Here's the single worst spot for traffic congestion, and the 10 worst U.S. cities

And the award for the nation's worst overall traffic hotspot goes to (drum roll) ... Interstate 95 in suburban Washington, D.C. But Los Angeles, predictably, is the nation's overall worst city for traffic congestion.

That's according to transportation analytics firm INRIX, which used its cloud-based Roadway Analytics tool to rank 108,000 traffic choke spots in the 25 most congested U.S. cities. It also calculated the economic costs in terms of projected wasted time, lost fuel and CO2 emissions over the next decade. Among the findings:

  • New York City had the most traffic hotspots of any city at 13,608.

  • Los Angeles notched the highest overall Impact Factor — defined by the duration, length and frequency of traffic snarls — on account of the severity and high number of hotspots (10,385). It pays the highest price at $91 billion in potential economic costs by 2026 if congestion conditions don't improve. L.A. claimed five of the top 10 traffic hotspots on the list and 10 of the top 25.

  • The worst single hotspot was southbound I-95 near Fredericksburg, Va., with nearly 1,400 traffic jams over the two-month study period stretching a whopping 6.47 miles and lasting on average 33 minutes. That one carried a potential $2.3 billion price tag by 2026.

  • The impact of L.A.'s hotspots and the potential costs to motorists was 42 percent higher than second-ranked New York, and three times higher than No. 3 Washington D.C. Atlanta and Dallas round out the top five, with Chicago, San Francisco, Houston, Miami and Boston filing out the ignominious top 10.

  • The cost of sitting in traffic jams in the nation's 25 most congested cities could reach $481 billion by 2026, or nearly $2.2 trillion over the next decade across the entire U.S.

INRIX says it also evaluated traffic-improvement efforts around its top 25 hotspots. It singled out Chicago, where a recent project to add a lane in each direction on the Jane Addams Memorial Tollway (I-90) helped increase westbound peak-hour travel speeds by 64 percent and led to other "smart" traffic improvements.

"Despite the local and state efforts to combat congestion at traffic hotspots, like the 'Congested Corridors' project in NYC or California's recent fuel tax increase, many challenges still remain to reduce congestion, including funding and financing at the federal level," INRIX's senior economist, Bob Pishue, writes in a related blog post. He noted the declining value of the federal gas tax, which hasn't been raised since 1993, and has been affected by the growth of more fuel-efficient combustion, electric and hybrid vehicles.

You can review the full findings here.

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