I-90 survey responders report heavy use

WSDOT’s recently released I-90 traffic study, shared alongside scoping feedback last week, reinforces what’s already well understood—that 98 percent of those surveyed make trips across the water over the course of a week, and that for a range of reasons—economic, social and traffic-related—Islanders widely oppose tolling.

In November, the state agency mailed surveys to all 10,073 Island households as well as businesses, asking them to track the number and reasons for their travel. But the above numbers, high as they may be, only account for the 3,595 Island households that returned a survey in time (a response rate of 38 percent).

“The WSDOT survey and scoping report reflect what we have been aware of for a long time—tolling would have significant adverse impacts on the region,” said city manager Noel Treat in an email.

Around the same time, WSDOT also collected feedback in the form of public hearings, online forums and written word.

A quick glimpse at the numbers reveals that most trips were made during peak commute hours and that more total residential trips are made between Mercer Island and Bellevue — 54 percent— than to Seattle; and that weekly work-commute round-trips range from a single commute, to as many as 90. Islanders average in both directions of the bridge, seven round-trips per week.

The survey was also distributed among Island businesses, which showcased similar trends but smaller volumes. More Island businesses reported work-commute trips between Mercer Island and Bellevue (55 percent) than to Seattle.

Results also revealed a glimpse into Island lifestyles. Almost half (48 percent) of Island households own at least two cars, and 32 percent have three or more.

“While we knew Mercer Island’s ramp volume, what we didn’t know, was for what purposes [people were traveling] and how that broke down,” said John White, WSDOT’s Director of Tolled Corridor Development.

Islanders have argued that tolling of I-90 would grossly impact the city’s employees, many of whom don’t live on the Island. Sixty-one percent of households responding reported service workers—such as housekeepers, nannies and yard care employees—as using the bridge, for an average of five one-way trips over the course of the week.

“This more detailed breakdown of things gives us confidence in the EIS and when looking at alternatives,” said White. “Our analysis will reinforce how different approaches to tolling would affect areas of focus—how it would affect commuters and businesses.”

The themes identified in scoping feedback were also what you might expect, ranging from concerns about how tolling would impact home values, to what it would mean for the greater Puget Sound region.

The next step, says White, is to implement and deliver a draft EIS. The above results will help WSDOT identify the range of alternatives to be studied. Transportation leaders will also be watching the Legislature and anticipate more nuanced discussions about the future of transportation state-wide.

Last year, the city announced in late 2013 that it was searching for a transportation expert to review the traffic portion of an EIS.


For the complete survey results and scoping summary reports, visit:


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