The jobs would be a combination of construction-related jobs and positions created through the economic development the proposed 16-mile light rail line is expected to generate in the areas it would serve -- which stretches from New Carrollton to Bethesda and includes College Park and Silver Spring, he said.
Though Madden acknowledged that the estimates "are extremely high," he said they are based on the experiences of cities with established light rail lines.
The rail system's 21 stations would connect all three MARC commuter lines with Metro's Red, Green and Orange lines, Amtrak and local bus systems, Madden said. About 30 percent of the estimated 60,000 daily riders are expected to use Metrorail for part of their trip.
"I'm very hopeful on the Purple Line," said Montgomery County Councilman Hans Riemer, D-at large. "It has tremendous potential for economic development for the region" and could be "game-changing."
Whatever the benefits, some won't be felt until 2015, when construction is scheduled to begin, and many of them won't begin to be realized until the system is completed in 2020.
But first, the $1.925 billion project must be funded.
The Maryland Transit Administration has $30 million in state funding in the current fiscal year and $38 million next fiscal year "to keep the project on schedule," Madden said. But additional federal and state funds are not guaranteed.
Montgomery and Prince George's officials probably will need to rely on private funding to complete the system, Montgomery County Executive Ike Leggett told state lawmaker two weeks ago.
"Developing and maintaining transportation infrastructure is a partnership," he said, including the Purple Line in a list of county transportation projects that together could cost as much as $4 billion.
The Federal Transit Administration has urged the Maryland Transit Administration to consider partnerships with the private sector, Madden said.
Residents who want to voice opinion or learn more about the Purple Line can attend a meeting at 5:30 p.m. on Monday at the Silver Spring Civic Building or on Thursday at Beacon Heights Elementary School in Riverdale.