Metro’s board of directors is expected to vote Thursday on service changes to the Blue and Yellow lines intended to address overcrowding on the Orange Line and to make way for new rail service in Northern Virginia.

The “busiest place anywhere on our system during peak periods” is on the Orange Line between the Courthouse and Rosslyn stations, said Metro chief spokesman Dan Stessel. During rush hour, the line is often called the “Orange Crush,” he said.

It becomes worse — and potentially dangerous — when a train malfunctions or an accident occurs during rush hour, such as when a man was struck by a train Tuesday afternoon. That incident caused station closures, hours of delays and the dispatch of emergency personnel to Rosslyn, which was overwhelmed by the crowds.

To try to offset normal crowding and to make way for new service on the Dulles rail line, some trains on the Blue Line, which shares some Orange Line stations, would be routed across the Yellow Line bridge over the Potomac beginning in June, Stessel said. The first phase of the Dulles extension is scheduled to open in late 2013.

Stessel said that the changes are expected to benefit more than 108,000 customers but that 16,000 passengers who connect in Rosslyn and head west would have to wait six minutes more for a Blue Line train.

The changes would add more than 2,600 seats during peak periods on the Orange Line, Stessel said. It would also give customers at the Pentagon station and those to the south “faster service to downtown,” he said.

Metro is redesigning its iconic map to depict the changes, which would be indicated with dashes on the colored lines. The transit authority expects to replace more than 2,600 signs, install 5,000 new maps and switch out 1,200 fare charts throughout the system.

Metro estimates that implementing the changes, including educating riders, will cost $3.1 million.

While Metro is redoing its map, the board has implemented a policy to keep station names short, with a recognizable primary name and a longer secondary name. The board is also expected to vote on those changes.

Among the new names: Old Town would be added as the secondary name for the King Street stop; Ballpark would be added to the name for the Navy Yard station; and a blue capital letter H would be added as an identifier for stations near major hospitals, including Forest Glen, Medical Center, Foggy Bottom and Shaw.

On Thursday, Metro’s board will also hear a presentation on whether to change the transit network’s complex fare structure as it prepares to implement a new electronic payment system in the coming years.

Metro plans to install new technology for payment methods that would eventually replace its SmarTrip electronic fare cards, which officials say are outdated. Passengers would be able to use credit and debit cards to pay at the fare gates.

Stessel said there are currently more than 44,000 combinations for fare costs.