Locale : North America (English)
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Aerial shot of the construction

An innovative solution for Boston's Big Dig

For Boston's landmark Central Artery Project, we contributed an award-winning jacked box tunnel section that passes beneath eight active Amtrak
and MBTA railway tracks.


The Central Artery Project, known as the “Big Dig,” was conceived to cure the massive traffic congestion in the heart of Boston, Massachusetts. The elevated section of the Central Artery, which had cut off downtown Boston from the city’s North End and waterfront, was replaced with a new 8- to 10-lane highway running mainly underground.

The multilevel interchange between interstate highways I-90 and I-93 is one of the most complex sections of the project. It includes three crossings beneath eight active Amtrak and Massachusetts Bay Transportation Authority (MBTA) railway tracks serving South Station.


Mott MacDonald reviewed the preliminary design and site constraints for the crossings, and proposed an innovative tunnel jacking solution including three jacked precast concrete boxes and three jacking pits.


The solution saved millions of dollars in railway operating revenues, and has won a number of national and international awards for its ingenuity and innovation.

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