All those conditions contribute to congestion and hinder mobility. But they don’t resonate equally with a traveler in Bowie and another in Centreville, let alone with one in Boston or New York.
This creates a difficult task for the researchers trying to quantify the experience of congestion and for the travelers trying to understand what they are experiencing.
The Urban Mobility Report by the Texas Transportation Institute is the study that has become the benchmark for badness. It tries to quantify the problem in several ways. No one measure satisfies all travelers, but the collective impact is telling.
You will see that the D.C. region does very badly overall, even if we’re not always worst in the nation.
Also note that our congestion isn’t worsening as quickly as in the late-20th century, and consider the effect on our transportation planning.
Indexes and measurements
We’re counted among 15 Very Large Urban Areas in the most recent report, which measured mobility and congestion in nearly 500 urban areas based on 2011 data.
Within the large-area group, the worst performers are the D.C. region, Los Angeles, San Francisco, New York and Boston.
Nationwide, many types of congestion recorded in the study peaked around 2005. The report suggests that this is a short-term achievement. The conditions that fuel congestion will return as the economy improves, the report says, and congestion solutions are not being pursued aggressively enough.
Annual Delay Per Auto Commuter: This measures all the delays for commuters who drive in the peak period (6 to 10 a.m. and 3 to 7 p.m.). The institute says it illustrates the effect of congestion per mile as well as the length of each trip.
In 1982, the yearly delay nationwide was measured at 16 hours. It was 39 in 2000 and 43 in 2005 but shrank to 38 by 2010 and has remained there.
The D.C. region ranks first, with 67 hours of delay per year. Los Angeles and San Francisco were tied for second, with 61 hours. The national average among the 15 Very Large Urban Areas studied was 52 hours. Baltimore, considered a Large Urban Area, ranked 23rd, with 41 hours.
Travel Time Index: This measure is a ratio comparing travel time at rush hour with uncongested travel time. An index of 1.30 would indicate that a trip taking 20 minutes when traffic flows freely would take 26 minutes during the peak. The national index had reached 1.23 in 2005 but declined to 1.18 in 2010 and 2011.
The D.C. region ranked fourth in the 2011 data, with an index of 1.32. The Los Angeles region was No. 1, with an index of 1.37. Almost all of our rise on this often-cited index occurred between 1982 and 2000.