I would assume this is so they can move the cranes into position or something along those lines. I don't think they would be swapping out the bridge without some sort of disruption to the NEC as well, but I could be wrong:
<<Shuttle buses will replace Franklin Line train service between Dedham Corporate Center and Readville Stations on Saturday, November 5th, and Sunday, November 6th, due to Shore Line Bridge Replacement in Hyde Park.
Due to Shore Line Bridge Replacement, buses will replace trains between Dedham Corporate Center and Readville Stations in both directions on the following dates:
- Saturday November 5th, 2016
- Sunday November 6th, 2016
Customers should allow additional travel time anticipating delays of approximately twenty (20) minutes.
The following trains will be affected:
Saturday - All
Sunday - All
The following stations will be affected:
Dedham Corporate Center
Endicott
Readville>>