The U.S Army Corps of Engineers is recommending that the Bourne and Sagamore bridges to Cape Cod be replaced, according to its long-awaited study released Thursday.

The federal agency is looking to design two new bridges that would be built parallel to the existing bridges to minimize the impact on area residents and businesses. They would each have four travel lanes, each 12-feet wide, two of which would be through travel lanes and one "acceleration/deceleration lane in each direction,” according to the study.

The new bridges would also have a pedestrian and bike lane with separation from the vehicular traffic lanes. The existing bridges, built more than 80 years ago, would be demolished after the new bridges open.

Were officials to pursue rehabilitation instead of replacement, the work would require roughly 310 days of full bridge closures across two years of work, scheduled for 2025 to 2027 for the Sagamore Bridge, and 2029 to 2031 for the Bourne Bridge, respectively.

Total transportation delay costs over the 50-year period associated with the rehabilitation plan would be over $2 billion for both bridges, the study says.

“This study has determined that providing two new highway bridges would be the most cost effective means of providing safe and reliable crossings,” the study says. “The existing bridges are 85 years old and are functionally obsolete.”