Motorists experienced reduced congestion levels across the US state of Washington during the past year, when compared with 2007, according to a report.

The Washington State Department of Transportation’s (WSDOT) 2010 Annual Congestion Report includes results of an in-depth analysis of travel times, delay and congestion duration for commutes in 52 central Puget Sound and two in Spokane.

Average peak commute travel times improved on 31 of 38 studied high-demand routes in central Puget Sound, while estimated economic costs for drivers and businesses due to delay declined by 21% compared with 2007.

The report attributed economic recession and the completion of major congestion-relief highway projects for fewer delays and shorter travel times on high-demand corridors.

WSDOT said it has completed $2.4bn worth of 70 mobility projects designed to alleviate congestion by September 2010, of which routes I-405, I-5, State Route 518, SR 18, SR 167 and I-205 offered measurable benefits to commuters.