Petaluma drivers can anticipate more downtown traffic congestion this month as the city picks up where it left off on the Petaluma Boulevard South "Road Diet" project.

The project consists of reducing the number of lanes between East Washington Street to just south of D Street from four to two and adding in a middle turn lane, in an effort to widen lanes and street parking, thereby creating safer conditions for bicyclists and pedestrians.

The good news: City staff says the project should only take about six more weeks to finish and that it won't interfere with the upcoming American Graffiti festivities, set to take place during the week of May 13-18.

City staff has also scheduled the work so as not to coincide with other traffic projects.

"We were really careful to hold off starting the project until the SMART (Sonoma Marina Area Rail Transit) work on Lakeville Street was complete, and to make sure we halted work during American Graffiti," said City Engineer Larry Zimmer. "We want to minimize disruption downtown during this final stage of the project."

Last fall, the city decided to break the work on the road diet into two segments, one before the holiday shopping season and one after. That decision came after the project, which was originally slated to be finished by October, fell behind schedule. As the holiday shopping season neared, the city heard concerns from downtown merchants that the construction would deter shoppers, so officials decided to postpone the rest of the work until the spring.

Now the project is set to begin again.

According to City Engineer Erica Ahmann Smithies, who met with project contractors this week, work will begin on May 6, when workers will install new traffic signal poles at Western and B streets.

Then, work will stop from May 13 through 18, to allow for the American Graffiti activities to proceed without traffic delays.

Work will begin again on May 20 and will involve upgrading lighted crosswalks, signals and ramps in the area, Ahmann Smithies said. Finally, beginning May 28, pavement repairs will begin.

"There will be single lane closures at times, but there will always be at least a single lane open in each direction on Petaluma Boulevard South," she added.

Zimmer added that there will be some minor remaining work to be done during the first two weeks of June, from East Washington to D streets.

He pointed out that the work begin done on Petaluma Boulevard South doesn't involve laying new pavement, but rather the simpler process of "resurfacing" the pavement, which entails laying down a combination of a thick mixture of emulsified asphalt and polymore sealant. "We're treating the pavement that's already out there to lengthen the life of the pavement and adequately cover up the previous lane markers," said Zimmer, who added that it will probably extend the life of the pavement for up to 10 years.

"And during the work, downtown businesses will remain open, so we're trying not to disrupt activities in the downtown area too much," Zimmer added.

City staff said that because traffic signals were originally hung over a four-lane road, which is now being reduced to two lanes, the signals will no longer be lined up appropriately over the lanes. Those signals will need to be realigned. Zimmer said that while work is underway on the traffic signals, certain signals that haven't been moved or properly timed and synchronized will be covered with bags to minimize distractions.