The MBTA's plans raise the possibility that the extension of the Blue Line, a goal of Lynn officials for more than a half century, might finally be gaining traction. The Blue Line, one of the MBTA's four rapid transit lines, currently terminates at the Wonderland station in Revere.

The MBTA expects to complete an environmental study of five alternatives this April or May for addressing the public transit needs in the corridor between Revere and Salem, according to Dennis DiZoglio, the agency's assistant general manager for planning and real estate.

DiZoglio said the study, which also includes cost and other issues, will identify the option the agency would like to pursue. He said the MBTA will look to US Representative John F. Tierney of Salem to try and have funding authorized for the project in a multiyear federal transportation spending bill that is expected to be taken up by Congress this fall.

While no options have been ruled out, DiZoglio said the MBTA is likely to choose from among three. Two of those involve extending the Blue Line from Wonderland station north to Lynn and possibly Salem. The third involves building a new commuter rail station near Wonderland and providing a way to transfer passengers between that stop and Wonderland station.

The two other options are to do nothing, and to expand service on existing commuter rail and bus lines.

The MBTA plans to hold a public meeting, probably in February, to provide an update on the study, and another public meeting after the study is complete.

Even if the project is included in the federal transportation bill, there is no guarantee of federal funding - the MBTA would still have to apply for a grant. The agency would have to follow a similar process to secure funding from the state to cover its share of the project. DiZoglio estimated the overall project would cost $200 to $400 million, of which the state would be responsible for 40 to 50 percent.

DiZoglio said the steps the MBTA is taking represent ''the most logical way to approach'' getting a Blue Line extension or alternative project accomplished.

''Clearly, there is not going to be sufficient local funds to do the project. We're going to have to have an infusion of federal dollars. Previous efforts didn't pursue the federal dollars as logically as we are doing,'' said DiZoglio, who was formerly mayor of Methuen and community development director in Peabody.

DiZoglio said the two options for extending the Blue Line being explored by the study would be to run the line from Wonderland through the Point of Pines section of Revere, and to run it alongside the existing commuter rail line. Yet to be decided is whether the extended line would terminate in Lynn or go on to Salem.

Salem Mayor Stanley J. Usovicz Jr. said he strongly supports extending the line to Salem.

''It clearly opens up the North Shore and in a way that connects us not only to Boston proper but in particular to the airport,'' he said.