Knowledge Resources

The Washington State Department of Transportation (WSDOT) implemented High Occupancy Tolling on a nine mile section of SR-167 between Auburn and Renton, Washington. The facility included a single High Occupancy Toll (HOT) lane and two general-purpose lanes in each direction. The general purpose lanes were toll free and open to all traffic. The HOT lanes were also toll free for car-poolers, transit, and motorcycles, but solo drivers were required to pay an electronic variable toll to use the facility. When capacity was available, solo drivers equipped with an in-vehicle transponder tag could use the facility to avoid congestion for high priority trips.

Detailed performance data were collected after the facility opened in May 2008. Annual evaluation reports were provided to the State legislature and Transportation Commission.

FINDINGS

Performance analysis measured average peak period traffic conditions from May to November 2009, and the findings were compared to the same period in 2007. The following results were reported. (Note: Results from 2008 were omitted due to conflicting construction projects.)

General Purpose Lane (Speed and Volume)

• Average speeds increased by 21 percent (from 40 mi/hr to 49 mi/hr).
• Average traffic volume increased by 11 percent.

HOT Lanes (Speed and Volume)

• Average speeds increased by 6 percent (from 57 mi/hr to 61 mi/hr).
• Average traffic volume increased by 4 percent northbound and 1 percent southbound.

Notwithstanding the influence of construction activities and gas price spikes in 2008, the overall average number of tolled trips increased by 46 percent, from 1,230 trips per weekday in May-November 2008, to 1,795 trips during the same period in 2009. During peak hours, the average number of northbound daily tolled trips increased from approximately 170 trips in 2008 to 280 trips in 2009 and the average number of number of southbound trips increased from approximately 120 trips in 2008 to 160 trips in 2009.

Bus ridership in the corridor increased greatly from 2007 to 2008 as gas prices peaked in the summer of 2008. Fewer rode the bus in 2009 following the reduction in gas prices, economic instability, and regional job loss. The trend was consistent throughout south King County and Pierce County.