how you rebuild a bridge?

First, you need to drain the waterway so you can get to the footings.

In the case of the 31st Street bridge over the C & O Canal in Georgetown, built in 1867, they run the water from the canal through a series of tubes, holding containers, and pipes to give them a relatively dry section on which to work on the bridge. The wooden structure you see the water pouring back over is what the canalboat sits on when it’s not in the water.

They’ve mostly got the canal blocked further upstream because they’ve been doing repairs to the locks and the canal itself, so the water is already running pretty lightly and slowly through this section, but it was still impressive to see.

The bridge closed to vehicular traffic at the start of the summer and will remain closed until this time next year. However, they’ve built accommodations for pedestrians and cyclists to continue to get around the area, which has to be a huge relief to the couple dozen businesses and restaurants on the affected stretch of road. (It has the added benefits that the restaurants are super-excited to see foot traffic and that the two neighboring Italian restaurants often have samples of pizza at the maître d’ stands outside for passersby who might, for instance, be walking home from the movie theater.)