Federal officials and lawmakers have worked out a deal to fund and rebuild the landmark, but deteriorating, Arlington Memorial Bridge in Washington, D.C., using design-build to cut 18 months from the schedule and $35 million from an earlier cost estimate.

In announcing the agreement on what is now pegged as a $237-million plan, the Interior Dept. also said it had awarded a $192-million contract to Kiewit Infrastructure Co. to construct the project. Interior’s National Park Service owns and maintains the 85-year-old bridge.

The other $35 million of the price tag is for engineering, construction management, wetlands mitigation and contingency funds, which Interior says will be handled through the Federal Highway Administration.

The Virginia and District of Columbia congressional delegations have been pushing for funds for the project for the last few years. That push led to a $90-million FASTLANE grant from the U.S. Dept. of Transportation for the project. Virginia’s senior U.S. Senator, Mark Warner (D), also is credited with getting an additional $30 million for the bridge upgrade in the fiscal 2017 appropriations measure.

The new piece of the puzzle is $107 million from the park service. It was not immediately clear whether all of that would be in fiscal 2018 funds or spread over the project’s three-year construction schedule.

Interior Secretary Ryan Zinke said, “The bridge is one of the largest transportation infrastructure projects in National Park Service history.”

Warner said that a joint effort among members of Congress, the D.C. government, park service and U.S. DOT produced the deal.  He added, “These partnerships allowed the park service to design an innovative project that will save money and time for the region’s commuters and visitors."

Minor repairs will begin in early 2018 on the 2,163-foot-long, 60-ft-wide bridge, which crosses the Potomac River; major construction is expected to start that fall. The project is to be completed in 2021, according to the region’s congressional delegation.

The lawmakers noted that at least three lanes of the bridge will be open to traffic while construction proceeds.

The park service and FHWA have been making emergency repairs to the bridge over the past six years. But unless the bridge gets a complete overhaul, Interior said, the structure’s condition will worsen and it will need to be closed by 2021.

The Memorial Bridge was designed by McKim, Mead and White and opened in 1932. Interior says that, at that time it was “the longest, heaviest and fastest-opening drawbridge in the world.” But the last time its bascule section was opened was in 1961.

The new work will include replacing the bascule span with variable-depth steel girders, rehabilitating concrete approach spans and replacing the concrete deck. The project team will use accelerated bridge construction methods, such as using prefabricated concrete deck panels, according to Interior.