City workers on Thursday began removing the much maligned temporary roundabouts on Humboldt Street, replacing them with a series of flat-topped speed bumps aimed at slowing traffic along Santa Rosa's so-called Bicycle Boulevard.

All the elements "associated with the circles are being removed," said city transportation planner Nancy Adams.

The work closes a contentious chapter in the city's efforts to be more bicycle-friendly.

Four temporary traffic circles were installed along a one-mile stretch of Humboldt Street in 2009 as a way to put bicyclists on a more equal footing with cars.

Supporters hoped the project would create a safer, more comfortable riding route for bicyclists that would encourage more people to pedal to and from downtown.

Average traffic speeds did drop, but the circles confused some drivers. The safety of pedestrians at intersections where traffic did not stop also became an issue. Some residents also resented their street being used as what they saw as a social experiment.

Challengers for city council last year cited the project as evidence of the skewed priorities of the previous environmental-leaning majority. Making the circles and other improvements permanent was estimated to cost as much as $800,000.

Last fall, the council's most ardent bicycle advocate, Veronica Jacobi, lost her reelection bid and a majority viewed as more favorable to business interests returned to power. One of the new council's first moves was to remove the traffic circles. The installation of speed tables was a compromise aimed at finding a different way of reducing traffic speeds.

Adams said the project has been a "sensitive" one for the neighborhood, which was about evenly split over whether to keep the roundabouts or scrap them.

"It's been a very challenging effort to try to implement something that wasn't really well defined in folks' minds, in a neighborhood that's very large and diverse and has a lot of different ideas," Adams said.

Work to remove the four circles and replace them with six mid-block speed tables will take about two weeks, she said.

The intersection at McConnell will return to a four-way stop, while the three others will have stop signs reinstalled only in the east-west directions, letting north-south traffic flow unimpeded.

Signs referring to the street as Bicycle Boulevard will remain.