Congestion Management Monitoring
Report Summary
1999

Corridor Congestion

During afternoon rush hour there is significant congestion along major facilities such as I-5, I-205, SR-14, SR-500/Fourth Plain, 164th Avenue, and Ward Road. In the PM period, additional congestion is shown along Mill Plain-East, Burton/18th Street, SR-503-South, and SR-502. Planned improvements along Ward Road, Burton, and SR-502 are likely to reduce the congestion index in these corridors.

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Speed as Percent of Speed Limit

I-5, I-205, and SR-14 operate at 80% or more of the posted speed in the afternoon rush hours. The SR-500 corridor, from Andresen Road to SR-503, operates at less than 65% of the posted speed. Unlike the other freeway facilities, SR-500 has several at grade intersections, which affects the average travel speed in the corridor. In general, arterial facilities, with at-grade intersections, display lower percentages. The eastern portions of Mill Plain and SR-500 display the lowest percentages of all the CMS corridors during the PM peak period at less than 50% of the posted speed.

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Transit Seat Capacity Used

Transit seat capacity is based on 1999 C-TRAN bus service and represents the percentage of seats that are occupied by passengers during the two hour peak period. During the AM, I-5 from 134th south to the Interstate Bridge, transit passengers utilize more the 45% of the available seats. In addition, Fourth Plain west of Andresen Road uses the highest amount of available capacity of the corridors that do not have express commuter bus service. Significant portions of the transit system are at more than 30% of capacity over the 2 hour AM period.

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This report was prepared by: