Among the numerous proposals before the legislature this year are suggestions for the extension of the rapid transit system serving the Boston metropolitan area. There can be little doubt today that some new facilities are needed if the city is to escape an asphalt death.

The proposed extension of the MTA subway along Massachusetts Ave. from Harvard Square to Porter Square is particularly welcome, and especially timely. The most practical plan calls for the line to continue on above ground from Porter Square to West Cambridge, and from there two branches would go on to Weston and Bedford. Both routes would intersect Route 128, the main highway circling Boston.

Service to Bedford would in effect, provide an alternative air terminal facility at the Air Force's Hanscom Field. In the event that Logan Airport is fogged in, liners are currently diverted to Hartford-Springfield, Nantucket, or even New York fields, and cannot use the nearby Bedford installation. Rapid transit along the Boston and Maine trackage would aid travellers by making a second jet-age facility available for commerical airliners.

Perhaps the most important consequence would be relocation of the MTA yards and shops which would follow the elimination of most of the surface lines running into Harvard Square and the transfer of terminal facilities to West Cambridge. The University has offered to help pay the cost of relocation if it can acquire the yards for its own expansion.

Also significant is the prospect of relieving congestion if busses and trolleys disappear and the Square ceases to be an all-day parking place for subway users. The improvement of service to outlying areas (currently there is only one train a day in each direction to Bedford) will greatly relieve the floods of automobiles that daily inundates Boston and Cambridge. The large parking and terminal facilities planned for the West Cambridge junction should also go a long way toward alleviating the Cambridge parking problem.

Opponents of the extension have stressed its cost, already estimated at $20 million, and almost sure to go higher. But while the initial costs are great, the improvement will permit substitution of profitable rapid transit operations for deficit-producing bus and trolley routes--a very appealing argument since the MTA was $15 million in the red last year.

The legislature must resist the temptation to procrasinate by merely ordering another in the interminable sequence of favorable studies going back to the Coolidge reports of 1945 and 1947. In fact, MTA extension has already been initiated, and an extension to Newton Highlands is now under construction.

If previous reports were not sufficient reason for speed, the legislators should also remember that the MTA's reserve on land in West Cambridge expires in 1961. Moreover, Massachusetts Ave. will be widened this summer, and co-ordinating this work with construction of the subway would permit sharing of expensive relocation of the public utilities which run under the road. Just a look at the present situation in Harvard Square should convince even the economy-minded that any opportunity should be seized.