Roundabouts

Roundabouts: Safety & Emergencies

Roundabouts are safer for cars than signalized intersections.

It depends on circumstances.

There are many careful studies to support this: see references here and a thorough study in The Netherlands. Safety for automobiles is probably the strongest reason to consider roundabouts. One of the better popular press articles I've found is at autos.aol.com. However, this is not a guaranty for all roundabouts. In the Albany, NY area, "Crashes increased at 15 of the 20 roundabouts built where a previous intersection existed..." (Albany Times Union, June 27, 2011). Safety benefits of two-lane roundabouts vary widely, and this type of roundabout can actually increase accident rates compared with signalized intersections.

So, in specific cases, "safer" might mean a lot or a little, depending upon

How severe is the safety problem initially?
How successful is the roundabout design/installation?

It's quite plausible that if you roundabout-ize your worst signalized intersections, significant improvement will occur. What happens if you replace a very good 4-lane (+ turn lanes) intersection [such as we have on Trinity] and make it into a roundabout? Is there relevant evidence?

Some mixed results seem to be accumulating. The dailygazette.com of Schenectedy, NY reports "Accidents are up on a stretch of Route 67 where five roundabouts were built two years ago, but injuries are not, according to state Department of Transportation statistics". (Unfortunately, one must subscribe to see the article.)

Fatalities involving only cars can be found, as well. Here's an example from Birmingham (UK). As usual, lack of details about the roundabout make it difficult to see how the situation compares to other intersections. (I think lack of detailed, systematic reporting affects interpretation of all kinds of accidents.)

Two-lane roundabouts, discussed on the next page, present more serious hazards.

[If roundabouts are implemented in Los Alamos, it is worth some serious thinking about the hazards represent by trees and bronze sculptures in the central island. Aside from the danger of hitting them, greater sight distance is supposed to be an advantage of roundabouts-- what happens if that is restricted by overzealous landscaping?]

I didn't realize it until recently (March, 2016), but the 2011 Albany Times-Union article discussing the poor accident record in their 2-year-old string of roundabouts shows an incredible level of hubris among the DOT persons responsible for their operation. Here is the passage that I consider very telling.

Aggressive drivers are speeding through rotaries and failing to yield the right of way, said Mark Kennedy, director of traffic and safety for the state Department of Transportation in the Capital Region.

"We have found that single-lane roundabouts definitely reduce accidents," he said, referring to the state rotaries. "With multi-lane roundabouts, some are better, some are worse. There are two that are somewhat problematic."

...

The accidents are not slowing down the construction of roundabouts in the Capital Region. There are two more, both with double lanes, under construction in Malta and another being built in East Greenbush.

"We've learned quite a lot about the design and operation of roundabouts" over the past five years, said James Boni, assistant to the state DOT's regional director. "If we were to design these problematic roundabouts today, we would have designed them quite a bit differently."

In reviewing crash data, DOT officials said they learned the accidents are not being caused by older people or those from outside the area.

"The accidents tend to be experienced drivers between 25 and 50 with a local zip code," Kennedy said. "It tells us that people familiar with the roundabouts and where they want to go, they are driving too fast. They are also choosing to be in the wrong lane."

To fully reduce crashes, drivers need to be more careful, said Carol Breen, a DOT spokeswoman.

"People do need to watch the pavement markings, watch the signs and be cognizant of their speed," she said. "People need to be very cognizant about yielding. If we can get at that driving behavior, we can bring these accidents down."

So, the roundabout builders and operators blame the safety problems on the drivers! Apparently the drivers have gotten worse since the roundabouts were constructed.

Roundabouts are safer for other users than signalized intersections.

Do roundabouts pose problems and risks for other users?

All too often, roundabout proponents blur the well-documented "safety for cars" reputation into a blanket safety claim for all users. Safety of roundabouts is problematic for pedestrians, bicyclists, and motorcyclists, and there is little systematic or comparative safety information available. (If you know of some that I've missed, please contact me.)

Traffic enters, circulates, and exits a roundabout with random spacing. In my experience, there is no standardized use of car turning signals to indicate what movement a car is going to make. I believe these characteristics require extra judgment and introduce risk for pedestrians. NCHRP 672, 2nd edition, Roundabouts: An Informational Guide, in the section on "User Considerations", p.47, states

The two populations at opposite ends of the age continuum—children and the
elderly—and people with disabilities are particularly at risk at intersections. These pedestrians often find it more difficult to cross unprotected road crossings, walk at slower speeds than other pedestrians, and generally prefer larger gaps in the traffic stream. Children lack traffic experience, are impulsive, and have less developed cognitive abilities, and their small size limits their visibility. The elderly may have physical limitations including reduced visual acuity, hearing, and mobility.

This article from Sarasota, FL that says "Walkers rule". However, look at the picture with the Sarasota article-- pedestrians might rule, but are they safe? Also, check out this pro-roundabout video (mentioned previously), and watch the pedestrians. Safe? Personally, I feel safer when all traffic is stopped at a signal.

A 2009 ROSPA report (UK) on bicycle accidents states that "Roundabouts are particularly dangerous junctions for cyclists."

Motorcycle organizations offer special cautions about roundabouts. Bracknell Forest Borough (UK) has a motorcycle accident-prevention guide that states "At roundabouts, the most common accident type was another vehicle entering the roundabout in the path of a motorcyclist already on the roundabout." Pretty much the same danger that motorcycles face everywhere.

Roundabouts are subject to design flaws and these can have tragic consequences. In 2007 in Victoria, AU, three fatal motorcycle crashes occurred within a 6 month period. In London in 2009, a bicyclist was killed. Another motorcycle fatality occurred in Las Vegas, NV in 2010. The ROSPA (Royal Society for the Prevention of Accidents) "Cycling accidents fact sheet" states that "Roundabouts are particularly dangerous junctions for cyclists."

Several failed roundabouts seem to have fallen because of concerns for pedestrians and bikers: Bicycle Blvd. (Santa Rosa, CA), Lynch Roundabout (UK), and Highbury roundabout (UK).

Do roundabouts limit emergency response?

Experience and opinion on this seem to be mixed. Various fire and police departments have indicated they find no significant problems with emergency response times. Our own fire department states "We are not anticipating a significant increase in [response] time as there is still pull over room." On the other hand, I find it "obvious" that the complex road configuration proposed in the corridor study will restrict emergency responses in some cases. It's hard to imagine fire trucks zigging and zagging around roundabouts in the same length of time that they can negotiate a straight, open road. A tantalizing headline from newsday.com in Long Island, NY reads "Fire dept. decries town's roundabout plans". (Here's another case where an apparently legitimate news source has an accessible and interesting headline and lead-in, but subscription is required to see the article.)

I think the question of large-scale emergency response is clearer. A road with many obstacles and a concrete, in-place limitation on passage cannot perform as well in an evacuation as a wide-open multi-lane roadway. With an open-geometry road and supervision by qualified personnel, for example, 3 out of 4 thru-traffic lanes can be allocated to the egress direction without completely blocking necessary reverse flow.