The state has begun installing the new all-electronic tolling system, which will replace toll plazas and the work done by hundreds of toll collectors on the Massachusetts Turnpike by October.

The first gantry to hold the equipment, an overhead bridge-like framework that spans all lanes of the highway in both directions, was installed over the Pike near the Weston/Route 128 interchange earlier this month. The second is due to go up in Southboro, between exits 11 and 11A in February. Sixteen overhead gantries will replace the existing 24 toll plazas. In addition to Southboro, two others will be installed in Worcester County: in Warren between exits 8 and 9 in late April, and in Charlton between exits 9 and 10 in early May. The toll amount will be based on distance traveled as opposed to the number of exits.

The structures will have cameras that scan E-ZPass transponders to take tolls from the motorists. If vehicles do not have a transponder, which are provided free, the gantry camera will record the license plate, and an invoice is mailed to the address of the vehicle's registered owner. Motorists without E-ZPass transponders will incur a surcharge, which has not yet been determined. Seventy-five percent of the 214 million annual transactions that generate $375 million in gross revenue are paid by electronic toll collection.

State law states that tolls are to be eliminated on the western part of the Pike, from the New York border to Route 128, once all the notes and bonds are paid off and the roadway is deemed in good condition. Bonds for the western portion of the Pike, which was constructed in the 1950s, are expected to be paid by January 2017. But the roadway is not considered to be in good condition and would require $135 million annually over the next 20 years for recommended repairs and maintenance.

State officials at a Jan. 7 meeting in Worcester said they will likely recommend that the tolls stay in place after January 2017, but that they be frozen until the next "state of good repair" review, which is conducted every three years by an independent inspection team. Tolls were eliminated from a portion of that section of the pike between Sturbridge and Springfield in 1996. They were restored by the Legislature in October 2013.

After discussions that began in 2010, MassDOT in July 2014 awarded the $130 million gantry construction contract to Raytheon. The system has been tested on the Tobin Bridge since 2014. The Customer Service Center contract for about $204 million was awarded to TransCore, the current E-ZPass contractor.

The contract to demolish and reconfigure the existing toll plazas, estimated at up to $130 million, has not yet been awarded. Some of the costs will come from incoming toll revenues and reserves. A portion will be paid through 10 annual installments.

The new system will generate maintenance and operation cost savings, but that is not the primary reason it is being implemented.

MassDOT's Highway Administrator Thomas J. Tinlin said the main reason is customer convenience and safety, and congestion and emission-reduction benefits.

"I think that people get hung up on the money. Cost associated with tolling will go down. But the real impetus of this program is to increase safety, reduce congestion and increase air quality," Mr. Tinlin said.

He said studies have shown that the rate of rear-end accidents at toll plazas is higher than anywhere else on the highway system because of the interruption of the flow of high-speed traffic.

Another benefit is elimination of congestion at the plazas, providing drivers more than 800 hours of vehicle-delay savings each day, according to MassDOT documents.

Vehicle owners will also save between 500 and 2,500 gallons of gas each day, which will reduce greenhouse gas emissions by up to 7,800 tons per year, according to information provided by MassDOT.

"Anytime you can avoid people stepping on the brakes, causing more emissions, is a good thing," said Mr. Tinlin. "... I think anything we can do to enhance the customer experience is a good thing."

Mary-Ellen Blunt, transportation program manager for Central Massachusetts Regional Planning Commission, said the AET system will have a positive benefit for the region.

In addition to the improvement in safety and reduction in congestion at toll plazas, the extra ramping needed for toll plazas will also be eliminated.

“Generally, toll plazas require a larger footprint than ramps that don’t have toll plazas, so we’ll see less infrastructure and more green space,” she said.

The state will conduct a public review process this spring to determine how tolls will be set for passing under each gantry, the surcharge that pay-by-plate users will incur, and the recommended two-way tolls in the Logan Airport tunnels. Currently drivers are charged one toll leaving the airport. A tollpayer advocate will be appointed to take part in the discussions.

Mr. Tinlin said the state is taking efforts to minimize the impact on the more than 400 toll collectors who will lose their jobs. Up to 200 who work through the end of manual toll collection will be eligible for an enhanced retirement benefit. Some have benefited from training programs to move into other areas of the agency, such as roadway maintenance work or capital projects. Others have been trained to receive their commercial driver’s licenses.

"The training isn’t just to make them more marketable here, but to the outside world as well," said Mr. Tinlin. "We're also working with the state to finance training other than transportation."

Anyone who does not take advantage of those programs will be laid off.