TomTom today revealed the first fully detailed view of which cities have the worst traffic in the United States. The results were calculated using data from Speed Profiles, the historical speed database from TomTom map business unit Tele Atlas that helps personal and professional fleet drivers using portable, in car or smartphone navigation systems avoid trouble spots and save time and money.
Speed Profiles aggregates the actual speeds that millions of anonymous, GPS-enabled drivers have traveled over the last two years. This community of drivers is the largest GPS data collection community in the world. It provides actual average speeds for every five minutes of the day on roads across the full network to help show a far more accurate view of historic traffic. In contrast, traditional historical traffic systems use random sampling from a limited number of road sensors on primary roads or from fleet vehicle traces.
Cities were ranked as most to least congested according to how fast cars could travel on the street network. A city’s traffic was defined as congested if drivers could travel at only 70% or less of the posted speed limit, meaning on average an hour long commute included 20 minutes or more of significant delays.
The results of the continental U.S. states reveal some interesting surprises:
- Seattle, Washington is the city with the worst traffic in the United States, with an average of 43% of its roads showing heavy delays. Rounding out the top five cities after Seattle are Los Angeles (38%), Chicago (37%), San Francisco (35%) and New York (31%).
- The “Bay Area” of California has the most cities in the top 30, with San Francisco, San Jose (29%) and Oakland (28%).
- The most congested “corridor” is between Baltimore and Washington, D.C. About 36% of that area’s roads, largely in Montgomery County, are congested.
- While New York has many pockets of heavy congestion, the area also contains many major arteries for alternative routes. In fact, cities with fewer options for alternative roads were higher on the list.
- The least congested of the top 30? Minneapolis, Minnesota. Only 17% of the roads in that city are congested.
When all U.S. states and territories are included, the Toa Baja and Bayamón areas of San Juan, Puerto Rico are both in the top ten. Approximately 24% of the streets in greater San Juan are congested.
