Longfellow Bridge

Longfellow Bridge
Bridge as seen from the Prudential Tower observatory
Coordinates	42°21′42″N 71°04′31″W / 42.361635°N 71.07541°W / 42.361635; -71.07541Coordinates: 42°21′42″N 71°04′31″W / 42.361635°N 71.07541°W / 42.361635; -71.07541
Carries	Route 3, MBTA Red Line
Crosses	Charles River
Locale	Boston, Massachusetts to Cambridge, Massachusetts
Maintained by	Massachusetts Department of Transportation
Characteristics
Design	steel rib Arch bridge
Total length	1,767.5 feet (538.7 m)
Width	105 feet (32 m)
Longest span	188.5 feet (57.5 m)
History
Construction begin	July 1900
Opened	August 3, 1906
Statistics
Daily traffic	28,600 cars and 90,000 mass-transit passengers

The Longfellow Bridge (also known to locals as the "Salt-and-Pepper Bridge" due to the shape of its central towers) carries the Route 3 roadway, the Massachusetts Bay Transportation Authority Red Line trains, bicycle, and pedestrian traffic. The structure spans the Charles River to connect Boston's Beacon Hill neighborhood with the Kendall Square area of Cambridge, Massachusetts. The structure was originally known as the Cambridge Bridge, and a predecessor structure was known as the West Boston Bridge; Boston also continued to use "West Boston Bridge" officially for the new bridge.

The bridge falls under the jurisdiction and oversight of the Massachusetts Department of Transportation (MassDOT). The bridge carries approximately 28,600 cars and 90,000 mass-transit passengers every weekday. A portion of the elevated Charles/Massachusetts General Hospital rapid transit station lies at the eastern end of the bridge, which connects to Charles Circle.

Longfellow Bridge is a combination railway and highway bridge. It is 105 feet (32 m) wide, 1,767 feet 6 inches (538.73 m) long between abutments, and nearly one-half mile in length, including abutments and approaches. It consists of eleven steel arch spans supported on ten masonry piers and two massive abutments. The arches vary in length from 101 feet 6 inches (30.94 m) at the abutments to 188 feet 6 inches (57.45 m) at the center, and in rise from 8 feet 6 inches (2.59 m) to 26 feet 6 inches (8.08 m). Headroom under the central arch is 26 feet (7.9 m) at mean high water.

The two large central piers, 188 feet (57 m) long and 53 feet 6 inches (16.31 m) wide, feature four carved, ornamental stone towers that provide stairway access to pedestrian passageways beneath the bridge. Its sidewalks were originally both 10 feet (3.0 m) wide, but as of 2013^[update], for unknown reasons, the upstream sidewalks were narrower than the downstream ones.