Oops: Engineering goof delays work on Comm. Ave. bridge over turnpike, but that's good news for turnpike drivers

State officials say they've had to push back replacement of the aging Comm. Ave. bridge over the turnpike by a year because of design mistakes by an engineering firm working on the project.

The delay, however, means the state is increasing the number of open lanes in each direction on the turnpike under the bridge from three to four lanes.

Officials had initially hoped to shut parts of the road, the Green Line, the turnpike and the commuter-rail line in two periods this July and August, when BU would be out and the Sox wouldn't be playing, for an $82-million replacement bridge.

Last summer, the state had to shut the Green Line when a pothole started growing on the bridge.

According to MassDOT:

This past January, MassDOT was notified by Walsh Construction that design errors on the part of their engineering firm of HDR Inc., have resulted in fabrication delays, and Walsh Construction would be unable to meet the dates established for the 2016 closure phase.

In a statement about this postponement, Walsh Construction said, "During the final bridge design quality control checks, two issues related to the design of the new structural steel girders were encountered that required revision and modification to the final steel girder design. As a result, the fabrication of the new steel girders is not able to be conducted as originally contemplated to meet a shutdown in the summer of 2016. However, in conjunction with MassDOT and our designer, we have resolved these issues and look forward to successfully completing the first phase of the project in the summer of 2017."

MassDOT has decided to postpone the two closure phases of the project by one year to July and August of 2017 and 2018, respectively. Walsh Construction will forfeit the $7.2 million incentive tied to successful completion of the 2016 closure phase.

The postponement means I-90 drivers will see some short-term traffic relief. MassDOT is currently in the process of reconstructing the I-90 median in the vicinity of Commonwealth Avenue, which included performing advanced work for the Commonwealth Avenue Bridge Project. This project has required reducing I-90 from four travel lanes to three. Under the previous schedule this three lane configuration would have been maintained until the beginning of the first shutdown in August 2016. Due to postponement, I-90 will be opened back to four lanes as of June 30, 2016 and remain four lanes until the beginning of the first shutdown now rescheduled for July 2017. Traffic will be reduced from four lanes in both directions to two lanes in both directions during July 2017 and August 2017.

The new span is now scheduled to carry traffic in September, 2018.