The city of Omaha is in Nebraska. Major railroads will have to maintain two-person crews under a new rule announced Wednesday.

Railroads will be required to use two-person crews in most circumstances as they haul all kinds of cargo, including hazardous materials, according to a rule published in the Federal Register. There will be an exception to allow railroads that have already used one-man crews to use smaller crews if they can prove it is safe.

Railroads want to be able to operate trains with one person and move conductors to ground-based jobs in places with automatic braking systems. It is one of the key issues in the contract talks between the freight railroads and their unions.

Labor groups have opposed one-person crews for a long time due to their safety concerns. Labor agreements requiring two-person crews have been in place for decades at major railroads.

The proposed rule acknowledges that crew size is a safety issue at its core, according to the president of the transportation trades department coalition.

Arbitrators are listening to proposals from both sides this week as they review contract talks that have been going on for more than two years. Rail unions can't go on strike until mid September because of federal law. The recommendations can be used to negotiate a deal.

The rule will replace the patchwork of state laws on railroad crew sizes with a national standard, according to federal officials.

Pete Buttigieg said that the rule would improve safety for rail passengers and rail workers.

The Railroad Administration said there wasn't enough evidence to show it was safer than a rule that required two crew members.

A second crew member in the cab of locomotives plays a key role in making sure safety rules are followed, according to regulators.

The installation of Positive Train Control made a second person unnecessary, according to the freight railroads.

Ian Jeffries is the head of the Association of American Railroads.

New braking technology makes it impossible to regulate the number of people in a locomotive's cab.

Crash data doesn't show that two-man crews are safer, says the railroad industry The data cannot show how safe one-person crews are because most railroads use two-person crews now.

The crew size should be determined through negotiation with the unions, not by regulators, according to a Union Pacific spokeswoman. UP officials argue that moving conductors out of locomotives into a ground-based position would make those jobs more attractive because they wouldn't have to be on trains.

Railroads have struggled to hire new workers this year due to worker shortages.