 A modern bridge for modern times
Narrator Says: King County’s new Tolt Bridge uses the latest bridge-building technology to create a span over the Snoqualmie River that can stand up to the demands of modern life, and yet honors the natural beauty and history of the Carnation area. It replaces the existing Tolt Bridge, which was constructed in 1922. The old bridge was dedicated on October 21st of that year. Approaching its 86th birthday, the bridge has had a useful life, despite the fact that it can no longer handle modern truck loads, as well as traffic and pedestrian needs. The earliest non-native settlers began arriving in the Tolt area, now known as the town of Carnation, in 1858. For several decades the lack of a span over the Snoqualmie River limited access to the west, most notably Seattle, for entrepreneurs looking to move such goods as coal, timber, and agricultural products. These economic factors, and the large loads were what led county engineers to recommend the original timber bridge be replaced with a steel structure. 85-and-a-half years after its birth, the roughly 700-foot span including its approaches, has been replaced by the new span, roughly 1000 feet long, that features a lot more breathing room for cars, cyclists and pedestrians. King County Inspection Engineer Wes Chin Says: We're standing on 9-foot lanes here, in our new bridge we've widened it out to 12-foot lanes, with additional 8-foot of shoulder space, which allows for pedestrian traffic as well as bike traffic so that improvement alone is going to improve traffic flow through here and just take out some of the traffic problems that this old bridge had created and we also realigned the roadway so that it's up to standards in terms of speed and modern-day traffic. This bridge was built in 1922, 86-year-old structure, the steel's been covered with lead paint for years and our new design we've added a second span, we're looking at about 1.7 million pounds of steel in the two truss members and over 1,000 yards of concrete for the decking alone. Narrator Says: The new Tolt bridge has what’s called an HL-93 rating by engineers, meaning it is built solid and can handle more than 50 tons of weight. The $28 million structure resides just 165 feet upstream from the old bridge. One challenge for county engineers was how to minimize impacts to the Snoqualmie River and its sensitive surroundings as much as possible. Two new long trusses were constructed to span the river and its surroundings. King County Environmental Engineer Katherine Merrell Says: One of the things we looked at when we were redesigning the bridge was trying to avoid the large wetland complex on the west side of the river and we decided that we would need to put the supports outside of it. It was a really long span and a difficult construct, but we were able to make it happen. We have a huge project team working on this bridge replacement. The other thing that we considered was having an extremely large span over the Snoqualmie River so that we did not have piers in the river channel restricting its movement. And as you can see today we've got some water on all sides of the piers on the existing bridge. So we've got a large river complex, the Snoqualmie river, we've got large wetland systems. We've got repairing areas to deal with, and we've got three tributaries within this project area that we also needed to take into consideration avoid impacts and mitigate wherever we create impacts. Narrator Says: During the two-year construction of the new Tolt Bridge, county engineers worked around many fish windows in order to further minimize impacts on fish habitat in the Snoqualmie River, and planted some trees and shrubs on the both sides of the river. The existing Tolt Bridge has been a state and county historical landmark for more than 10 years, and will be demolished and removed in the coming months, but county engineers have made sure this historical structure won’t be forgotten. King County Environmental Engineer Katherine Merrell Says: So we came up with a mitigation package that included providing a historic viewer at the bridge downstream from the project where you can look through the viewer and see an image of the old bridge superimposed while being able to see the new bridge in the background so you can remember what this old bridge looked like when it's gone which will be pretty soon. Narrator Says: The new Tolt Bridge opened on May 30th, with transportation modes from the past century on hand to commemorate the occasion. County leaders were also on hand to tout the new bridge’s modern features. King County DOT Director Harold Taniguchi Says: So as much as we love the old bridge for its historical look and long years of service, it just couldn't meet all of our transportation needs today and on into the future. This new bridge that we're standing on right now is wider, it includes shoulders on each side for walkers and bicyclists. It has a better alignment on both ends. It passes over instead of through sensitive wetlands and is built to withstand a major earthquake. The quality of the construction and design ensures that this is a bridge that will last as long as if not longer than the old bridge beside us.
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