Bothell plans replacement of North Creek bridge
February 16, 2011 · 11:30 AM
Bothell officials have revealed plans to replace the 240th Street Southeast bridge over North Creek.
The bridge has been closed to all traffic since October when the city announced an inspection had revealed significant deterioration of at least one bridge support.
Initially, the city just closed the bridge to eastbound traffic. But the decision shortly was made to shut down the span completely.
According to Bothell Project Engineer Khin Gyi, a new bridge likely won't be in place until the end of 2012. The city plans to release bids for the roughly $3.5 million project in the fall of this year. But Gyi added North Creek is a salmon-bearing stream.
With that in mind, construction work can't be done during salmon runs or spawning seasons. The city can't complete any work on the bridge between roughly July and September and it's that factor that pushes construction forward into next year.
Bothell is using federal funds to pay for the work, which also means plans must pass through a more stringent environmental review than they might otherwise. Gyi said there is a slight, but very slight, chance Bothell might be able to obtain permits sooner than current projections. If that happens, construction could be moved up and the bridge replaced by the end of this year.
Again, Gyi emphasized several times that obtaining permits early is a long shot.
"It's a very slim chance," she said, describing even the scenario in which traffic is crossing the bridge by the end of 2012 as "optimistic."
Bothell Traffic Manager Seyed Safavian said the city does not know exactly how many drivers used the bridge. He said no count of cars specifically for the bridge ever was completed. But Safavian added 5,000 to 6,000 cars use nearby Fitzgerald Road daily. He assumes the amount of traffic reaching the bridge is similar.
Safavian added the city did a lot of traffic counts and studies in the area around the bridge following its closure. Officials wanted to determine what streets were impacted by the closure. Safavian said the worst hit roadway was 228th Street Southeast, which sits north of the bridge. The city adjusted lights at three intersections to accommodate the new, if presumably temporary, traffic pattern. Safavian said officials even tried placing a police officer in the area to address traffic congestion problems.
Gyi said the design of the new bridge calls for a 70-foot-long "channel" bridge carrying a 30-foot wide roadway. That roadway will consist of two 11-foot-wide lanes of traffic and two four-foot shoulders. Built in 1962 in line with 1962 specifications and codes, the existing bridge does not include shoulders and is considerably shorter at only 30 feet in length.
According to Gyi, the longer length accommodates more water moving through North Creek. She said the new bridge will be high enough to stay above even a 100-year flooding event.
"It lets the water spread out a lot more," Gyi added.
The longer bridge does mean the city's plans will impact an adjacent pedestrian bridge over North Creek, a bridge that is part of the North Creek Trail. That bridge has not been closed. Originally, Bothell did not intend to replace that span, but Gyi said the length added to the vehicle bridge necessitates replacing the walking bridge. The second bridge will be replaced with a prefabricated unit.