Bassett & Upham Mini Traffic Circle

A mini traffic circle located at the intersection of Bassett and Upham Streets was installed in March of 2022 to help slow traffic and increase safety for all road users. Since its installation, we have observed a significant reduction in speeding in the area and have received primarily positive feedback from the community. We will now make the traffic circle permanent.

Thank you to everyone who took time to share input with us. We are proud to work closely with our community to make the streets in Petaluma the safest and best they can be.

What Did We Learn?

We learned the traffic circle:

  • Significantly reduced speeding in the area (top speeds reduced from 63 mph to less than 50 mph)
  • The normal speed of traffic in the neighborhood remained the same (26 mph)
  • Enforceable speeding violations were reduced (from 10% down to 4%)

Why Bassett & Upham?

This location was selected due to concerns from local residents regarding traffic speed and the proximity of the location to Petaluma High School, City Hall Park, and St. Vincent’s Church Plaza.

Prior to installation of the mini traffic circle during a week-long observation period of this 25mph zone, City teams surveyed 3000 cars, of which 300 traveled at speeds warranting tickets, with top speeds clocked at up to 63mph. This, coupled with complaints received by City regarding high speeds, and identification of Bassett as a recommended walking route by the Safe Routes to Schools Engineering Evaluation, inspired the City to try out the mini traffic circle demonstration at this location.

The City’s Police and Fire Department have reviewed the project’s design and will be monitoring its performance.

What is a Roundabout or Traffic Circle?

Studies show Roundabouts and Traffic Circles -- a type of circular intersection where road traffic flows in one direction around a central island – are a great way to slow down traffic and improve safety, and are more efficient than conventional intersections.

They promote a continuous flow of traffic and decrease congestion on approaching roads. Modern roundabouts are also designed to be safer for cyclists and pedestrians than conventional intersections because road traffic tends to move at a slower speed (15 to 20 miles per hour) than at intersections with traffic lights or stop signs. Traffic circles are used on lower volume neighborhood streets to calm traffic.

CLICK HERE for a video from Pittsburg, PA demonstrating how mini traffic circles function.


Where are the Four Roundabouts in Petaluma?

There are four roundabouts in Petaluma at South McDowell Blvd., Corona Road, Magnolia Ave. and Ely Road. There is also a mini traffic circle demonstration projects at Bassett and Upham Streets. (Demonstration projects are designed to give the community a chance to experience a proposed change and provide feedback to help us determine if a project is a good fit for a neighborhood.)


What are the Benefits of Roundabouts and Traffic Circles?

Using roundabouts and traffic circles are beneficial because they:

  • Help to calm traffic
  • Result in reduced speeds
  • Eliminate left turns which increase safety because crashes, if they occur, will be at an askew angle not in a “T bone” fashion
  • Require less maintenance
  • Have lower yearly operational costs
  • Reduce greenhouse gas emissions by reducing vehicle idling time
  • Reduce ambient noise associated with a stop condition


Tips for Using a Roundabout or Traffic Circle

Wondering how to safely navigate a traffic circle? Here are some essential tips to remember:

Vehicle Drivers
These rules also apply to motorcycle riders and to bicyclists who choose to ride around the roundabout.

  • Slow down as you approach the roundabout. Always watch for pedestrians in the crosswalks.
  • Yield to traffic in the roundabout. When entering the intersection, always yield to vehicles and cyclists already within the circle. Traffic on the left always has the right of way. Note that drivers may not signal correctly, or at all.
  • Circulate counter-clockwise around the circle. Never turn left into the roundabout.
  • Use your turn signal when you exit. While still in the roundabout, use your turn signal to indicate your exit. This notifies drivers waiting to enter the roundabout when they can safely proceed.

Cyclists and Pedestrians

  • Bicyclists have the same rights as vehicles in a roundabout and must abide by the same rules of the road. Cyclists can either ride through a roundabout with traffic or walk their bicycles through the pedestrian crosswalks.
  • Pedestrians should use the designated crosswalks to navigate around the circle. Before entering the crosswalks, they should look for approaching vehicle traffic.
  • Pedestrians and cyclists must never go to the center island in a roundabout. This is extremely dangerous.

For more information about roundabouts, including research, safety and educational materials, go to:

Traffic Impact

Traffic impacts are expected to be minimal.


Intersection of Bassett and Upham

Project Status/Timeline

Construction is complete.


This project is funded by Traffic Impact Fees and Street Maintenance.

Bid Details


cip bassett and upham
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