The Orange County Transportation Authority is working on a second toll-road option for the San Diego (405) Freeway improvement project that would keep the Fairview Road overpass from being torn down.

The option, called Alternative "3-A," would have two toll lanes like Alternative "3," but they would start north of Fairview and south of Harbor Boulevard.

Under that choice, crews would not have to tear down the Fairview bridge that Costa Mesa widened a few years ago, or create a new lane from the Corona del Mar (73) Freeway to the 405.

The project would cost less money — Alternative 3 has a $1.7-billion price tag — but might require more environmental review if the agency recommends 3-A to the California Department of Transportation, said OCTA Chief Executive Will Kempton.

"If we can make this facility have less community impacts, it'll be a better facility," Kempton said.

OCTA staff presented Alternative 3-A to the regional planning and highways committee Monday morning. The committee is a subset of the larger OCTA board.

The committee heard a summary of the public's concerns with OCTA's plan to add lanes to the 405 between the San Gabriel River (605) Freeway and the 73, one of the most congested stretches in Orange County.

OCTA staff estimates that stretch of the 405 will have to deal with an additional 100,000 cars daily by 2040.

Over the last two months, OCTA has seen six city councils — including Costa Mesa's — adopt resolutions opposing Alternative 3, which would add one general-purpose lane and convert the existing carpool lane into a toll road along with constructing a second toll lane.

Five mayors — including Costa Mesa's — and Huntington Beach's mayor pro tem wrote a letter to OCTA and state lawmakers last week endorsing Alternative "2," which adds two general-purpose lanes between the 605 and Euclid Street in Fountain Valley. The carpool lane would remain as is.

More than 1,200 people submitted comments, mostly favoring Alternative 2 as well.

OCTA staff Monday said they got the message loud and clear and have tried to make adjustments to each alternative. Alternative 3-A is an attempt to placate Costa Mesa's concerns about the bridge. Every bridge along the project's path would have to be torn down and rebuilt.

Engineers may modify the project's onramps and offramps to appease Fountain Valley, redesign the additional lanes to limit the impact to business parking in Westminster, and reexamine sound wall placements in Seal Beach.

Costa Mesa resident Jay Humphrey, a former city councilman, suggested engineers rework the Ellis Avenue onramp in Fountain Valley.

He said the current proposal pushes a sound wall close to Costa Mesa homes near Moon Park.

Committee member and Fountain Valley City Councilman Larry Crandall took issue with the suggestion.

If the community had agreed years ago to building a bridge over the Santa Ana River between Gisler Avenue in Costa Mesa and Garfield Avenue in Fountain Valley, then there wouldn't be so much congestion on that onramp, he said.

"Maybe we'll have to reopen that issue," Crandall said. "Pick your poison."

joseph.serna@latimes.com

Twitter: @JosephSerna