It used to be that if you wanted to see a roundabout, you had to take a transatlantic flight to a country like Britain or France, where it seems you can’t drive a mile (or a kilometer) without encountering one.
That’s no longer the case. Since the late 1990s, roundabouts have experienced rapid growth in the U.S., with an estimated 7,100 of them now spread across the country.
What’s driving the change?
In a word: safety. Research has shown that roundabouts and other types of “circular intersections” can dramatically reduce motor vehicle crashes. According to the Federal Highway Administration (FHWA), they can reduce traffic-related injuries and deaths by 72-82% compared to traditional signalized intersections.
There are other benefits, too. Roundabouts can handle more “throughput,” meaning more vehicles can pass through them, easing congestion and increasing capacity. Plus, they eliminate hardware, maintenance, and utility costs, making them much cheaper than signalized intersections over the long-term.
Are they safe for pedestrians?
It depends on the type of circular intersection, and what kinds of pedestrian infrastructure is in place. While “roundabout” is often used as a blanket term to describe all road features that require traffic to move around a center island, not all circular intersections can be characterized as roundabouts.
- Rotaries are generally large in diameter (sometimes more than 300 ft.) with high speed limits (30 mph+) and multiple lanes. They were popular before the 1960s, and often lack the bicycle- and pedestrian-friendly enhancements seen on more modern roundabouts. [source]
- Neighborhood traffic circles are typically used at the intersection of two local residential streets for the purpose of traffic calming or aesthetic appeal. Occasionally, they include marked crosswalks, but more often they are unmarked. [source]
- Modern roundabouts employ specific design features to control speed, efficiently move traffic, and accommodate multimodal transportation (e.g. “splitter islands” that channelize traffic and give pedestrians a safe place to rest mid-crossing). [source]
Circular intersections may offer some safety advantages to pedestrians—for instance, they require pedestrians to negotiate only one direction of vehicle traffic at a time—however, there is virtually no data showing they are any safer or better for pedestrians than a standard signalized intersection.
Safety for all road users
Even if on their own, circular intersections aren’t beneficial to pedestrians, it doesn’t mean they can’t be enhanced to provide increased safety. Higher capacity roundabouts with fast speeds in particular can benefit from treatments designed for pedestrians, including those with disabilities.
For example, rectangular rapid-flashing beacons (RRFBs) can be installed at the either end of each crosswalk (as well as on the splitter island) to increase driver awareness of pedestrians on or near the roadway. RRFBs are included in the FHWA’s Spectacular Seven crosswalk safety countermeasures, and have shown significant improvements to yielding rates and safety.
Additional treatments such as raised crosswalks, high-visibility pavement markings, overhead lighting, and advance warning signage can also be used on their own or in conjunction with RRFBs to improve pedestrian safety. And to accommodate pedestrians with disabilities and comply with ADA requirements, curb ramps, detectable warnings, and audible pushbuttons should always be considered.