PORTLAND – Highway officials are considering rerouting vehicles and adding lanes to handle possible summer traffic gridlocks on Interstate 295, the highway beginning in Scarborough and traveling north to Gardiner.

The volume of traffic in the last two decades has more than doubled on certain sections of I-295, according to Maine Department of Transportation officials. Traffic increases could disrupt the normal flow of traffic on the highway.

The transportation department, the Maine Turnpike Authority, and others have begun studying traffic patterns along the highway. They plan to release a report by the end of the year suggesting possible remedies to problem congestion.

Estimates show some sections of I-295 in Portland already struggle to handle traffic during rush hour and project that peak traffic could only get busier. Northbound lanes on I-295 in Falmouth are expected to go from 2,950 vehicles at rush hour in 2002 to 3,219 in 2025, the transportation department estimates.

“There is no question traffic on the interstate has grown substantially. You only have to drive it,” said Greg Nadeau, a transportation spokesman. Nadeau added that the plan is the first step in what could be a five- to 10-year process.

Projects the traffic committee plans to consider include widening the highway from four to six lanes in Portland, which could be done by paving over the grass median separating north- and southbound lanes, said John Duncan of the Portland Area Comprehensive Transportation Study committee, a traffic planning agency.

Another remedy to the congestion would be to reroute traffic onto the Maine Turnpike to prevent drivers from using the interstate as a thruway and requiring an additional lane in each direction that would lead to the turnpike, he said.

Conrad Welzel, planning and governmental affairs manager for the Maine Turnpike Authority, said the idea of rerouting traffic has been discussed before. But this study could help determine what projects, if any, the turnpike and interstate can do together.

Other changes the committee will consider include reworking key exit and entrance ramps, expanding commuter rail service from Portland to Brunswick, and adding a system of electronic signs to alert drivers of traffic conditions.

Some committee members have questioned whether the study will address the increase in traffic without confronting what has caused the increase.

Theo Holtwijk, planning and development director in Brunswick, said the committee needs to look at issues such as urban sprawl and an increased reliance on cars before adding more highway space.

Otherwise, traffic on the interstate will only continue to increase, he said.

“This ought to be a warning signal,” Holtwijk said.