Unions and freight railroads said on Monday they have struck contract deals covering 15,000 workers after U.S. President Joe Biden named an emergency board to help reach agreements.

The National Carriers' Conference Committee (NCCC), which represents U.S. freight railroads in national collective bargaining, said deals had been struck with the Transportation Communications Union/IAM, Brotherhood of Railway Carmen, and International Association of Machinists and Aerospace Workers representing more than 15,000 rail employees.

The deal implements recommendations by the presidential board.

The International Association of Machinists and Aerospace Workers (IAM) Rail Division said the 24% compounded pay raise over the five-year contract would be the largest ever if ratified.

On Aug. 16, the emergency board tasked with helping major freight railroads and unions end a contract negotiation stalemate proposed annual wage increases of 3% and 7% from 2020 to 2024 equal to a 24% compounded hike. The board also recommended five $1,000 annual bonuses and an additional paid day off.

"We fought side by side against the carriers' attack on wages and healthcare benefits," IAM's Josh Hartford said in a statement

Talks between 30 major freight railroads, including Union Pacific, Berkshire Hathaway-owned BNSF and CSX, and unions representing 115,000 workers have dragged on for more than two years.

Nine of the 12 unions have yet to reach contract agreements.

Biden appointed the three-member presidential emergency board in July to reduce transportation-related disruptions that stoke inflation and threaten supplies of food and fuel.

Rail service at major U.S. seaports has suffered recently due to spreading supply-chain snarls and labor and equipment shortages.

Under the Railway Labor Act, carriers and unions remain in a 30-day cooling off period that expires just after midnight ET on Sept. 16.