You won't hear Casey Kasem counting down these “Top 40s.”

In the first study of its kind, the Texas Transportation Institute calculated traffic flow in 328 U.S. travel corridors over a variety of times — all day, morning and evening peaks, midday, and weekends — to identify the most congested areas. While accounting for only 6% of total lane-miles and 10% of traffic, these corridors account for 36% of urban freeway congestion.

Seven of the top 10 overall congestion leaders are in and around Los Angeles:

    1. Los Angeles Harbor Freeway/CA-110 from I-10/Santa Monica Freeway to Stadium Way/Exit 24C
    2. Los Angeles Harbor Freeway/I-110 from 111th Place to I-110/I-10/Santa Monica Freeway
    3. Los Angeles San Diego Freeway/I-405 from I-105/Imperial Highway to Getty Center Drive
    4. New York Van Wyck Expressway/I-678 from Belt Parkway/Exit 1 to Main Street/Exit 8
    5. Los Angeles San Gabriel River Freeway/I-605 from Beverly Boulevard to Florence Avenue
    6. Los Angeles Santa Monica Freeway/I-10 from CA-1/Lincoln Boulevard/Exit 1B to Alameda Street
    7. Los Angeles Santa Monica Freeway/I-10 from I-5/Golden State Freeway to National Boulevard
    8. San Francisco I-80 from (James Lick Freeway/Bay Bridge) US-101 to Treasure Island Road
    9. San Francisco Grove Shafter Freeway/CA-24 from Saint Stephens Drive to the Caldecott Tunnel
    10. Los Angeles I-110 from West Vernon Avenue to 51st Street

The report suggests a combination of solutions that DOTs and traffic engineers already know about, including new or expanded transit facilities, aggressive crash removal; improving commuter information; and creating bike-friendly, walkable communities. Employers are encouraged to offer telecommuting and flexible work hours to help relieve bottlenecks. Download 2011 Congested Corridors Report at http://go.hw.net/pwcorridors.