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This 2006 photo shows the Sagamore Bridge (US 6) over the Cape Cod Canal in Sagamore Beach. The Sagamore Bridge has a 616-foot-main span over the canal like the Bourne Bridge, but from abutment to abutment, the bridge is 976 feet shorter than its identical twin two and one-half miles to the west. (Photo by Steve Anderson.)

Type of bridge:
Construction started:
Opened to traffic:
Length of main span:
Total length of bridge and approaches:
Width of bridge:
Width of roadway:
Number of traffic lanes:
Clearance at center above mean high water:
Cost of original structure:

Steel arch
December 1, 1933
June 22, 1935
616 feet (187.8 meters)
1,408 feet (429.2 meters)
52 feet (15.8 meters)
40 feet (12.2 meters)
4 lanes
135 feet (41.1 meters)

CROSSING THE CAPE COD CANAL: Conceived since the seventeenth century by Captain Miles Standish of the Plimoth Colony, the Cape Cod Canal was completed in 1914 with the help of financier August Belmont after four years of construction. However, the original Sagamore Bridge was built in advance of the canal's opening by two years as the span had to be built before the canal was dug.

The original span spanned the canal about one-half mile east of the current bridge, and connected Gibbs Road in Sagamore Beach with Pleasant Street in Sagamore. (The southern abutment off Pleasant Street is all that remains of the old span; a house now sits atop the old abutment.) The main span comprised two 80-foot-long cantilever-bascule leaves that provided a 160-foot main span and 140 feet of horizontal clearance. However, the limitations posed by the narrow horizontal and vertical clearances - even with the lift spans in the up position - made navigating through the bridge challenging. In the closed position, the old Sagamore Bridge proved even more of a navigation hazard as it was the site of frequent ship collisions.

Despite a toll of as much as $16 for vessels, August Belmont's canal quickly became a money loser. The canal could not accommodate ships with a depth of more than 15 feet, and its swift currents and narrow width further discouraged use by larger ships. By 1915, Belmont attempted to sell the Cape Cod Canal to the Federal government. The Federal Railroad Administration acquired the canal three years later toward the end of World War I after a German submarine fired on an American tugboat, the Perth Amboy, three miles off the coast of Nauset Beach, Cape Cod.

A NEW SAGAMORE BRIDGE FOR A WIDER CANAL: In 1928, Congress directed the Army Corps of Engineers to widen and deepen the Cape Cod Canal. The Corps also was charged with rebuilding the two highway bridges and one railroad bridge connecting Cape Cod with the U.S. mainland. On September 6, 1933, the Public Works Administration (PWA) authorized the financing and construction of the three bridges under emergency legislation signed by President Franklin Roosevelt. Work on the bridges began three months later.

Like the Bourne Bridge, its twin two and one-half miles to the west, the Sagamore Bridge was built as a steel-arch span providing 616 feet of clearance between piers and a 135-foot vertical clearance. This accommodation for larger ships - and particularly Naval vessels - was critical. The Corps also accommodated the growing vehicular traffic of the 1930's by providing four lanes, double the vehicular capacity of the original Sagamore Bridge. Along with the elimination of the need for bridge openings, the new four-lane fixed span reduced travel times drastically over the old two-lane bascule span. The main difference between the Sagamore and Bourne bridges is that the Sagamore Bridge had a shorter approach. It measures 1,408 feet from end to end, 976 feet shorter than the Bourne Bridge.

The Sagamore and Bourne bridges were dedicated and opened to traffic on June 22, 1935. Its companion, the Bourne Bridge, was awarded as the "most beautiful bridge built during 1934" from the American Institute of Steel Construction.

MAINTAINING THE SPAN: The Corps began a six-year project to rehabilitate the Sagamore and Bourne bridges in 1980. The $20 million project included deck replacement, replacing of hanger cables, repaving, repainting, and installation of 12-foot-high suicide fences.

According to the Massachusetts Department of Transportation (MassDOT), the Sagamore Bridge carries approximately 55,000 vehicles per day (AADT), a volume that often doubles on summer weekends. The bridge remains under the maintenance jurisdiction of the Corps.

This 2006 photo shows the northbound lanes of the Sagamore Bridge (US 6) approaching the main steel-arch span. Note the lack of a pedestrian walkway on the bridge. (Photo by Steve Anderson.)

A PARALLEL SPAN FOR THE SAGAMORE BRIDGE: A new three-lane bridge (with a pedestrian walkway) should be built parallel to the existing Sagamore Bridge to relieve congestion. The existing bridge would be re-configured to accommodate three 12-foot-wide lanes. The twin span would be part of a new I-93 extension along the existing MA 3 (Pilgrims Highway); the I-93 designation would continue south along the existing US 6 (Mid-Cape Highway) to the proposed Southside Connector in Sandwich.

SOURCES: "Proposed Route 25 and Route 28: Final Environmental Impact and Section 4(f) Statement," Federal Highway Administration and Massachusetts Department of Public Works (1977); "Ideas Abound for Solving Cape Gridlock" by James Kinsella, The Standard-Times (10/29/2000); "Cape Cod Canal Bridges," U.S. Army Corps of Engineers (2002); Massachusetts Highway Department; Steve Alpert; Alexander Svirsky.

  • US 6 and I-93 shields by Ralph Herman.
  • Lightpost photo by Steve Anderson.




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