One out of every five people commuting to Boston enters the city by way of Route 3, better known as the Southeast Expressway and officially designated part of I-93, in the nation's Interstate Highway System.
The 8.3-mile stretch of eight-lane road between the Route 128 beltway and the Massachusetts Avenue exit in Boston - New England's most heavily traveled stretch of road - has been declared in ''severe deterioration'' by a special inspection group. And commuters have been disturbed by its monumental traffic jams, which stall as many as 100,000 vehicles at one time.
To correct these problems, the Massachusetts Department of Public Works (DPW) has authorized a $65 million contract to reconstruct the expressway's 15 bridges and to resurface the roadway. Work will begin March 19. The project is to be completed by September 1985. That's the good news.
The bad news is that reconstruction will mean more frequent, intolerable traffic jams for the 165,000 vehicles that travel the expressway each day, more than twice its original 80,000-vehicle capacity.
A number of communities, including Quincy, Dorchester, and Milton, have pressed to have the road widened. So why not delay the repair project until plans to increase expressway capacity can be drafted?
''We can wait no longer to repair the throughway,'' says Robert T. Tierney, commissioner of the Massachusetts Department of Public Works, the state agency responsible for rehabilitation of the strip. ''The bridges should have been renovated three years ago. Conditions are so bad we can't guarantee that some sections will not crumble if we wait.''
Leaders of the Metropolitan Area Planning Council (MAPC), an advisory body, support the massive road repair - a project that will be 90 percent federally financed - adding that expansion is not feasible now.
When the Southeast Expressway was completed in 1959, it was thought to be the ideal commuters' road into a major city, its modern construction able to move vehicles nonstop in and out of the Hub. The road, now with rusting steel girders and eroding concrete, is in stages of disrepair because of ''overuse and spotty upkeep,'' Commissioner Tierney says.
He opposes expanding expressway capacity because too many residents in the crowded communities of Quincy and Dorchester would have to be moved to make room for added lanes, and it would cost too much money and cause too much public anguish to acquire the needed properties. ''And we find no support for another proposal, second decks for some of the bridges,'' Tierney adds.
A report issued Feb. 14 by the MAPC says the DPW has spent $7 million to maintain concrete bridge decks, $3 million to resurface roads, and $4 million to fix potholes in the last 10 years. A majority of the bridges ''cannot be fixed with stopgap measures.''
The expressway repairs will include more lighting; roadway construction built to last 20 years without need of repair; and completely rebuilt and redesigned bridges.
State and federal funds are being used to aid local communities cooperating with programs to ease expressway traffic problems during the reconstruction period, Tierney says. But communities are concerned that as commuters seek alternative routes traffic will increase on their streets, which were not designed for such heavy use.
''We're planning for the best, but preparing for the worst,'' says state Sen. Paul D. Harold, whose district includes Quincy, Braintree, Holbrook, and Avon, all tied to the expressway.
He just wants to get the repairs over with. ''We have a built-in incentive to get the project completed on time: a $10,000-a-day bonus to the contractor for each day completed ahead of schedule, or a $10,000-a-day penalty for failure to complete the contract on time.''
Jean Christensen of Marshfield works in downtown Boston and commutes the final 8.3 miles of her 31-mile journey on the Southwest Expressway. ''Construction will place a terrible burden on people like me. My one-hour drive may stretch into two hours.''
Mrs. Christensen has already decided on an alternative route: She drives to Braintree, parks her car in a Massachusetts Bay Transportation Authority (MBTA) lot, and catches the rapid-transit line to her office.
Planners suggest these commuting options:
Mass transit. The MBTA will provide three additional trains on the Red Line (an extra capacity of 800-1,000 passengers.) It also is prepared to provide express-bus service to the South Shore area. In addition, the MBTA and DPW are providing subsidies to encourage private bus firms to provide express service, too.
Park-and-ride. The DPW plans to add 10 new sites with 1,500 parking spaces to its current 13 park-and-ride lots with 1,600 spaces along the South Shore.
Ride sharing. Caravan for Commuters Inc. is under contract to coordinate means of sharing rides, from carpools to company plans, along the South Shore during the next two years. It's telephone hot line is 227-POOL.
Commuter transportation. Additional commuter-boat service will be provided, and an extension of commuter rail lines southward is being sought.
Signs are being placed on the expressway to note construction, alternate routes, and park-and-ride lots. And, says Tierney, ''We are planning conferences to discuss such ideas as flexible time for office hours and company planned driving pools to and from work for employees.''
Special services such as MBTA police and state police will be expanded. Round-the-clock towing services, bicycle storage, and media information will be provided.
For commuters who stick it out on the expressway, the two center lanes will be reversible, going north during the morning rush hours and south during the evening rush period. During nonrush hours three lanes will be open in each direction. This means no breakdown lanes during these hours. Currently the fourth lanes are breakdown lanes during normal hours. Commissioner Tierney says the northbound section of the highway will be completed during 1984, the southbound half will be completed in 1985.