A digital traffic sign over Bostons Commonwealth Avenue Bridge warned, "It's coming. It's bad," before a $110-million Commonwealth Bridge westbound bridge replacement project started. Intensive construction to replace the westbound bridge is scheduled to last for slightly more than two weeks, from July 26 through Aug. 11, with completion expected by next spring.

The project to replace the deteriorating 52-year-old bridge began last July when crews completed the eastbound bridge and Massachusetts Bay Transportation Authority Green Line B portions of the bridge that opened back up to preconstruction traffic patterns three weeks early. Since then, crews have completed utility relocations, roadway and traffic-signal work, fencing, curb setting, and finishing work on sidewalks. 

Walsh Construction Co. is serving as the contractor, while the design team is led by HDR. 

Last summer, travelers were warned to expect 90-minute delays, but due to drivers heeding those warnings, officials said, it never reached those levels. 

This summer, Bostonians will feel the impact on all modes of transportation, including the Commonwealth Avenue Bridge, I-90, Boston University Bridge, the MBTA Green Line B branch and MBTA bus service.

"If possible, stay away," said Massachusetts Dept. of Transportation Secretary Stephanie Pollack at a July 24 press conference.

Travel on the MBTA Commuter Rail Worcester/Framingham line and Amtraks Lake Shore Limited line will also be impacted during the weekends of July 27 and Aug. 3.

Construction will close traffic to cars on the westbound section of the Commonwealth Avenue Bridge for 15½ days. Lanes on I-90—where between 128,000 and 145,000 drivers travel beneath the bridge on the Massachusetts Turnpike daily—will be reduced to one or two in each direction between the Allston Interchange and the Beacon Street Overpass for 9½ days.

The I-90 East on-ramp from Cambridge Street/Soldiers Field Road will be closed during the entire phase two construction period, and the Exit 20 off-ramp from I-90 West will be closed intermittently.

A statement from MassDOT spokesman Patrick Marvin reads, "While there will be significant impacts to roadway travel and diversions for public transit, pedestrians and bicyclists traveling throughout the local area will be minimally impacted."

The final phase, from Aug. 11 until next spring, will include final utility relocations and landscaping along with reconstruction of the I-90 median and repaving of I-90 from approximately the Exit 20 ramps to the Prudential Tunnel entrance. Lane closures on Commonwealth Avenue in the vicinity of the bridge will be required during this final stage.