All-electronic tolling would be activated on Oct. 28 and is expected to impose higher fees for nearly half the trips by motorists using a Massachusetts-issued E-ZPass, according to a proposal unveiled by state officials Monday.
The new system — in which overhead gantries automatically charge tolls as vehicles pass — would cover the Tobin Bridge, the entire Massachusetts Turnpike, and the Sumner/Callahan and Ted Williams tunnels.
According to the proposal, the cost of driving from Lee to Springfield on the Pike, for instance, would increase from $1.20 to $1.30, officials said. Driving from Westborough to Weston would increase from 70 cents to 95 cents.
On the other hand, drivers traveling all the way from the New York border to downtown Boston would get a break. Under the current system, they pay $6.60 in tolls (excluding charges for the Tobin Bridge and city tunnels). Under the new system, they would pay $6.15.
Overall, for drivers with a Massachusetts-issued E-ZPass, about 47 percent of trips would cost less than they do today and about 5 percent of trips would cost the same, officials said.
The rest would cost more. About 14 percent would increase by about 5 cents, and 20 percent would increase by 10 to 20 cents; the rest would increase by a quarter or more.
Officials said the toll structure had to undergo such a substantial change because the new system will feature just 16 gantries to replace 26 toll plazas.
The gantry locations were determined years ago, said Transportation Secretary Stephanie Pollack. "We had to work with where they are," she said. "We're trying to make it as fair as we can."
State officials say they expect the new system — and the higher rates in some cases — to generate some criticism. They plan to hold a series of hearings on the new tolls in September, before holding a formal vote on the proposal on Oct. 6.
On Monday, Transportation Department board member Joseph Sullivan, the mayor of Braintree, suggested offering an initial grace period under which motorists wouldn't be charged higher rates or additional billing fees for not having transponders.
"Despite our efforts, I do think there is going to be some confusion," said Sullivan. "I think there needs to be sensitivity from us."
State officials also said Monday that the changes — originally projected to save $50 million a year — now will save only $5 million.
The new tolling system will end the need for drivers to stop, or even slow down, to pay tolls. State officials say it will reduce congestion, pollution, accidents at toll plazas, and, they hope, drivers' commute times.
"It's about public safety, it's about air quality, and it's about congestion," said Highway Administrator Thomas J. Tinlin.
"This is such an enormous moment in time for we at the highway division and for the state," he said. "Very rarely are you able to do a project that touches those three things."
Under the new plan, some trips that don't currently include tolls would in the future — and vice versa.
For example, a gantry has been installed in Newton between Interchanges 16 and 17 on the Pike.
Tolls would be also charged in both directions on the Tobin Bridge and in the Boston tunnels under the new plan. But the rates would be divided equally so that a round-trip cost to travel on the Tobin or either of the tunnels would be the same as it is today.
The new toll proposal calls for drivers with E-ZPass transponders issued by the state to pay cheaper rates than drivers with transponders from other states, such as New York or New Hampshire. Massachusetts offers transponders for free.
Drivers without transponders — whose license plate numbers will be captured by gantry cameras so they can be billed by mail — would pay the highest tolls to cover the additional costs the state would incur to process their transactions.
Officials said they project that all-electronic tolling would collectively save drivers more than 280,000 hours and up to 875,000 gallons of gasoline a year, while reducing greenhouse gas emissions by up to 7,800 tons annually.
But the new system has also raised concerns.
Privacy advocates said they are worried by the volume, storage, and use of data the technology collects as drivers pass under the gantries. And the new toll rates are expected to raise questions and, possibly, criticism.
State officials on Monday also outlined plans to raze the old toll plazas. Work to tear the toll plazas down is set to begin as soon as the new system is turned on.
Officials expect the initial phase of demolition may slightly disrupt travel through toll plazas. But officials expect to have enough work done within 30 days to raise speed limits somewhat.
"It's going to be a little choppy in those first 30 days; then it gets better," said Tinlin.
Drivers can expect to see the full benefits of the new tolling system once the toll plazas are torn down and the roadways there rebuilt. That's scheduled to be done by the end of 2017. The board voted Monday to spend up to $132.8 million for that work.
The transition would also end the state's need to employ toll collectors. Officials said 510 part- and full-time employees would be affected, though some would transition to other jobs with the Transportation Department. The department would also offer early retirement incentives for about 312 workers hired before Jan. 31, 2014.
Several years ago, the state had projected it would save about $50 million annually in operating costs. But officials now say those estimates failed to factor in significant amounts of both capital and operating costs, and they expect the potential savings will be much less — only about $5 million a year in operating costs.
Motorists can sign up for a transponder online by clicking here.
A list of RMV, AAA, and customer service center locations where transponders can be picked up in person is available by clicking here.
Matt Rocheleau can be reached at email@example.com. Follow him on Twitter @mrochele.