Replacing a highway bridge, even a small one, is a big deal. Engineers have figured out how to turn that big deal into a small deal, or at least a quick one. A new bridge by morning, almost. Today, on Engineering Works!
Bridges carry traffic over something that’s in the way. A river. A valley. San Francisco Bay. Closing a bridge for months or even years while we build a new one is more than an inconvenience. It costs money.
Now engineers have put together a package of technologies and building techniques they call, accelerated bridge construction, that turns replacing a bridge from a long-term disruption to almost an overnight interlude.
For instance, small bridges, like many that carry urban streets over streams or other streets, can be assembled somewhere else and moved to the site in one piece, like picking up Legos and putting them down somewhere else. Engineers in Boston did this a while ago between Friday night and Sunday afternoon. They hauled in the new bridge, all 400 tons of it, and set it into place with cranes.
On the other end of the scale, engineers are replacing decking on the Golden Gate Bridge in 25-foot-wide prefabricated sections. The bridge keeps carrying traffic with the smallest of traffic disruption. Engineers in Massachusetts replaced 14 bridges on an interstate highway in 10 weekends. No sweat.
We’ve come to the end of our bridge for today and it’s time to pull over. See you next time.
Engineering Works! is made possible by Texas A&M Engineering and produced by KAMU-FM in College Station. Learn more about engineering. Visit us on the World Wide Web.
Start the discussion: We don’t think about bridges very often unless one we use is closed. Then we think about it a lot. This kind of construction can take a lot of the inconvenience out of keeping infrastructure up to date.