The Johnson Street Bridge will intermittently shut down for several days next month as crews lift parts into place for a long-awaited new bridge.

Tentatively starting Dec. 8 a massive crane barge known as the "Dynamic Beast," capable of lifting 900 tons, will lift steel rings and a lower counterweight into place on the new structure.

The city is letting motorists, cyclists and pedestrians know there will be "significant impacts" to traffic as the existing bridge is periodically closed to all traffic.

"These closures could be several hours in length and are necessary to ensure public safety," the city said in a news release.

The closures will occur during the first three days of work:

  • On day one, the bridge will close for 45 minutes sometime between 7 a.m. and 9 a.m. as the crane barge passes underneath.
  • On day two, it will close for 45 minutes sometime between 7 a.m. and 9 a.m. and then intermittently until 5 p.m. as the crane lifts the lower counterweight and north ring into place.
  • On day three there will be intermittent closures between 8 a.m. and 11 a.m., as well as an estimated 45-minute closure sometime between 2:45 p.m. and 5 p.m. as the barge leave the waterway.

The city says the work dates are subject to change in case of bad weather.

Those who rely on the Johnson Street Bridge should plan on using the Bay Street Bridge during the work period, the city says. Bus routes will also be altered.

The public will be able to watch the work unfold, with the best view at the northeast side of the bridge near Canoe Club and Mermaid Wharf. It will also be broadcast online on a live webcam.

The waterway under the bridge will also be closed to marine traffic while the crane barge is in place.

Work on the new structure has been ramping up after the city received its final shipments of steel from a Chinese manufacturer, and city officials say the deck span will be lifted into place in January.

The new bridge, which is nearly three years behind schedule and $42-million overbudget, is scheduled to be completed sometime in March 2018.