The Massachusetts Turnpike tollbooths are gone, replaced by an automated system of electronic gantries that lets drivers pay without slowing down. But their successors — dirt-filled construction zones — aren’t going anywhere fast.

More than six months after the gantries made their debut, some drivers are wondering when the $132.8 million demolition project will be finished and the Turnpike will finally be free of construction equipment.

“They knocked down the tollbooths in about an hour and a half,’’ said Larry Cetrulo, who takes the Pike from Cambridge to Boston’s Seaport District and says he sometimes sees no one working in the construction zones. “And now, for the next seven months, there’s [going to be] a pile of rubble narrowing these lanes.’’

Transportation officials say they made it clear from the outset that the demolition and construction would be done by the end of the year, and have marked Oct. 27 as the scheduled completion date.

Patrick Marvin, a spokesman for the state’s Department of Transportation, said project contractors have met all their construction milestones so far, and that workers aren’t usually at the sites during rush hour by design — they don’t want the project to interfere with traffic.

“MassDOT’s goal is to conduct scheduled activities in a manner which is safe and has the least impact on the traveling public,’’ Marvin wrote in an e-mail.

In some cases, work has proceeded ahead of schedule. Two contractors, SPS New England and DW White, have received about $1 million in bonuses for their progress in the highway district that included the Weston and Allston-Brighton toll plazas.

The project had been halted on some days because of weather, since heavy snow, rain, and wind could create unsafe conditions or prevent workers from paving, Marvin said. The state doesn’t track those days, he said.

“MassDOT monitors progress but does not see a need to scrutinize hours as long as the contractors are abiding by all the terms of the contract,’’ Marvin said. While construction sites may appear empty, employees are sometimes working on drainage and electrical issues that may not be obvious to passing drivers, he said.

As work along the Turnpike moves forward, the final tollbooths — at the entrance to the Sumner Tunnel — are finally coming down. The state transportation department plans to demolish the plaza Friday through Sunday. It will require some overnight closures of the tunnel, and the structures will be gone by May 8, officials said.

The delay occurred when highway officials presented a design for the new entrance in early 2016. Some East Boston residents were not pleased.

Michael Passariello, a Boston Latin Academy senior and youth activist with Neighborhood of Affordable Housing, an East Boston-based community group, said the original design encouraged drivers to speed under the gantries and into the tunnel, even though the roadway would run alongside an entrance to the East Boston neighborhood.

“Altogether, it was a traffic and safety nightmare,’’ he said.

Thomas Tinlin, the state’s highway administrator, acknowledged that the original design was too “highway-centric,’’ particularly so close to a thickly settled neighborhood.

The new design includes more space for greenery, and traffic islands that help separate vehicles bound for the tunnel from others heading toward East Boston.

In recent months, state Representative Adrian Madaro, a Democrat from East Boston, led public discussions over the new design.

The move to all-electronic tolling is considered a major step toward reducing traffic and environmental impacts and improving road safety, since drivers will no longer have to slow down at the plazas.

The state has paid $130 million to Raytheon to build and maintain the gantries, more than $200 million to TransCore for billing services and customer service centers, and up to $132.8 million for the demolition process to various contractors.

When the transition to gantries began in late October, transportation officials warned that traffic would likely be terrible as long as demolition crews were on the road. They urged drivers to avoid rush hour if possible. Many took that advice, and with crews working around the clock, the transition to gantries went smoothly.

So smoothly, in fact, that commuters are wondering why the rest of the project seems to be dragging on so long.

“I remember people saying they’re going to do this quickly and expeditiously, and now, you never see anyone working on them,’’ Cetrulo said.

Nicole Dungca can be reached at nicole.dungca@globe.com. Follow her on Twitter @ndungca. Follow her on Facebook at www.facebook.com/startsandstops.