The orange construction barrels that became a permanent part of the Interstate 295 landscape were removed last week, signaling the end to a $22.4 million highway improvement project that began six months ago.

But commuters shouldn’t get too comfortable.

The Maine Department of Transportation says it will return next spring to start bridge repair work and to pave the section of Interstate 295 located south of Tukeys Bridge.

“We really want to express our thanks to area businesses and motorists for their patience during this important project,” David Sherlock, the DOT’s bridge program manager, said in a statement. “We realize that ongoing construction activity was difficult at times but we made significant strides in improving one of Maine’s busiest highways.”

Over the course of the project, an estimated 18 million cars and trucks traveled through the work zones, the state said.

“Despite our best efforts, traffic congestion did result on occasion from delays caused by minor accidents,” Sherlock said. “This does highlight the importance of safe driving, and we’re very appreciative of those motorists who obeyed reduced speed limits and drove cautiously through our work zones.”

Most of the work took place at night between the hours of 7 p.m. and 6 a.m. in an effort to minimize the impact on motorists.

Motorists who used the highway at night would often encounter glaring light towers that illuminated the construction area. Those are gone now.

In total, crews paved 40 miles of highway between Scarborough and Brunswick, paved 36 miles of on- and off-ramps, completed repairs to 29 bridges and overpasses, and repaired all eight lanes of Tukeys Bridge.

Crews also installed 14 miles of new guardrail, mostly on the interstate north of Portland.

Ted Talbot, MDOT spokesman, said next year’s project, which has not been put out to bid yet, will shift the highway improvement focus to the northbound side of 12 bridges that intersect with Interstate 295. All of those bridges are located south of Tukeys Bridge.

Talbot said the southernmost affected bridge will be the Maine Turnpike approach road in Scarborough.

Other bridges due for repairs include the Fore River bridge that connects South Portland with Portland, the Congress Street overpass, the bridge over Forest Avenue, and the bridge over Franklin Street.

Sherlock said his staff is still developing a traffic control plan for the 2012 improvement project but he added, “It’s going to be as challenging as Tukeys Bridge, especially in the Congress Street off-ramp area.”

Sherlock said the project, which could cost in the vicinity of $8 million, could start as soon as April.

“We are getting there (toward the end of improvements). After all, it is the busiest corridor in the state,” Sherlock said.

In 2013, Sherlock said, crews are scheduled to pave the northbound lanes of Interstate 295 south of Tukeys Bridge.

“That should be relatively pain free with most of the work being done at night,” he said.