Even without an expansion, optimizing South Station could bring trains to Brockton every 30 minutes, according to a Boston-based transit advocacy group.

BOSTON — A new report from a Boston-based transit advocacy group blasted a potential expansion of South Station as a “$2-3 billion project of practically no transportation value,” arguing that the state could improve commuter rail frequency with much cheaper fixes to the operating schedules, tracks and train cars themselves.

South Station, located in the heart of Boston’s business district, serves as the terminal for about half of the commuter rail lines that fan out of the capitol into the Commonwealth’s suburbs and minor cities.

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State transportation officials consider the station's expansion a necessary step toward increasing the frequency of commuter rail service to transit-hungry cities like Brockton, located about 35 minutes away on the Middleboro/Lakeville branch of the commuter rail.

By expanding South Station onto a federally owned post office next door, the state could build more tracks and overcome the bottle-necking issues that limit the number of trains that can enter and exit the stub terminal each hour.

But TransitMatters, in a “proof of concept” brief published this month, argued that the state could achieve the same goals for much less money.

“The adoption of global best practice operating protocols, combined with relatively minor track upgrades, would render the South Station expansion project completely unnecessary,” the advocacy group wrote.

Instead, TransitMatters lays out specific fixes that could boost commuter rail frequency almost immediately.

The first suggestion is simply to run trains more quickly into the terminal. “At both South and North Stations, there are 10 mph speed limits for about half a mile out, which can be lifted to about 30 mph,” the brief reads.

Installing the latest track switching technology could also hasten service for a low cost, the authors write, as could dedicating specific tracks at South Station to specific commuter rail lines. The station operates today by allowing trains from all lines to reach all tracks at the station, which provides flexibility at the cost of efficiency, according to the brief.

One of TransitMatters' most impactful recommendations — electrifying the commuter rail — would require its own massive infrastructure investment though. Electrification would not only allow the trains to travel faster, the report says, it would cut down on trips out of South Station where trains travel to rail yards to refuel, freeing up valuable track time for more frequent train service.

Electrified trains are also less prone to breaking down than their diesel-powered counterparts, the report says, which would allow the MBTA to block out shorter margins of error for their operations at South Station.

Rob May, who heads Brockton’s planning department, attended a TransitMatters event last week where the brief’s authors presented their ideas.

“It looks like they can get better service without having to expand South Station,” May said Tuesday, though he believes the claims still need vetting.

Even without an expansion, TransitMatters said an optimized South Station has the capacity for trains to head down the Middleboro/Lakeville line every 30 minutes — not the 15-minute frequency touted as the gold standard in previous TransitMatters reports, but still a significant improvement.

“Every 30 minutes would be huge,” said May, whose office is seeking to attract more downtown development by pitching Brockton’s proximity to Boston, both by highway and by public transit.

The status quo, where two hours can go by mid-day without a train running through downtown Brockton, hasn’t deterred the earliest developers from buying into May’s vision, but he said better train frequency would "certainly make his job easier."

If TransitMatters is right, May said Brockton could be getting faster train service sooner than expected.

Staff writer Ben Berke can be reached at bberke@enterprisenews.com