It has been two weeks since the tolling on SR-520 has taken effect and SDOT engineers are still monitoring traffic very closely. Initially, traffic on SR-520 decreased by 40% while I-90 and SR-522 increased by 11% and 10% respectively. The expectation is that traffic patterns will change day to day throughout the region while drivers make adjustments in their travel, such as trying different times and routes, riding the bus, taking a vanpool or carpool, etc. This adjustment period, as noted by WSDOT, can last for up to six months as drivers settle into new traffic patterns. After this period, it is expected that there will be just a slight increase of traffic on I-90 and SR-522 during rush hours as compared to volumes before the tolling.
Screen shot of traffic camera at Lake City Way NE e/o 15th Ave NE
The initial effects of the SR-520 tolling have been reduced congestion on Montlake Blvd and only a slight increase in volume along Lake City Way that has not warranted an adjustment to signal timing.
You can find information about SR 520 toll rates online at: http://www.wsdot.wa.gov/tolling/tollrates.htm