T could pour hundreds of millions into boosting Red Line capacity

A Red Line train crossed the Longfellow Bridge. Craig F. Walker/Globe Staff/File/Globe Staff

The Massachusetts Bay Transportation Authority could spend hundreds of millions of dollars on a new batch of Red Line cars, a move that officials say would possibly increase capacity on the line by about 50 percent.

Jeffrey Gonneville, chief operating officer of the MBTA, told the agency’s fiscal control board Monday that replacing 86 Red Line cars — rather than simply overhauling them — while adding additional vehicles should markedly improve service.

“We’ve seen today that upgrading the vehicles with a more modern vehicle would have a substantial impact on our system’s performance,” Gonneville said.

Expanding the fleet could mean a Red Line train would come every 3 minutes, rather than every 4.5 minutes, Gonneville said.

While preliminary, the proposal would mark a significant shift from the MBTA’s current plans. The agency has set aside about $200 million to refurbish the 86 cars and is already spending $566 million to replace nearly 300 Red and Orange line cars.

But Brian Shortsleeve, the MBTA’s interim general manager, said elected officials and customers alike have called for more capacity on the Red Line, the system’s busiest at more than 280,000 rides a day.

“We know the Red Line is booming, and we know we need more capacity,” he said. “I think one thing everyone can agree on is, more capacity on the Red Line is a good thing.”

Gonneville told the board that replacing the 86 cars and adding about two dozen more could allow the Red Line to carry 50 percent more passengers per hour. Currently, just over 20,000 customers are moved per hour, according to the MBTA.

Gonneville said officials believe that newer cars would have much better brake systems that allow cars to travel faster between stops, increasing the number of trains running at any given time. The MBTA is already replacing about 60 percent of its Red Line fleet, and the remaining cars had been scheduled for an overhaul.

MBTA officials did not estimate how much the new cars would cost, but it would likely be substantial, and comes as the agency replaces 284 Red and Orange line cars, which are being built by the China Railway Rolling Stock Corp.

That means a newer batch of Red Line cars would not be ready for quite some time. Delivery of the new Orange Line cars is slated to begin in 2018, with Red Line cars arriving the following year. The new cars should be in service by 2023, according to the MBTA.

MBTA officials would not say whether they plan to buy more cars from China Railway, or provide a timeline for the new proposal. Gonneville said that he would move forward in “exploring all options,” after presenting the idea to the board.

Gonneville also told the board that replacing the technology behind the MBTA’s outdated signal system, estimated to cost as much as $1 billion, would not improve service as much as new vehicles. The MBTA still hopes to upgrade the current signal system to a digital version, he said.

Meanwhile, the MBTA awarded a five-year advertising contract to Outfront Media Inc., which will lead to 600 more digital advertising panels across the system. The new contract will give the MBTA 70 percent of Outfront’s advertising revenue, and requires that the company pay for the new panels.

Shortsleeve also proposed a policy that would allow outside companies to provide unsolicited proposals to the MBTA for service improvements or partnerships. The policy was not meant to replace the current public procurement process, he said.

“Any proposals that we do take from the public or from other potential parties would trigger a public review process and evaluation,” he said.