The Massachusetts Bay Transportation Authority could potentially increase capacity on the busy Red Line by about 50 percent if it spends millions of dollars on new train cars.

MBTA Chief Operating Officer Jeffrey Gonneville told the MBTA’s fiscal control board on Monday that spending the money to replace 86 cars rather than repairing them while adding additional vehicles would greatly improve service, according to The Boston Globe.

The MBTA is already replacing about 60 percent of its Red Line fleet, and the remaining cars had been scheduled for an overhaul, at an expected cost of about $200 million. MBTA officials didn’t provide an estimate for how much replacing the cars would cost.

Officials think that newer cars would have much better brake systems that allow them to travel faster between stops, increasing the number of trains running at any given time, Gonneville said.

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

The Red Line is the system’s busiest at more than 280,000 rides a day, MBTA General Manager Brian Shortsleeve said.

Gonneville told the board that replacing the technology behind the MBTA’s outdated signal system, estimated to cost as much as $1 billion, would not improve service as much as new vehicles.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.