Petaluma's controversial "road diet" along the main drag through downtown may be extended farther south.

At Monday's meeting, City Council members are set to consider whether to seek as much as $3.1 million in grant money to fund what would be a third section of shrinkage along Petaluma Boulevard.

Despite the concerns of some business owners along the street, particularly through the historic downtown segment, the council gave the go-ahead to two construction projects that have reduced the number of traffic lanes but widened the remaining lanes and adjacent parallel-parking lanes.

The "road diet" reduced the main thoroughfare from two lanes in each direction to one lane in each direction with a continuous turn-lane in between, serving both directions. The section of Petaluma Boulevard north of Washington Street was completed first and the downtown stretch between Washington and D Street is under construction now.

Council members now will consider seeking grant money to reconfigure the section from D Street to McNear Avenue.

Project Manager Larry Zimmer said the road arguably needs repaving more than a wholesale reconfiguration, but because the narrow traffic lanes no longer meet federal standards, the road cannot just be repaved without upgrades.

Petaluma Boulevard is one of four streets in the city — along with D Street, Lakeville and Washington — that are eligible for federal road funds. And these federal grants, part of the One Bay Area Grant program, must be used in a "priority development area," which includes Petaluma Boulevard.

About $23 million of the $320 million total available could be allocated in Sonoma County. The funding is competitive, not just parceled out to each jurisdiction, so satisfying the grant criteria is important, Zimmer said.

"This project had it all," Zimmer said. "Having a project that meets all the points gives us the best opportunity to get largest amount of money."

The reconfiguration would replace the current four 10-foot lanes and two 6-foot parking lanes on either side with three 12-foot traffic lanes — one that would be a center turn lane — and two 8-foot parking lanes.

That leaves more space for parallel parking and bicycles, and cuts down the distance in which crossing pedestrians are vulnerable to cars.

The wider traffic lanes also reduce side-swipe accidents, which are common in the narrow downtown stretch, and allow through traffic to continue without delay because turning vehicles will use the center lane.

But council approval of the road-diet plan is far from guaranteed, Zimmer acknowledged. Funding for the downtown section passed with a 4-3 vote, with David Glass, Chris Albertson, Teresa Barrett and Tiffany Renee voting for it.

Albertson said he supports continuing the road diet through to McNear Avenue.

"If the road diet is not going to be an issue for the historic downtown and the business area, I'm in favor of doing it if we can get the road itself paved," he said. "Just to make it two lanes instead of four is not as important to me unless in so doing it we can repave that entire road."

The city would be responsible for matching about $420,000 of the project's $3.1 million cost, Zimmer said.

If the council rejects the road diet plan, Zimmer said the city could apply for $2 million in grants to fund other smaller repaving projects.