Orange cones, cranes, and fences are a regular sight in Asheville these days. It’s not always clear what’s going up, coming down, or on the construction horizon, though, so we asked for your construction questions and got to investigating. One of the most frequently mentioned projects was the Blue Ridge Parkway bridge that’s going up over I-26 between exits 33 and 37 (it’s even got its own Facebook page), so we started there. And NCDOT had the answers.
The new bridge is part of the I-26 widening project. The existing bridge’s piers don’t allow for space to place the expanded eight full lanes, so the new bridge is being built to accommodate the interstate widening.
A conditional timeline
Construction on the bridge began back in late 2021, but the timeline for the project’s completion is dependent on weather and handling any unforeseen circumstances. NCDOT Communications Officer David Uchiyama says that the segmental portion of the bridge (the pieces that are being stuck together to create the basis of the bridge structure) could be completed in the next six months. Construction started on the west side of the structure and will eventually connect the east side of the bridge to the west side. As of last Monday, Nov. 27, 36 total superstructure pieces are up with 26 still to go.
However, once the segmental portion is complete, the crew will still have to construct the bridge barrier wall, overlay the deck, build the approach slab, and complete work on the approaching roadway (essentially, the parts you need to actually get onto and drive on the bridge). All of these parts of the project are also contingent on weather and project circumstances.
As soon as the new bridge is ready for traffic, the contractor will start removing the old bridge.
Let’s get technical
Now listen — we’re not engineers. But some of our readers asked about the construction method, so we’re going to break it down (with extensive help from NCDOT’s Buncombe County Resident Engineer Luke Middleton).
The bridge is being built using the segmental balanced cantilever method of construction, which was chosen by the Federal Highway Administration. Essentially, building a bridge this way starts with piers. Pieces of the bridge are put into place in pairs, with one piece going up on one side of the pier and the next piece going up on the other side of the pier (hence “balanced” in the name). So instead of the bridge being built from one side to the other or from both sides and meeting in the middle, it’s being built from each pier out. Once a pair of pieces is up, the contractor runs rebar through the top of all the pieces in place, pulling them together.
Balanced cantilever is a common bridge construction method because it’s easy to maintain, versatile, and strong.
