a long-term and fiscally responsible plan.”

At Aggregates Manager press time, Mica announced that the Transportation Committee would not act on the bill in December as previously anticipated. According to a report in Transportation Issues Daily, the earliest the House is expected to take action is the week of Jan. 16, but a February debate appeared more likely.

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