Charles River Bridge (Commuter Rail)

The Charles River Bridge, referred to by the MBTA as Draw One, is a pair of railroad single-leaf, through-truss, rolling bascule bridges across the Charles River that connects North Station in Boston, Massachusetts to MBTA Commuter Rail lines in northern Massachusetts, United States.

History
Although rail bridges across the Charles River near the present location of North Station have existed since the Boston and Lowell Railroad opened in 1835, the current bridges date from 1931, when the navigable channel of the Charles River was shifted 300 feet to the north of its former route to allow the platforms at North Station to be extended northwards. These bridges were designed by Keller & Harrington of Chicago, Illinois, and built by the Phoenix Bridge Company of Phoenixville, Pennsylvania. Each bridge uses a 629 ST over-head concrete counterweight. Originally, there were four bridges, but only two of them remain.

The bridges were formerly connected to North Station by a wooden trestle; the trestle burned in January 1984, forcing all trains to terminate at a temporary station north of the river for 15 months.

The two aging two-track draw spans are planned to be replaced by three new two-track spans, which will be more reliable and have higher capacity. The unfinished sixth platform at North Station will be completed to serve long out-of-service tracks 11 and 12, the Fitchburg mainline will be slightly relocated to provide more layover space near the maintenance facility, and FX interlocking will be reconfigured. The signals contract associated with the new drawbridges was awarded in May 2019. , signal work is expected to be completed in August 2023. Design of the new vertical lift bridges began in 2019 and was 75% complete by May 2023, with design completion expected in 2024.