Converting Two East Palo Alto Temporary Traffic Circles to Mini Roundabouts
On October 10, 2022, the City of East Palo Alto installed two temporary traffic circles "at two intersections of concern in the City that are also nearby schools" (Source). The locations are at:
- Pulgas Avenue and Runnymede Street
- Pulgas Avenue and Beech Street
The temporary traffic circles were the demonstration project from the findings of the San Mateo County Office of Education (SMCOE) School Travel Fellowship Program 2021. I was not involved in that year's project, but I read through the team's presentation and learned that the primary motivation for installing temporary traffic circles was to calm traffic on Pulgas Ave in order to make it safer for students to get to their schools.
This year I am on the EPA School Travel Fellowship team. The City's goal is to have zero vehicle collisions with students walking or biking to school within the next five years. By July 31, 2023, we aim to complete the preliminary design for converting the traffic circles from last year's project to a permanent mini roundabout. If that isn't feasible, our objective is to implement another traffic calming quick build or demonstration project.
Traffic Circle vs Mini Roundabout
A traffic circle is not quite a mini roundabout because it still has stop signs, and does not have other improvements like relocated crosswalks, splitter islands, and an island that can be partially driven over by larger vehicles (e.g. emergency vehicles). The traffic circle can be thought of as a bridge between a four way stop sign and a mini roundabout.
Pulgas and Runnymede
This morning I took these drone photos and videos for our engineers, and I wanted to share them here.
Pulgas and Beech
Here is a drone video I took of current traffic going through the Pulgas and Beech traffic circle.
Benefits of Mini Roundabouts
From the Insurance Institute for Highway Safety Roundabouts webpage, these are some of the benefits when roundabouts replaced stop signs:
- reductions in injury crashes of 72-80 percent
- reductions in all crashes of 35-47 percent
- vehicle delays reduced by 13-23 percent
- proportion of vehicles that stopped reduced by 14-37 percent
- 89 percent average reduction in vehicle delays
- reduce carbon monoxide emissions by 15-45 percent, nitrous oxide emissions by 21-44 percent, carbon dioxide emissions by 23-34 percent, and hydrocarbon emissions by 0-40 percent.
Time Savings
Personally, I am excited about the time savings from converting the four-way stop signs to mini roundabouts. I drive or bike on Pulgas Ave everyday, and it would be great to not have to stop 6 times along the 1.29-mile stretch from Bay Road to East Bayshore Rd (Weeks, Runnymede, Garden, Beech, O'Connor, and Camellia). This is not including the initial stop sign at Pulgas & Bay and the terminating traffic light at Pulgas & East Bayshore. Converting the four-way stop signs (currently temporary traffic circles) at Pulgas & Runnymede and Pulgas & Beech reduces the number of stop signs from 6 to 4, or a 33.3% decrease.
Reducing the number of stops signs helps particularly when there are not many cars on Pulgas Ave, such as when I use Pulgas Ave in the evening around 8 or 9pm when driving home. I would say that of several hundred data points driving or biking at this time, I typically see at most one other car going in my same direction within a few hundred feet of me. Given the lower traffic counts at these times, it would be a lot more efficient to not have to come to a full stop.
Environmental Benefits
I will attempt to quantify some of the environmental benefits of mini roundabouts. During the morning rush hour, Pulgas Ave south of Bay Rd sees around 600 cars during peak-hour (East Palo Alto Mobility Study 2020). If two mini roundabouts are installed and if they reduce the need to come to a full stop for let's say 25% of the cars, this has the potential to save 600 * 2 * 0.25 = 300 complete stops. Not to mention some traffic that is not accounted for which crosses Pulgas Ave along Runnymede or Beech but never drives along Pulgas Ave. That is a sizeable amount of air quality improvement from vehicles not emitting as much due to not accelerating from a complete stop.
Opposition to Mini Roundabouts
I expect that there will be opposition to mini roundabouts, similar to how Palo Alto's "roundabouts spark[ed] outrage" (Palo Alto Daily Post). Over 650 people had signed a petition for reasons including:
- drivers being confused
- losing a parking space
- not wanting change
While it is true that elder drivers are more prone than younger drivers to be confused by mini roundabouts, the Institute for Highway Safety mentions that "the average age of crash-involved drivers did not increase following the installation of roundabouts. This suggests roundabouts don't pose a problem for older drivers." If our community wants to see mini roundabouts, we should make the decision based off of data from previous studies.
Conclusion
From the data I have gathered from studies, the conversion of 4-way stop signs to mini roundabouts in East Palo Alto makes sense. I expect mini roundabouts to reduce collisions, reduce injuries, decrease waiting and stop time, improve the air quality from lowered vehicle emissions, and make it safer for children to walk and bike to school. While the School Travel Fellowship looks at the benefits of mini roundabouts through the lens of a student traveling to school, I am also looking at the benefits of mini roundabouts to East Palo Alto residents. Pulgas Ave is used at least 80% of the time for trip starting or ending in East Palo Alto (recall the Mobility Study earlier that measured 20% cut through traffic during AM hours). These mini roundabouts will largely benefit East Palo Alto residents and make it easier and safer for us to get home.
If you have any thoughts, please comment below or send an email using the contact form.