Demolition of the westbound side of the Commonwealth Avenue Bridge is set to begin on Saturday.
"We really expect Saturday morning to be somewhat chaotic," Massachusetts Department of Transportation Highway Administrator Jonathan Gulliver said during a press conference Friday.
Construction on the Commonwealth Avenue Bridge began Thursday and is expected to last through Aug. 11. MassDOT officials are warning that Saturday and Monday mornings will be "very chaotic" as commuters get used to the construction site.
"If you can, avoid this area altogether," Gulliver said. "If you have to travel through the area, make sure you understand the detours. It's complicated, it impacts all modes of travel."
Not only will drivers who use the bridge be affected, but commuters who rely on public transportation in the immediate area will feel the impact, too.
The MBTA Green Line B Branch will be closed in the area. Instead, shuttle buses will be offered between Babcock and Blandford streets. Other bus routes will be detoured.
The MBTA Commuter Rail Worcester/Framingham line and Amtrak’s Lake Shore Limited will also be affected for the weekends of July 27 and Aug. 3.
"We do expect to see an additional travel time of 20 minutes," said Todd Johnson, MBTA's chief of transit services.
Gulliver described the construction as a "very active work site" and asked pedestrians and cyclists who travel near the area to take caution.
Lane restrictions for the Massachusetts Turnpike will be in effect and access to the Boston University bridge will be closed.
"We have to do this project," Gulliver said. "It's a nearly 75-year-old bridge and it's nearly at the end of its life."
Officials spent five years planning the construction and studied when it would likely be the least disruptive. Crews chose the dates for construction after studying when the area would likely see the least amount of traffic and host events.
Click here for a full list of scheduled impacts, detour routes and maps.