Gov. Janet Mills toured the Veranda Street site of the new bridge being installed along Interstate 295 in Portland on Saturday afternoon and said she was pleased with the rapid progress of the project.

“I’m thrilled with the technology, thrilled that it’s going on time and on budget,” Mills said. “Three days’ time, and this bridge will be done. It’s amazing. It’s like giant Legos going together.”

Workers had moved the southbound part of two new prefabricated sections of bridge span into place above the highway by the time Mills arrived on the scene shortly before 5 p.m. The southbound section was to be slowly lowered to connect with the highway Saturday night, according to Maine Department of Transportation spokesman Paul Merrill.

Mills gestured to the houses in the neighborhood and the handful of residents who walked down to the site to watch the construction.

“This project will give these neighbors some extra space,” the governor said, referencing the wholesale redesign of Veranda Street that will accompany the bridge replacement. A confusing and dangerous jumble of highway ramps and one-way travel lanes surrounding the bridge underpass will be replaced with two simple intersections and streets wide enough to accommodate sidewalks and bicycle lanes. Construction on the project is scheduled to finish in November.

Mills also thanked the MaineDOT and Maine contractors Cianbro and Shaw Brothers Construction for their efforts on the massive project.

Merrill said the northbound bridge section was to be moved into place and connected overnight Saturday into Sunday morning. Once the bridge pieces are laid into position, construction crews will spend most of Sunday and Monday morning bulldozing earth for filler and paving the bridge.

Merrill said the project remains on schedule and should finish on time, by or possibly before 11 a.m. Monday, with the busy stretch of highway reopened to traffic.

Construction workers finished demolishing most of the I-295 bridge on Saturday morning as part of an ambitious project to replace the overpass in one weekend.

I-295 is closed just north of Exit 9. Motorists must find detours until late Monday morning.

Spectators gathered throughout the day to watch the trucks, cranes and construction workers. A thin stream of detour traffic was confined to one lane on Veranda Street beneath the bridge. I-295, a heavily traveled four-lane highway that normally takes drivers over the bridge between Portland and Falmouth, is closed in both directions north of Exit 9.

The $20.8 million project, six years in the making, began Friday night when traffic on the highway, which carries 53,000 vehicles a day, was halted at 7 p.m. and demolition of the 60-year-old, structurally deficient bridge began.

People who live in the neighborhood have been watching the project from their sidewalks and backyards.

“I’ve never seen this before,” said Parke Leslie, who lives roughly a mile from the project. “This is a whole new concept here.”

Cianbro, the primary contractor, has 64 hours to complete the work. The Pittsfield firm is working with Shaw Brothers Construction of Gorham, which began tearing the old structure down Friday night.

There are roughly 90 construction workers on site over the weekend, according to Merrill. Most of the workers were from Cianbro and Shaw Brothers.

“It’s a pretty amazing engineering feat,” said Frederick Dobson, a neighborhood resident. Dobson was walking his dog Saturday morning and watched a crane swivel in the distance. He has lived in this neighborhood for 50 years and used to work in construction himself, on power plants.

“They’re really zipping along,” he said.

Steel beams of the old I-295 bridge over Veranda Street in Portland are removed on Saturday morning. Gregory Rec/Staff Photographer

The new bridge, which was already built to be installed, comes in two sections and was in position alongside the highway on Saturday morning. Each part is 80 feet long, 47 feet wide and weighs 400 tons.

Falmouth residents Susan Hall and Jennifer Curran were standing with half a dozen other neighbors Saturday afternoon on one side of a fence separating the construction from the neighborhood. They said they were hoping to see when the first section of the new bridge was lifted into the air.

“It’s so huge to see them do that,” said Hall. It was her third time at the site Saturday.

Across from the spectators was a food truck, run by Fat Guys, which typically serves fair- and festival-goers. On Saturday, Fat Guys was serving meals to dozens of contracted employees on site.

Tara Coffin, project administrator for Cianbro, was helping to staff the kitchen Saturday afternoon.

“We have steak and cheese, sausage, sandwiches, egg salad.” Coffin said. Outside the food truck was a table of snacks. There was a coffee urn on the counter.

During bridge construction this weekend, all through-traffic should detour onto the Maine Turnpike and get back onto I-295 using the Falmouth Spur.

Traffic heading north on I-295 and Route 1 should detour onto the Exit 9 off-ramp heading toward Falmouth. Vehicles can connect back to the highway and communities north via Route 1.

Southbound vehicle traffic should detour to Bucknam Road in Falmouth, then south on Middle Road to Ocean and Washington avenues for a connection to I-295 south.

Staff Writer Peter McGuire contributed to this report.