National top highway chokepoints study

   A new report by the Texas Transportation Institute identifies 328 stretches of highway across the nation that are seriously congested on a regular basis over a variety of times during the week.
   The least reliable corridor is the southbound section of Georgia Route 400 in Atlanta between the toll plaza and I-85. According to the study, drivers have to allow 256 percent more time than the average to complete their trip on time 19 out of 20 times.
   The northbound Van Wyck Expressway in New York between Belt Parkway and Main Street ranked highest in the study’s planning time index, meaning a driver has to add 588 percent more time to ensure on-time arrival for 95 percent of the trips. It takes 272 percent longer to make a trip on this stretch of road during [choke] periods than when traffic is freely flowing.
   The New York area has five of the top 20 corridors for least reliable travel. Atlanta and Washington, D.C., each have two corridors in the top 20.
   The highest ranked corridor for delay per mile is the Harbor Freeway (northbound) in Los Angeles from I-10 to Stadium Way, with about 1.4 million hours of delay per mile. Although it ranks first in delay per mile, it
ranks 27th in total congestion cost because it is one of the shorter corridors in the study.
  Other results from the study include:

    • 7 of the 10 most congested corridors in the United States are found in the Los Angeles region;
    • The top 21 corridors in this list had at least a half million hours of delay per mile in 2010;
    • 284 corridors contained at least 100,000 hours of delay per mile in 2010;
    • The most wasted fuel and highest congestion cost occurred on US 101 southbound in Los Angeles between Ventura Boulevard and Vignes Street, which is a 27-mile stretch of roadway.

   The study of travel time reliability could help transportation planners prioritize where to direct limited transportation funds. Many transportation experts have recommended that a portion of federal aid to states be targeted to corridors that have importance beyond local commuting because they are used to move people and freight across regions or the nation. Expanding capacity or making other improvements to traffic flow on relatively few chokepoints can have a disproportionate impact on the broader road network, they say.
   The Texas Transportation Institute, part of Texas A&M University, publishes an annual report ranking congestion levels in U.S. cities and showing how much time and economic productivity is wasted each year by traffic congestion. The Congested Corridors Report, conducted in conjunction with traffic data analytics firm INIX, is the first attempt to go beyond measuring average congestion levels and specifically identify chokepoints and the day-to-day variation in congestion in major urban areas.
   The study said that the 328 corridors account for 36 percent of the nation’s urban freeway congestion, but only 6 percent of the total freeway lane-miles and 10 percent of the traffic volume. The corridors account for eight percent of the national and 33 percent of the urban truck traffic that experiences delays.
   It found that travel time reliability is more of a problem around bridges, tunnels and toll facilities because there are few alternate routes and because a small incident can have a big effect on corridor travel times. When travel time variability increases, trips become less predictable.
   Among the possible solutions for smoothing out traffic flows, the TTI said, are:

    • Adding road capacity, new or expanded transit facilities, larger rail and bus fleets;
    • Traffic management strategies such as aggressive crash removal;
    • Demand management strategies like improving commuter information, employer-based ideas such as telecommuting and flexible work hours, and congestion-based tolling; 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.

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