SOMEONE in a car with tinted windows slaloming between lanes once pranged my bicycle鈥檚 back end on the Lambeth Bridge southern roundabout in London. The wheel ended up slightly squashed, but there was no damage to life and limb. As an impoverished student, the 拢200 cash offered to sort myself out, no questions asked, came in quite handy.
I mention this only because this very same roundabout, with iconic views of Big Ben and Parliament, features in a . Clark Griswold, played by Chevy Chase, is on a family holiday in London and trying desperately to exit it. In failed attempts to manoeuvre his bright yellow rental car from the inside to the outside lane, he suffers several near misses with other traffic. Night falls with the Griswolds still circling.
鈥淩oundabouts are a great win-win in terms of safety and keeping people moving鈥�
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Both scenes serve to transport us down a peculiar byway of technological progress: the vexed transatlantic history of the roundabout. This is a story to be entered cautiously, taking due note of already circulating traffic. And be warned: we may end up where we started.
Roundabouts have become part of the street furniture in many parts of the world. They are good at what they do, too. According to the US Federal Highway Administration (FHWA), a one-way gyratory system with four feeder roads . 鈥淭here鈥檚 two things,鈥� says Jeff Shaw at the FHWA. 鈥淔irst, they reduce speed through the intersection. And they trade off right-angle crashes for crashes that are more of a merging or a diverging type.鈥� I can vouch for that: it鈥檚 the reason I still have ankles.
Figures suggest that roundabouts are more efficient, too, allowing a greater number of drivers through than a signalled intersection, and reducing harmful exhaust emissions from vehicles idling at a red light. 鈥淚t鈥檚 really one of those great win-wins in terms of both the safety and the ability to keep people moving,鈥� says Shaw.
鈥淓arly roundabouts had a fatal flaw: traffic entering them had priority鈥�
The UK has certainly taken to roundabouts with abandon. A concrete number is hard to come by, but the country has something northwards of 25,000 of them, more than one for every 16 kilometres of paved road. These include bewildering classics such as Swindon鈥檚 鈥溾��, which is actually five interlocking roundabouts arranged in a giant circle. It divides the travelling public between awe and fear.
Since 2003, the UK鈥檚 Roundabout Appreciation Society has even produced books, calendars and other assorted memorabilia featuring roundabouts with particularly pleasing displays in the middle. 鈥淭hey lift our tiring spirits on long journeys with their colour, their inventiveness, with whatever goes on the roundabout,鈥� says Kevin Beresford, the society鈥檚 president. Its 2019 鈥溾�� is in Truro, Cornwall, and features giant, wooden sculptured hedgehogs.
For all the FHWA鈥檚 technocratic enthusiasm, such ardour is hard to find in the US. And yet the US was a pioneer: the world鈥檚 first formal one-way gyratory system was probably Columbus Circle in New York, built in about 1870. Many other grand-scale 鈥渞otaries鈥� were built in the US in the following decades, says traffic engineer , Oregon, who is an international authority on roundabouts and keeps a . So what changed? 鈥淲hat happened is the circular intersection fell out of favour here as a lot more automobile ownership took over,鈥� says Rodegerdts.
Early roundabouts also had a simple but fatal flaw: traffic entering them had priority. This is still the case in some corners of Europe and sets up natural conflicts with already circling traffic that are solved by a lot of weaving. As traffic speeds and volumes increased, the size of roundabouts were increased to allow more space for this weaving, which in turn encouraged higher speeds, and so on. 鈥淚t just kind of fed itself,鈥� says Rodegerdts. 鈥淚t was basically a dead-end solution.鈥�
The answer came in 1966 from an iconoclastic British engineer called Frank Blackmore at the UK鈥檚 Transport Research Laboratory. It seems obvious now: you reverse priority to make entering traffic yield to circulating traffic, and gently curve the approaches to the roundabout to make traffic slow down. This principle could be made to work on intersections of all sizes. It led Blackmore to pioneer a further innovation: the mini-roundabout. 鈥淚t鈥檚 such a simple invention, isn鈥檛 it?鈥� says Beresford. 鈥淛ust a painted blob in the middle of the road. It鈥檚 incredible and cheap and it does work fantastically well as opposed to traffic lights.鈥�
That wasn鈥檛 immediately obvious: Blackmore is said to have stood in the middle of the first of the new roundabouts in Peterborough and personally directed traffic movements. But his concept has since conquered large parts of the world. Australia now has some 10,000 modern-style roundabouts of all sizes. France has taken to them with particular 茅lan, leading the world with an estimated 32,000.
The US, meanwhile, has been on an alternative route to splendid isolation. With more space to play with and fewer of the fiddly, irregular intersections of the old world, it fell in love with simple controlled junctions. 鈥淵ou basically developed a mindset over generations of engineers to start with a stop-controlled intersection, and if that doesn鈥檛 work, you go to a traffic signal,鈥� says Rodegerdts.
It took a man with tunnel-visioned determination to change things. Impressed with what he had seen in Europe, in 1986 US engineer Leif Ourston enlisted Blackmore鈥檚 help to reintroduce the roundabout to US soil. 鈥淚n 1941, Sir Winston Churchill asked America to join Britain in a struggle to protect democracy,鈥� he wrote in a letter to Blackmore. 鈥淲e joined you and together we triumphed. Now, 45 years later, I am calling upon you to help me with a difficult struggle in which we are both engaged. We are trying to bring the British-style roundabout to the western hemisphere.鈥�
The pair toured California attempting to sell the concept, but to little avail. Transportation departments refused to believe that they could be safer. Fire departments warned they would be an obstacle to emergency vehicles. Most of all, polls showed that the roundabout鈥檚 underlying principle 鈥� yielding passage to circulating vehicles smoothly and according to your own judgement, rather than following a stop sign or traffic light 鈥� made the public angry and confused.
Ourston鈥檚 big break came in 1990, with permission to build two Blackmore-style roundabouts in a new development in the Las Vegas Valley. That, and other pioneering examples, started to prove that roundabouts could operate safely and improve traffic flows. In 1996, Rodegerdts, then a rookie engineer, was invited to help produce the first guide to roundabout design for the FHWA.
Part of the task in promoting wider adoption of roundabouts in the US is to overcome the innate conservatism of engineers there, says Rodegerdts. 鈥淭hey want to have something that鈥檚 proven, and they need to see it with their own eyes to believe it.鈥� Then there is lingering public scepticism. 鈥淥ne of the first things we tend to hear is that 鈥榩eople don鈥檛 know how to yield in my community鈥�,鈥� says Shaw.
Still, the idea is catching on. In recent years, more state and local governments keen to build roundabouts have started to approach the FHWA for help convincing sceptical voters. One response has been to institute a 鈥溾�� in which the roundabout-friendly . The second one was held in September 2019. 鈥淟et people kind of absorb it, you know, in a general sense, just to hear more about them, to learn more about them,鈥� says Shaw.
From just a few hundred maybe a decade ago, Rodegerdts鈥檚 numbers suggest something like 5000 roundabouts are now spread across the US. He is cautiously optimistic things are turning the corner. 鈥淚t鈥檚 still very uneven, some areas are still much more roundabout-accepting than others,鈥� he says.
Round and round it goes
The US capital of roundabouts is , Indiana, which now has more than 100 鈥� and proudly bangs the drum for their introduction. But about 20 per cent of states now have a policy of looking to see whether a roundabout might be the best solution for an intersection, says Rodegerdts 鈥� and often find they are.
The irony is that, in the UK, things are starting to turn the other way. Increased traffic has encouraged the building of ever bigger, multi-lane roundabouts that are an obstacle to pedestrians and a mortal danger to cyclists (amen to that). In some circles, a movement away from roundabouts is seen as a way to break the tyranny of the motor car. Increasingly, too, high traffic volumes have undermined the whole free-flowing point of the roundabout, forcing planners to introduce traffic signals on roundabouts so that continuously circulating traffic doesn鈥檛 stop people ever getting on.
Or indeed off. If Clark Griswold鈥檚 travails on the Lambeth roundabout exemplified the US鈥檚 bemused relationship with the concept three decades ago, they have proved an unexpected boon for the pro-roundabout faction today. 鈥淎nytime there鈥檚 a Facebook page dedicated to a proposed roundabout, it鈥檚 almost a given that somebody will post the GIF of the scene from that movie,鈥� says Shaw. 鈥淲e鈥檝e been able to turn that around as a great talking point and say, you know what, this is not what we鈥檙e building.鈥�
The notoriety seems to have stung someone in London, too. Transport for London, the body responsible for the city鈥檚 key junctions, has 鈥� with a four-way signalled intersection.
