Although it is not anticipated that the upcoming construction of State Route 520 will have significant direct impact on Madison Park, we will certainly have a front-row seat from which to view the expansion project when it gets underway in 2012. And it is almost certainly the case that the Arboretum will be directly affected by both the construction and the placement of one of the freeway on-ramps, depending on which design option is ultimately chosen.
Given the probable interest in all this by MPB readers, I thought I'd take a look at what the Washington State Department of Transportation (DOT) is saying about the SR-520 expansion and floating-bridge replacement program. Without much investigative effort I discovered that DOT has some pretty interesting information easily available on its site. The video above provides a visually arresting simulation of driving on one of three options for the "west side" approach to the new bridge (click on HQ in the lower right corner for higher-resolution video quality). Simulations of driving on the other two options are also available on the DOT website.
To date, the only construction that is underway on this project has to do with the testing of various methods for building the pontoons. This is happening in Satsop, with ultimate construction of the pontoons to take place in the Grays Harbor area. Some of the pontoons for the new bridge will be the largest ever built, according to the DOT: "360 feet long, 75 feet wide and weighing over 11,000 tons. That’s as long as a football field and as heavy as 23 Boeing 747 jets." That's big.
In case you wonder why the State thinks that the Evergreen Point Floating Bridge (pardon me, the Governor Albert D. Rosellini Bridge) is vulnerable and needs to be replaced, you need look no further than this simulation of the bridge's likely response to an earthquake: