Breaking News
More () »

Why are more roundabouts being put in across California's roadways?

Love them or hate them, roundabouts are being used more and more for intersections and ABC10 wanted to know why.

SACRAMENTO COUNTY, Calif. — Roundabouts: They're just a circle, but people seem to have a lot of opinions about them.

For many, the classic scene from National Lampoon's European Vacation comes to mind. For others, roundabouts and Europe go hand-in-hand in their mind.

Like them or not, roundabouts are being used more and more for intersections and we wanted to know why.

"Every time you have two roadways that intersect each other, you need to have some type of traffic control," said Roseville Public Works Director, Jason Shykowski.

Traffic engineers and designers, like Shykowski, used to have two main options for intersections: a stop sign or a stop light... until a new idea was brought from overseas.

"Roundabouts were invented around 1970 or so in the United Kingdom," said Alan Glen, an experienced highway engineering expert who currently works for the infrastructure consulting firm, AECOM.

Over the next 20 years, roundabouts popped up across the United Kingdom, Australia and Europe, but the idea wasn't welcomed with open arms when they came to the United States in the 90s.

"There was initially a little bit of reluctance here in the US," said Glen.

For the last 40 years, Glen has specialized in roadway design, serving on national committees establishing the standards of how highways are laid out and playing a key role here in California, especially when it comes to roundabouts.

"I actually was in charge of statewide design standards at Caltrans at the time the Brits were pushing them here on the U.S.," said Glen.

When he and others finally gave the green light to roundabouts...

"It's probably become one of the most effective tools in our toolbox because there's now hundreds of thousands of these across the U.S.," said Glen.

The benefits of roundabouts have proven overwhelming since coming to the United States.

For a normal intersection with a signal, there's 32 points where vehicles can cross the paths of one another, or what experts call "points of conflict."

"In a roundabout, there's only eight of those 32 that remain," Glen explained. "It eliminates all right angle and left turn conflicts."

Credit: Alan Glen, AECOM

When entering a roundabout, the driver is also forced to slow down to follow the circular path. It's why statistics show, compared to stop signs and lights, roundabouts are way more safe.

"We've seen in the U.S., over the last 20 to 30 years, a 90% reduction in fatalities," said Glen. "A 75% reduction in injuries, 35% reduction in overall crashes and a 50% reduction in crashes involving pedestrians."

So, ABC10 put these stats to the test right here in Sacramento. Throughout midtown there's a number of what many refer to as roundabouts, even though Glen explained they are technically traffic circles (roundabouts require yield control).

ABC10 filed a public records request with the Sacramento Police Department asking for the number of accidents that've occurred within four years on G and 25th Street with a roundabout/traffic circle — as well as a block away on G and 24th Street with a stop sign.

Our test proved true. According to Sacramento police, there were five collisions on the intersection with a stop sign while zero at the intersection just a block away with the roundabout/traffic circle.

So, why not replace all intersections with roundabouts?

"Roundabouts are not the ideal tool for every intersection," explained Shykowski. "They require a larger footprint because they take more space."

A 2021 study from U-Haul found Roseville was one of the fastest growing cities in the nation. As the city's public works director, Shykowski has had to keep up with developing the city and its roads.

RELATED: Rockin nears 'build out' capacity as Bay Area residents migrate to the region

"One of our first roundabouts was at the Galleria Mall," recalled Shykowski. "Then we put in a few at a time."

As of April 2023, the city of Roseville has about 20 roundabouts with more coming.

"We're building another one down the street near the fairgrounds right now," said Shykowski.

Besides of the space required for roundabouts, he said they can also cost a pretty penny for cities like Roseville.

"Our most recent roundabout, the cost all-in for design and construction, was over $7 million," said Shykowski. "(A) traffic signal would probably run you about $500,000."

Skykowski said the cost to build in new areas, like housing developments, is not as high.

"We can't afford to put in a $7 million roundabout at all 200 traffic signals in the city of Roseville. That's a lot of money," said Shykowski. "It's a balancing act. You look at the intersections with the worst accidents and see if you can do something like put a roundabout in."

Down in Elk Grove, Glen is working on a project connecting Interstate-5 with State Route 99 and Highway 50 through Grant Line Road.

Credit: Alan Glen, AECOM

"But it does go through the community of Sheldon," said Glen.

His responsibility is to preserve Sheldon while making room for much more traffic. When completed, the project and roadway will divert traffic away from downtown Sacramento.

"We evaluated one set of alternatives with signals and one set with roundabouts," Glen said in reference to a 2.7-mile stretch from Bond Road to Calvin Road in the Sheldon area. "At the end of the process, the (Elk Grove) city council did elect to prefer the roundabout solution."

As for other traffic tools that could become used more and more like we've seen with roundabouts, Glen believes a new configuration is gaining popularity with highway engineers like himself.

"One relatively new configuration is what we call a 'diverging diamond,'" said Glen. "That is a very promising tool."

Glen said the diverging diamond concept reverses the flow of traffic and eliminates the need to turn left across traffic, and he's right about this tool being up and coming. California's first diverging diamond was debuted in Manteca in 2020.

So, even if you don't like roundabouts, you may want to get used to them.

WATCH MORE ON ABC10: Northern California growing into 'mega-region' as people moving from the Bay to Sacramento doubles

Before You Leave, Check This Out