ATTLEBORO - South Coast officials said Thursday a proposal to improve bus service to Boston falls short of their desire for their own commuter rail line.

State transportation officials excited Attleboro area officials this week by saying they were considering improved bus service as an alternative to a new commuter rail line from the South Coast through Attleboro and Norton to Boston.

Attleboro area officials said buses would be much less expensive at a time when the state is in dire financial shape. Building a new rail line would not only cost an estimated $1.5 billion, but would cut the city of Taunton in half and cut close to residential areas in Norton and Attleboro.

A new rail line would create dangerous and disruptive grade crossings on 15 Taunton roads and five streets in Norton, they said.

State Rep. Jay Barrows, R-Mansfield, said the bus option was the best idea he heard at a hearing Monday on the transportation options. "Buses are the way to go," he said.

Barrows said buses would cost a fraction of the price tag of a new rail line, would not cause environmental problems and can be accomplished quickly.

But Fall River Mayor Robert Correia said the bus option is not a serious idea.

Route 24 is a "parking lot" because it is already too congested and cannot handle more buses.

Traffic congestion is a major obstacle to economic development in the area and independent studies have found that rail transportation is the only way to address it, he said.

People who advocate for buses should come to Fall River and try to drive to Boston, he said.

"They aren't putting themselves in our place," he said.

State Sen. Joan Menard, D-Fall River, said the South Coast area would only accept buses as a temporary measure until commuter rail service can be instituted.

"My sense is they would not be satisfied with that," she said of the bus option.

Roy Nascinmento, president of the New Bedford Area Chamber of Commerce, said the area really wants commuter rail service and believes it would be an economic boost to the area that buses cannot provide. He said trains have helped cities like Attleboro and would connect South Coast residents with jobs in Boston.

Nascinmento said he has not looked closely at the bus option, but suspects it would not be the economic stimulus that trains would be.

Menard said there is already bus service in the area and the ride to Boston is too long because of congestion on Route 24.

The state Executive Office of Transportation and Public Works, however, is considering an idea that involves creating a "zipper lane" on Route 24 just for buses and other vehicles with multiple passengers.

Zipper lanes are created by have portable barriers erected so one lane of traffic on the opposite side of a highway is dedicated for "high occupancy" vehicles during rush hour.

The Southeast Expressway between Quincy and Boston already has a zipper lane.

When traffic is headed toward Boston in the morning, an outbound lane is dedicated for high occupancy vehicles.

In the afternoon, the barriers are moved so an inbound lane is dedicated.

But, Correia called the zipper lane idea "pie in the sky."

The estimated cost of creating zipper lanes and enhancing bus service from New Bedford and Fall River to Boston is $300 million.

Commuting time by bus would be about 61 minutes under the system.

The cost of creating a commuter rail line through Taunton, Norton and Attleboro is estimated at $1.5 billion. Electric trains would be $1.8 billion.

Commuting time by way of Attleboro by train would be 74 minutes, or 55 minutes by electric train.

A major drawback to the bus option is that it would not attract the ridership commuter rail would draw, transportation officials said. In fact, buses would get the lowest ridership of all the options under consideration.

Menard said the Fall River area has been promised commuter rail for more than 15 years.

She said she understands the concerns of the Attleboro area and agrees the trains should go another way.

The last time an environmental study was done on the train options, it was recommended that the best route would be through Stoughton - not Attleboro and Norton, she said.

Menard said she suspects a new study being done will come up with the same recommendation.

The Stoughton line would also cost $1.5 billion to build, or $1.9 billion if the line is electrified, according to the MBTA.