Growth from rails limited, study says

Neither the share of workers who use mass transit nor the density of development increases significantly when commuter rail service is expanded, according to a report set to be released today .

The study, conducted by the Rappaport Institute for Greater Boston at Harvard University, questions some of the key "smart growth" arguments for spending hundreds of millions of dollars on commuter rail to promote development that encourages the use of public transit.

The report concludes that "large investments in commuter rail have had . . . modest positive impacts on ridership and land uses."

Eric Beaton , the author of the report and a graduate student at Harvard, studied areas within 5- and 10-minute drives of the 160 current or former commuter rail stations in Greater Boston.

Beaton found that the 100 areas that had kept or gained commuter rail service after 1970 had roughly the same share of commuters who were using mass transit as the 49 areas that lost rail service.

Instead, ridership has followed general national trends, the report says.

The study also found that most of the land use around the station has not changed in 35 years.

"About 90 percent of the land has basically been what it's always been," said David Luberoff , executive director of the Rappaport Institute.

"[A commuter rail station] can be something that's helpful, but if you're really trying to change land uses, you have to change land uses," he said. "You can't induce them with commuter rails."

Luberoff said commuter rail stations have some positive effects on their surrounding areas.

"When I think about this as an investment, I say there's some positive impact from this, but let's not go overboard," he said.

The state is planning a $479 million restoration of the Greenbush line along the South Shore from Weymouth to Scituate, and is proposing to extend the Stoughton line to Fall River and New Bedford at an estimated cost of $670 million.