Thursday, October 10, 2019

The nuts and bolts of installing a big temporary bridge

By Tina Werner

Many of us know the fun and wonder that comes from building with LEGOs and other blocks. Seeing objects come together right before our eyes is amazing. People in Buckley in east Pierce County are about to see something equally impressive get built in their community, only this won't involve red, yellow and green plastic bricks.
A bulldozer pushes the first section of the temporary bridge across Spiketon Creek.

The State Route 162 Spiketon Creek Bridge has been closed since Aug. 2018 due to almost 4 inches of pier settlement. Like constructing a LEGO Star Wars battleship, work to rebuild the bridge has been happening in stages, piece-by-piece.

Now it's time to install a modular bridge across the creek overlooking Foothills Trail, but this isn't just any modular bridge. The temporary structure will be one of the largest single-span, multi-lane temporary bridges ever produced, approximately 240 feet long and 32 feet wide. Acrow Bridge, which specializes in prefabricated modular steel bridges, produced the structure.
When complete, the temporary bridge across Spiketon Creek will be 240 feet long and weigh 320 tons.

If the schedule holds, contractor Hamilton Construction Company of Olympia hopes to be ready to reopen this section of SR 162 by late November. Once the temporary bridge is open, it will accommodate a single lane in each direction with no load restrictions.

How'd we get here?

While preparing for a month-long deck repair of the Spiketon Creek Bridge, we discovered significant pier settlement so for safety, we closed the structure on Aug. 16, 2018. The closure has meant a detour for the 5,600 drivers who use the bridge daily.
The temporary Spiketon Creek bridge has 352 individual truss panels that will be bolted and pinned – this is one of the pins – together. The pins connect the individual truss sections transversely and 5,320 bolts connect it longitudinally.

After extensive meetings with the community and elected officials, the decision was made to stick to the original plan of replacing the bridge in 2026 and using a temporary span until then.

What has been going on?

Crews have been working six days a week to meet our target deadline of late November to open the bridge to vehicle traffic. The contractor is assembling the temporary bridge on the east end and rolling, or “launching” it across the creek. This work is taking place in three stages. The first launch happened on Wednesday, Oct. 2 when crews pushed the first section of the bridge forward to make room to build and connect the next section. It is quite a detailed process but again, think of assembling LEGOs and building it piece by piece. There are exact parts that are required to be installed at just the right time to successfully span the creek. Because the bridge is already closed at the site, and for public safety, we are not able to accommodate public viewings for the remaining two launches.
One of the 5,320 bolts that will connect the bridge components of the temporary SR 162 Spiketon Creek Bridge.


The remaining two bridge launches are scheduled to occur over the next two weeks. Check our project webpage for updates, including more photos of the progress.
All of the components of the temporary Spiketon
Creek Bridge, including the aggregate anti-skid
epoxy coated deck panels, were made in the
United States, mostly from recycled steel.

A happy Thanksgiving?

The contractor anticipates completing the work by late November and reopening the structure before the Thanksgiving holiday. Once the bridge is open, the signed detour will be removed and no further closures of the Foothills Trail – which is owned and operated by Pierce County – will be required.

We appreciate the public's interest and patience throughout the entire process. We are also eager to eliminate the lengthy detour and reopen the vital crossing for east Pierce County travelers.