I-90 Floating Bridge

The I-​90 Floating Bridge straddles both the cities of Seattle and Mercer Island. I’m sure the boundary is somewhere in Lake Washington, just as the boundary between San Francisco and Oakland is somewhere along the Bay Bridge in the middle of San Francisco Bay. However, for convenience’s sake, I’ve added the zip code for the Mount Baker/​Beacon Hill neighborhood in Seattle, where I-​90 «disappears» into the Mount Baker Tunnel.
There is no doubt that this a 5 star event. A visitor to Seattle really needs to veer east of Pike Place Market, the waterfront, downtown, Belltown, Seattle Center, and Queen Anne Hill to see this engineering marvel. Even if you drive over it every day, it never fails to impress.
It’s best to think of the I-​90 Floating Bridge as a system and there was no listing for the engineering and architectonic aspects of this major project. It’s not just a floating bridge. It is more than that. First, with the upgrade of 1990, there are now two bridges. The westbound traffic and the reversing express lanes travel on the Homer Hadley Bridge. The eastbound traffic travels on the Lacey Murrow Bridge. A wide path which accommodates pedestrians and cyclists is at its northern edge, offering a view of the other floating bridge on Lake Washington, that being the Evergreen Point Floating Bridge, or simply the 520 bridge. When light rail will connect Seattle to the Eastside suburbs, it is planned to cross on I-​90 and not on the 520 bridge.
This was one expensive stretch of interstate. In addition to floating concrete pontoons, both sides of the floating bridge, be it in Seattle or on Mercer Island, have some impressive structures, amenities, details, and landscaping.
The procession is much more fascinating going from east to west, as would be the case in going from Oakland to San Francisco. One descends from Bellevue onto Mercer Island on the East Channel Bridge and gets a peekaboo view of the lake and parts of Seattle in the distance. Once on Mercer Island, the detailing on the concrete retaining walls is simple but really nicely done, as are the evergreen studded medians. Before leaving Mercer Island, one enters the Mercer Island Lid, which is a cover for the freeway and construction above it. It is even more interesting because it curves. Upon exiting the Mercer Island Lid comes the icing on the cake: crossing Lake Washington on the 1.5 mile pontoon bridge. As Seattle comes into view, so does the Mount Baker Tunnel, which is deep beneath the hill that contains this lakeside neighborhood of the same name. Within the Mount Baker Tunnel, traffic appears to be divided into different «chutes,» depending on the time of day. Upon exiting the tunnel, Seattle’s downtown skyline comes into view and the junction with I-​5 is at hand.
Whew. That is some sensory overload. For a while, this was reputedly the most expensive stretch of interstate, in terms of cost per distance, in the U.S. Then, it was reportedly eclipsed by Boston’s «Big Dig,» or the placement of a lid over the Central Artery as it wound around the CBD of Boston. Boston definitely benefited from it and there are green spaces above that project as well. However, the Boston project was under the spotlight more because of its huge budget overruns and other controversies and mishaps. Not only that, going right through a downtown area had to have been more complicated.
Keep in mind that, while different projects, they have something in common. These projects are found at roughly both ends of I-​90, being that I-​90 crosses the U.S. from Seattle to Boston, though the «Big Dig» or Central Artery is technically on north-​south I-​93. Visit both if you can.
However, if in Seattle, this is a must see attraction which you can just drive across. Better yet, if it’s a sunny or temperate day, you should walk, run, or bike across the flanks of this incredible stretch of roadway!