While modern roundabouts generally increase safety for motorists in automobiles, several studies show this is not necessarily the case for what the literature terms "vulnerable road users" - bicyclists, motorcyclists, and pedestrians.
Bicyclists are particularly at increased risk in roundabouts with multiple lanes or with dedicated cycle lanes around the roundabout's perimeter. The typical accident is a cyclist circulating in the roundabout is not seen by a motorist entering the roundabout; roundabouts are yet another reason to follow the maxim of "pretend you are invisible" and to take the lane. One recent publication showing increased risk is Injury crashes with bicyclists at roundabouts: influence of some location characteristics and the design of cycle facilities.<http://www.ncbi.nlm.nih.gov/pubmed/19433206?ordinalpos=1&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_DefaultReportPanel.Pubmed_RVDocSum>J Safety Res. 2009;40(2):141-8. Epub 2009 Apr 8. They found that "roundabouts with cycle lanes appear to perform significantly worse compared to three other design types (mixed traffic, separate cycle paths, and grade-separated cycle paths). Nevertheless, an increase of the severest crashes was noticed, regardless of the design type of the cycle facilities. Roundabouts that are replacing signal-controlled intersections seem to have had a worse evolution compared to roundabouts on other types of intersections." This study is notable because it shows that some designs intended to make roundabouts safer for cyclists did not achieve that goal. These European authors have gotten a lot of kilometers out of this study since much of the same information is available as: Injury accidents with bicyclists at roundabouts. Influence of the design of cycle facilities and other location characteristics. (read beyond the initial part in Flemish/Dutch) at http://www.steunpuntmowverkeersveiligheid.be/modules/publications/store/150.pdf AND Stijn Daniels, Tom Brijs, Erik Nuyts, Geert Wets. Design types of cycle facilities at roundabouts and their effects on traffic safety: some empirical evidence. Velo-city 2009, Brussels, Tour & Taxis, May 14 2009. http://www.velo-city2009.com/assets/files/paper-Daniels-sub4.4.pdf AND Roundabouts and safety for bicyclists: empirical results and influence of different cycle facility designs' TRB National Roundabout Conference Kansas City, Missouri, USA – May 18-21 2008. http://www.teachamerica.com/rab08/RAB08_Papers/RAB08S8CDaniels.pdf OR you can see and hear the presentation at http://www.teachamerica.com/rab08/RAB08S8CDaniels/index.htm A nicely illustrated (but bit old; 2004) review of some roundabout features thought to improve bicyclist safety is: Bicyclists at Roundabouts: State of the Practice http://www.teachamerica.com/Roundabouts/RA055A_ppt_Moule.pdf Some additional studies of bicyclist safety (or lack thereof) at roundabouts are (regrets about the link lengths, I'm uncertain if embedded links will make it through): The effects of roundabouts on traffic safety for bicyclists: an observational study. Accid Anal Prev. 2008 Mar;40(2):518-26.<http://www.ncbi.nlm.nih.gov/pubmed/18329402?ordinalpos=1&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_DiscoveryPanel.Pubmed_Discovery_RA&linkpos=1&log$=relatedarticles&logdbfrom=pubmed>Epub 2007 Sep 14. http://www.ncbi.nlm.nih.gov/pubmed/18329402?ordinalpos=1&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_DiscoveryPanel.Pubmed_Discovery_RA&linkpos=1&log$=relatedarticles&logdbfrom=pubmed The 2005 TRB conference's "Review of Accident Research at Roundabouts" has a summary of roundabout cyclist safety research prior to 2005: http://www.teachamerica.com/roundabouts/RA052B_ppr_Kennedy.pdf Bicycle and Pedestrian Considerations at Roundabouts. Florida Department of Transportation. Summary of Final Report, WPI# 0510824 September 2000. at: http://www.dot.state.fl.us/Research-Center/Completed_Proj/Summary_SF/FDOT_824.pdf which found bicycle accidents at roundabout are 15 times that of cars. USDOT Roundabouts: An Informational Guide page 120 http://www.tfhrc.gov/safety/00-0675.pdf Exhibit 5-17. • Proportionally, two-wheel vehicle users were more often involved in crashes (16 percent) on roundabouts than at signalized intersections. Furthermore, the consequences of such crashes were more serious. 5.3.4 Bicyclists As shown in Exhibit 5-17, at British roundabouts bicyclists fare worse in terms of crashes at roundabouts than at signalized intersections. On Tue, Oct 13, 2009 at 2:59 PM, India Rose Viola <[email protected]> wrote: > > Mike, > > Consider me schooled. I look forward to trying out these new-fangled roundabouts! > > -India > > ----- Original Message ----- > From: Michael Rewey <[email protected]> > Date: Tuesday, October 13, 2009 2:57 pm > Subject: (Fwd) Re: About Roundabouts > To: [email protected] > > > > Hi India. One more lesson.... > > > > What you had out east was rotaries. For the most part they sucked and > > still do. What is > > being built now are "modern" roundabouts They are well engineered and > > work very well. > > Traffic signals are actually less efficient. For starters there is > > far less user delay on > > roundabouts (energy savings). No cost of maintaining signals. > > Function during power > > failures. Less frequent and severe crashes. Higher traffic capacity > > than most signalized > > intersections. I have biked on modern roundabouts in Madison, Mount > > Horeb, Florida, > > Denmark and Ireland to name a few. I love them. Very easy to traverse. > > > > The rotaries out east are NOT roundabouts. > > > > call... > > > > Mike > > 698-6673 > > > > > > ------- Forwarded message follows ------- > > Date sent: Tue, 13 Oct 2009 14:34:20 -0500 > > From: India Rose Viola <[email protected]> > > Subject: Re: About Roundabouts > > To: Michael Rewey <[email protected]> > > Copies to: [email protected] > > Priority: normal > > > > Mike, > > > > You are correct. I was referring to the circular traffic islands that > > look suspiciously like roundabouts, and so I casually wrote > > "roundabouts", because noone seems to know how to get around them. > > > > Roundabouts are another topic for discussion. Growing up on the east > > coast I saw roundabouts being replaced with newer, more efficient > > technology- traffic signals. Roundabouts (or rotaries, as we call > > them in Boston) are ok in some large intersections for cars only, or > > in some relatively quiet intersections in lieu of the 4-way stop (yet > > another topic for discussion)- but having bikes and cars in a busy > > roundabout is about as pleasant as biking on the interstate. Not very > > fun. > > > > That's my 2 cents. Thanks for the clarification. To sum up my > > opinions: Traffic islands suck. Roundabouts have their place, and > > biking on the interstate is both illegal (in most places) and > > unpleasant. > > > > -India > > > > *********************** > > India Viola > > UW-Madison > > Stretton Lab > > 115 Zoology Research Bldg. > > 1117 W. Johnson St. > > Madison, WI 53706 > > 608.262.3336 > > ***********************
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