Deficient I-90 Viaduct Replacement Project Could Start In 2020

Construction would begin in three years to replace a structurally deficient viaduct that carries 144,000 vehicles a day along Interstate 90, over Boston's Allston neighborhood, according to plans outlined by state officials on Monday.

"The time has come to move this project forward through the design phase so it can be built," MassDOT chief highway engineer Patricia Leavenworth said in a statement released after state transportation and MBTA officials received a presentation on the I-90 Allston Viaduct project.

One version of the project is at the 15 percent design phase and the current schedule calls for preliminary design to be completed in 2019 and construction to begin in 2020 after a contractor is selected. The state estimates it spends $800,000 a year to maintain the viaduct, which was built in the 1960s and also impacts commuter rail and Amtrack service and individuals traveling on foot or by bicycle.

Officials listed three options under consideration: replacing the viaduct and shifting the railroad beneath the structure while keeping the railroad at grade; removing the viaduct and replacing it with an at-grade highway and building a railroad viaduct; removing the viaduct and replacing it with an at-grade highway and keeping the railroad infrastructure at-grade.

Project options range in estimated price from under $500 million to more than $1 billion. State officials said they are analyzing financing options.