This 1881 plate girder crossing consists of two plate girders each 4'-6" deep with 11-inch flanges. Evidently the masonry was insufficiently strong to support the weight, and in 1908 two wood-pile bents were inserted beneath the plate girders. These are still in place. The plate girder bridge at 22.24 is virtually identical, and had the same repairs in 1908. The latter bridge is four feet shorter.
The first plate girder bridge is believed to have been constructed in the U.S. in 1846-47; in Massachusetts, Edward S. Philbrick, engineer for the Boston & Albany Railroad first designed a plate girder for that line in 1860. The B&A bridges have all since been'replaced. This example, and its companion at milepost 22.24, are the oldest identified plate girder spans in the state."
-P.H. Stott, MBTA Historical Property Survey Phase II, 12/1987