SPRINGFIELD - Planning is in the early stages, but a pilot program to run frequent north-south commuter trains on the "Knowledge Corridor" tracks from Springfield stopping in Holyoke, Northampton and Greenfield could begin a year from now in the spring of 2017.

Stephanie Pollack, Massachusetts secretary and chief executive officer of the state Department of Transportation, made the prediction Wednesday following a meeting with local transportation and transit planners and the mayors of Springfield, Holyoke, Northampton and Agawam.

She said MassDOT is working now on a memorandum of understanding for long-dreamed-of project with the Pioneer Valley Planning Commission.

But to earn her OK, the Pioneer Valley Commuter rail pilot project must have from the start a set time frame and a clear definition of how many riders and how much ticket revenue the trains must attract in that time period in order to be considered enough of a success to warrant making the trains permanent.

A clear definition of success is important Pollack said. In 2014, the MBTA started offering late night bus and subway service in Boston without a clear rubric.

"We are now trying to untangle that," she told reporters Wednesday in Springfield where she acted as chairwoman of the Metropolitan Planning Organization conducted at the Pioneer Valley Planning Commission.

Details for the rail demonstration project here, like frequency of service and ticket cost, still need to be worked out.

Cities and town along the route are calling for more train service on the route now served mostly by just one north-south train, Amtrak's Vermonter. That's not much traffic for a set of train tracks along the Connecticut River that the state and federal governments spent $125 million purchasing and upgrading.

The service would would make better use of the new $88.5-million rehabilitation of Springfield Union Station. It will be an intermodal bus-rail-transit hub is the highest profile rail project in the region.

The Pioneer Valley Planning Commission has a study saying frequent commuter service from Springfield to Greenfield might cost $3 million to $4 million a year in operations subsidy. That wouldn't count the cost of the actual trains which would be hand-me -down equipment from the MBTA.

Planners talked Thursday as well about the prospect of long-distance trains from Boston through Worcester and Springfield to New Haven, from Boston through Worcester and Springfield then north along the river and on to Montreal or from New Haven through the Pioneer Valley to Montreal.

That service might cost as much as $1.1 billion and might not happen until well into the next decade.

Any kind of east-west service through Springfield and Worcester to Boston, even commuter-type service , is hard to achieve because those tracks are owned by CSX and very busy with freight traffic. Also South Station in Boston needs to be expanded.

At the meeting, Springfield Mayor Domenic Sarno said east-west commuter service would help Springfield, with its relatively low housing costs, take advantage of a costly housing crunch in Boston and its near suburbs.

Massachusetts is developing statewide passenger and freight rail plans and a five year capital project plan, Pollack said.

And she wants everyone to start thinking of transportation not in terms of roads versus trains versus bicycle paths. instead thinnk of networks.

"A comprehensive rail program might do a wonderful job of getting someone to the rail station ," she said. "But the rail station is not their final destination. After that they need to get their car, or get on a buds or grab a bike to get where they are going."

Mary MacInnes, administrator of the Pioneer Valley Transit Authority, said her bus operation is happy to hear of more rail service.

"Because then we get another job," MacInnes said. "We then become the feeder system."

MacInnes has said she expects bus ridership to increase when Springfield Union Station with its parking, security and amenities becomes the hub of its local system.