Replacement Bonner Bridge under construction, showing precast box girders for the navigation spans.
In spite of severed power lines and some very unexpected winter storms the replacement span for the Bonner Bridge is still on target for a November opening. Since that’s clearly within the one year range, this seems like a good time for an update.
There is no doubt the new bridge is larger. Driving past the construction zone, the Bonner Bridge seems miniature by comparison.
There’s a couple of reasons for that. Certainly the replacement bridge is higher, but that’s not the only reason it seems so much larger. It’s also higher for much longer.
The Bonner Bridge has one navigation span that’s 130’ wide. The new bridge has seven averaging 300’.
The navigation span structures look like something from a futuristic construction project. They look a little bit fragile, as though they could just tip over. They won’t, but that’s there appearance.
It’s a precast box girder construction. The way it works is a precast box is put on the north and south side at the same time so the navigation span platform is always in balance.
The original bridge had a planned 30 year lifespan. Since we’re now into year 55, the bridge has exceeded expectations. Nonetheless, it is an aging bridge and maintenance costs are skyrocketing.
The new bridge has a planned life of 100 years and there are a number of things being done differently to achieve that.
The pilings that support navigation spans have been pounded anywhere from 100-140’ into the ground, and utilize construction techniques that will mitigate scour—the action of strong current and sand against a solid object.
Probably the most innovative use of material is the stainless steel rebar to reinforce the concrete used throughout the bridge.
If all goes as planned—and it looks as though it will, the bridge will open for traffic in November of this year. The project will wrap up in September of 2019 with the demolition of the old bridge, leaving 1000’ on the Pea Island side as a fishing pier.