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MBTA - Fort Pond Brook Bridge (MP 25.03)



"The single track Fitchburg Railroad main line reached Waltham in December 1843, Concord in June 1844, and Fitchburg in March 1845. Construction of a second track began in 1845 and was completed in 1849. The Boston and Maine Railroad obtained control of the Fitchburg Railroad in 1900 and the MBTA purchased the section between Boston and Fitchburg in 1976.

This is a skewed, triple track, single span, filled spandrel, stone arch bridge. The original arch is constructed of rough-cut stone blocks 24 inches thick as evidenced by the ring stones at the spandrel. The clear span of the arch is 20'-0". The springline is approximately five feet above the mudline, and the rise of the arch is approximately ten feet. The bridge appears to have been constructed in three phases, based on an examination of the barrel vault. The earliest bridge appears to have been 32'-8" wide, while a widening of the bridge added another 12'-4" to the width on the south side. Most recently, a 9-foot pedestrian walkway, supported by brick piers was added to the north side of the arch. Spandrel walls are rough coursed ashlar granite stone. The voussoirs are uniformly cut and shaped. On one side of the arch, two tapered brick piers carry the pedestrian walkway and serve to buttress the arch.

The original 32-foot deep arch may date to the original construction of the line. If so, the additional arch width may date to the late 1840s."

-Peter Stott, MBTA Historical Property Survey Phase II, 9/1988


Stone arch bridge over Fort Pond Brook on MBTA Fitchburg Line
Acton, Middlesex County, Massachusetts
Open to traffic
Built 1845
- Boston & Maine Railroad (BM)
- Commuter Rail
- Fitchburg Railroad
- Massachusetts Bay Transportation Authority (MBTA)
Stone arch
Length of largest span: 20.0 ft.
Total length: 23.0 ft.
Deck width: 45.0 ft.
Also called
B&M Fitchburg Division Main Line Bridge No. 25.03
Approximate latitude, longitude
+42.46003, -71.45288   (decimal degrees)
42°27'36" N, 71°27'10" W   (degrees°minutes'seconds")
Approximate UTM coordinates
19/298322/4703770 (zone/easting/northing)
Quadrangle map:
Inventory number
BH 67517 (Bridgehunter.com ID)

Update Log 

  • May 10, 2015: Added by Ian Martin