Petaluma may soon get a bicycle boulevard on East D Street that includes efforts to manage traffic and reduce emissions, but the plan has some neighbors worried that proposed traffic circles will have unsafe effects on traffic flows in their neighborhood.

The bike route, in preliminary design stages at the city's Public Works department, is designed to help curb greenhouse gas emissions and allow for safer bike access across town. The "pilot" project is made possible by a $50,000 grant from the Bay Area Air Quality Management District that is set aside for emissions reduction.

Many of the design details are still being worked out, but plans center on traffic calming measures in the three intersections on East D street between Payran Street and Lakeville Street. The route will be similar to the five-block-long Humboldt Street Bicycle Boulevard in Santa Rosa, said Lynne March, a planner with the Sonoma County Transportation Authority, which distributed the grant.

Whatever design is decided upon will be part of a one-year pilot period while city officials monitor the plan's effectiveness.

"Whatever we put up will be temporary," said Curt Bates, an engineer with the city's Public Works department. The project will likely include "barriers for traffic circles and signage to let people know that this is a bike boulevard," he said.

Plans for an East D Street bike boulevard were part of the General Plan adopted in 2008, and have been approved by the city's Bike and Pedestrian Advisory Committee.

One of the main goals of the project is "to give bikers and alternative to East Washington Street," said Bates. East Washington Street, one of the main routes across town, is dangerous for cyclists because of the speed and amount of traffic, he said.

City officials say adding traffic circles and markings will help slow traffic and make it easier for cyclists and cars to share the road. As well, traffic circles reduce idling time and prevent lines of cars from forming. Other traffic calming measures could include road markings and striping, signage, curb "bulb-outs," and more.

Most of neighbors' concerns center on the traffic circles and the removal of stop signs at intersections.

"If we didn't have stop signs here, it would end in tragedy; I'm convinced," said Annie Van Maaren, who owns EverMay Garden Center on the corner of East D and Wilson streets. "Is the death of one pedestrian worth the carbon emission reduction?"

Van Maaren said that she is concerned that traffic circles would prevent large trucks from navigating the street and making deliveries at her store, hurting her business.

"I seriously don't see how a roundabout, however small, will work," she said.

Van Maaren said she is also worried that the removal of stop signs could increase traffic flow, rather than slow it, and that additional road markings could reduce the amount of parking spaces.

"Even with the stop signs, it can be a very dangerous street," she said.

"On paper, it looks different than in reality," she said.

Bates said that whatever plan is ultimately decided on will not harm businesses or block deliveries. If certain aspects of the design are found to not work well after the pilot period, they can be removed or modified, he said.