Rainier Avenue is getting a makeover, with construction underway as workers install new underground pipes and upgrade service lines ahead of planned aboveground work, which will ultimately result in a new roundabout and other changes.

As part of an assortment of “utilities, paving and traffic calming upgrades” the city has budgeted for Rainier, construction crews are currently installing a new recycled water main — completed last week — and upgrading water services connecting to Rainier Avenue homes, after which they will begin street-level improvements to repave the road, add protected bike lanes and install a new roundabout at the intersection of Rainier and Maria Drive, according to the project website.

The work will likely mean more traffic slowdowns on Rainier as crews block off parts of the well-used road connecting N. McDowell Boulevard and Sonoma Mountain Parkway. The city has warned of potential traffic delays Mondays through Fridays between 8 a.m. and 5 p.m. for the duration of the construction, and asks drivers to allow for more time when traveling down Rainier Avenue.

The gamut of upgrades is expected to cost a little over $4 million, “which includes all components: underground utility work, road paving, and safety improvements such as the new roundabout, curb ramps, protected bike lanes, and upgraded crosswalks,” the city says. Upgrades to 60 individual water services and installing the new recycled water main is budgeted at slightly more than $1.4 million, while the road paving and safety improvements will cost just over $2.6 million, according to a draft project list under the Sonoma County Transportation Authority’s project plan.The new recycled water main should reduce the city’s dependency on potable water by delivering recycled water for city irrigation, according to the project website.

On Monday, crews began upgrading water service lines direct to homes, which is expected to improve water pressure, according to a notice from Team Ghilotti’s construction crew. Crews will work on the portion between Maria Drive and Sonoma Mountain Parkway first before getting to the section between Maria Drive and N. McDowell Boulevard, according to project manager Nate Luna, who added that the belowground portion of the work should wrap up by Sept. 26.

“While no water shutoff is expected, residents have been notified to prepare for water outages lasting from half an hour to four hours,” Luna said.

The installation of a roundabout, lane reductions and more protected bike lanes on the east side corridor is expected to commence in spring 2026, according to the city’s project page. While drivers can currently park on both sides of Rainier Avenue, once completed, the changes will result in the removal of parking on one side to add buffered bike lanes. Although some residents have questioned the reduction of Rainier Avenue from four lanes to two in order to accommodate the bike lane, “traffic volumes on Rainier Avenue are well below the threshold to support one through lane in each direction,” according to the city’s website.

The roundabout at Maria Drive will be the city’s sixth, with this one designed to resemble the roundabout at Corona Road and Sonoma Mountain Parkway.

All design changes are intended to keep traffic moving and reduce pedestrian crossings from 70 feet to 20 feet, according to the city’s project page.

In 2022 the city installed a pilot project on Rainier Avenue to test reduced driving lanes and a buffered bike lane between N. McDowell Boulevard and Maria Drive. Feedback from that project informed the changes to be seen on the entirety of Rainier Avenue, according to the city’s website.

For more go to cityofpetaluma.org/rainier-active-transportation-improvements-with-paving-project.