In December 2006 and January 2007, crews set the girders for the new pedestrian bridge over I-405 at the SR 527 interchange. Below are some facts about this major milestone for the project.
By the numbers:
- Number of girders: Six
- Length of longest girder: 124 feet - approximately 8 car lengths
(this is the girder that spans all southbound I-405 lanes)
- Length of shortest girder: 70 feet - approximately 4 car lengths
- Height of each girder: 5 feet
- Width of each girder: 6 feet
- Weight of heaviest girder: 162,205 lbs (81 tons) - about as much as 40 cars
- Weight of lightest girder: 92,056 lbs (46 tons) - about as much as 23 cars
- Cost of each girder: Ranges from $56,000 to $99,000
- Total cost of all six girders: $472,800
Other facts:
- We used trapezoidal tub girders, which are pre-cast concrete girders shaped like a bathtub.
- The girders were fabricated at Central Pre-mix Prestress in Spokane.
- The cold winter weather in Spokane created a challenge for the girder manufacturer. The concrete had to be at least 50 degrees while it was curing. This meant it had to be at least 10 degrees above zero in Spokane. Otherwise, the manufacturer's equipment could not keep the concrete warm enough for it to set properly.
- Delivery of the girders from Spokane to Bothell depended on road conditions at Snoqualmie Pass.
- We set the four girders over and adjacent to southbound I-405 in December. We set the two girders over northbound I-405 in January.