Crunching Numbers and the Bellevue Bridge

by guest blogger Steve Peer

As part of the I-405 Bellevue Braids Project crews are removing the old NE 12th Street Bridge to replace it with a new bridge.  The new bridge will be longer and wider and accommodate new ramps traveling to SR 520 and I-405. 

A Construction worker pulls out wood
from the inside of the NE 12th Street bridge. 
The wood was originally used to form
the old structure and hasn’t seen the
light of day since 1970.  We’re recycling
100% of the bridge, so we’re separating materials:
  wood, rebar and concrete are all being recycled locally. 
Crews will use heavy equipment to crunch the old NE 12th Street Bridge down and the countdown begins.  On April 1 we’ll close all lanes of I-405 through downtown Bellevue to safely remove the bridge that’s spanned I-405 since 1970.

Here are some numbers for you to crunch:

300, 54, 14
  • Located just south of I-405/SR 520 interchange the old NE 12th Street Bridge runs about 300 feet long and 54 feet wide and is just 14 feet above I-405.
384, 96, 16 
  • The new bridge will be 384 feet long, 96 feet wide and 16 1/2 feet above I-405.  The wider bridge will have a bicycle and pedestrian lane separated from traffic. 
2 Statues of Liberty
  • The total weight of debris being moved from the old bridge is equivalent to the weight of 2 Statue of Liberties. 
21 Boeing 747s
  • Nearly 8 million pounds (4000 tons) of concrete will be crunched into smaller chunks and hauled away—about the weight of 21 Boeing 747s.
1 blue whale
  • 450,000 pounds (225 tons) of rebar will be extracted. This is equivalent to the weight of an adult blue whale.
675 tons of sand
  • 1.3 million pounds (675 tons) of sand will be placed on the roadway - acting as a buffer to protect the roadway from falling debris from the bridge. 
  • Crews will use about 20 pieces of equipment to remove the old bridge including:
  • 2 huge excavators with special attachments (crunchers)
  • 2 smaller machines with breakers or “bucket”
  • 2 loaders
  • 8 Big (30 ton capacity) trucks will continuously remove debris and recycle it locally

The final number may be the most important.

53 hours
No Fooling - beginning Friday, April 1 at 11pm we’ll close I-405 completely  in both directions for 53 hours. 

You won’t be able travel I-405 through downtown Bellevue for the remainder of the weekend until Monday at 4 am, but there are detours in place.