Bourne Bridge

The Bourne Bridge and the Sagamore Bridge were built in 1933, and they changed the relationship between Cape Cod and the rest of Massachusetts. This was the first time that cars could easily travel to and from the Cape, which allowed Cape residence to access jobs on the mainland and launched a new tourism industry. Interestingly, these bridges are owned and maintained by the U.S. Army Corps of Engineers, not State Highway Administration.

The Cape Cod Canal itself was first discussed all the way back in the 1620’s. Numerous feasibility studies were done over the years, and some groups actually purchased the charter and began construction. However, they all ran out of money or were overwhelmed at the enormity of the project, and abandoned it. It wasn’t until 1904, when August Belmont II purchased the charter, that any real progress was made on the canal. He broke ground on June 22, 1909, and the canal was opened on July 29, 1914. This is notably 17 days before the Panama Canal opened on August 15, 1914. However, work continued on the canal to increase the depth, and it was not officially opened until April 10, 1916.

The original Buzzards Bay Railroad Bridge was built as a single span bascule bridge in 1910. The original Bourne and Sagamore Bridges were completed in 1911 and 1913 respectively. These were both moveable bridges, which consisted of two eighty-foot cantilever spans. All three of the bridges were electrically operated, and provided a navigational opening of 140 feet. This narrow opening soon proved to be a navigational hazard for vessels moving in the Canal’s swift currents. There were numerous serious accidents in the canal, which cause lengthy closures. The canal never saw level of traffic that Belmont and the investors envisioned, and the canal was ultimately a financial failure.

In 1927, the Cape Cod Canal was sold to the Federal Government, and Congress directed the U.S. Army Corps of Engineers to operate and improve the canal. One of the main problems with the canal was the bridges. The bridges were typically left in the lowered position, which required boats to fight the swift current while they waited for the bridges to open. Therefore, the Corps began a project to replace the bridges with elevated, fixed span bridges. At the same time, the railroad lift bridge was replaced. This allowed the canal to be deepened and widened from 1935 to 1940. At that time, it was the widest sea level canal in the world.

Construction started on the new Bourne and Sagamore bridges in 1933. The new bridges both have a main span of 616 feet, and a vertical clearance of 135 feet above high water. Although the bridges are very similar, they differ slightly in the number of approach spans. The Bourne Bridge was built on a flatter terrain which required some deck truss approach spans. In contrast, the Sagamore Bridge was built near some natural hills, which eliminated the need for the deck truss approach spans. The Sagamore Bridge also has a concrete span over Sandwich Road. Both bridges carry four lanes of traffic and have a 40-foot roadway width. They were dedicated simultaneously on June 22, 1935.

Both bridges underwent a major rehabilitation project in 1980. This project included replacement of the bridge decks, repaving, repainting, and installation of twelve foot high suicide deterrent fences. The hanger cables were replaced on the Sagamore Bridge. The cables on the Bourne Bridge weren’t replaced until 1986.

Both the Sagamore and Bourne Bridges are functionally obsolete, and struggle to carry the volume of traffic that is required. In 2020, the Corps recommended replacing both bridges with new, wider, bridges to alleviate the traffic congestion. However, this project is struggling to move forward due to cost associated, which is currently estimated at $4 billion. MassDOT failed to secure federal funding for the project, and as of 2023, application for three separate discretionary grant programs had been rejected. MassDOT is progressing the concept development engineering design for the project. In 2022, they published a number of options, including the preferred alternative. The new structures will likely be arch bridges in a similar style to the existing structures. Each bridge will be replaced with twin bridges, one for each direction of travel. There will be two 12-foot travel lanes, a 12-foot entrance/exist lane, a 10-foot shoulder and a 4-foot shoulder on each bridge. There will also likely be roadway improvements on either side of the canal, but the full scope has not yet been developed, and this is not included in the projected project cost