Advocates for building light-rail lines in the Washington suburbs and Baltimore issued another study Tuesday predicting that the transit lines’ long-term job and economic benefits would far outweigh their construction and operating costs.

The analysis, sponsored by Transportation for America, is the latest released by the projects’ supporters as part of an increasingly vocal appeal to Maryland Gov. Larry Hogan’s business sensibilities as he considers the future of both rail proposals.

Hogan (R), who has called both lines too expensive as now planned, is expected to announce by mid-May whether the state can lower the costs enough to build a 16-mile Purple Line between Montgomery and Prince George’s counties. A Purple Line is estimated to cost $2.45 billion to build and $55 million annually to operate and maintain. The $2.9 billion Red Line planned for Baltimore also will be reviewed, state officials have said.

The crux of Tuesday’s report: While building both a Purple Line and Red Line would be a “significant investment,” the additional transit connections would be “a major economic shot in the arm” to Maryland, said James Corless, Transportation for America’s director. That includes thousands of jobs, as well as benefits to local tax bases as property values increased around rail stations, the report found.

Transportation for America is a project of Smart Growth America, which champions walkable, transit-oriented communities to help limit sprawl.

The 33-page report analyzed data that mostly has been published before, both in a study released in April by Montgomery and Prince George’s and in the Maryland Transit Administration’s analysis of a Purple Line’s effects.

One new figure in this analysis was that building a Purple Line would allow 91,000 additional people to live within a half-mile of a rail station.

While supporters of the two projects say the report shows they would attract jobs, spark economic development and help residents in lower-income communities reach jobs, opponents say they question the accuracy of rosy economic forecasts touted by project advocates.

Sen. Richard S. Madaleno Jr. (D-Montgomery), a Purple Line critic who has examined the state’s financing plan, said he hasn’t read Tuesday’s report. But he questioned findings that hinge on an unpredictable economy. He noted that much of the growth projected to occur near the Intercounty Connector in the Maryland suburbs stalled amid the recession.

“These are 30-year assumptions,” Madaleno said. “It’s hard to tell what’s going to happen in 30 years.”

Frank Lysy, a retired World Bank economist who writes a blog, said he found flaws in the report released last month by Montgomery and Prince George’s, some of which were repeated in the report released Tuesday. For example, he said, the reports noted that someone who rode the Purple Line’s entire length between Bethesda and New Carrollton would save 45 minutes over taking the bus. However, Lysy said, someone traveling that far probably would take Metro, which, even on an indirect route through the District, would take about as long as a more direct but slower light-rail train.

Such analyses also don’t consider the economic benefits of far cheaper transit improvements, such as upgrading the bus system, he said.