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I'm both a car driver and a cyclist. There are a zillion roundabouts in the country I'm living in. This is my experience and I'd like to hear a traffic designer

I'm both a car driver and a cyclist. There are a zillion roundabouts in the country I'm living in. This is my experience and I'd like to hear a traffic designer about it. Roundabouts feel safer than a 4 way intersecting when I'm in a car even if it's annoying to have to slow down and accelerate again when there is very little or no traffic, which is normal in the countryside. It also consumes more fuel, wears the car, adds to pollution. It's different when I'm riding my bicycle. Roundabouts put me closer to cars, especially if there are traffic dividers that force cars closer to the side of the road. Then cars are usually slower than a bicycle in a small or medium sized roundabout (think of race bicycles with drop bars,) which adds up to chances of being packed between two cars. My feeling is that what's good for cars is bad for bicycles. As a cyclist I can see what's around me much better than when I'm in my car. Intersections don't feel like a problem because of the extra visibility. When I'm riding I long for old times straight roads, with a line on the side and half a meter of asphalt on the other side to ride on. No roundabouts, no speed bumps especially the 3M style plastic ones, which I can jump but they are annoying. All those safety devices, including roundabouts, increase fatigue and danger. They are also the main reason for crashes in bicycle races but that's not an issue for normal people. Finally, as I both drive and ride I know how to behave not to put in danger the cyclist. When I drive I don't overtake bicycles before a roundabout because they'll be at least as fast as me. I don't overtake when there is a short traffic divider which narrows the road. A long one, oh well, I have to. Same thing when I approach an intersection where I have to yield or stop. Bicycles will be definitely faster there because they can look around better than me and decide what to do quickly. When I ride and I'm approaching a roundabout or entering a short narrowing of the road I look behind me and if it's safe I lean a little to the center of the road to prevent cars to overtake when they'll be forced to come close to me.

axiolite 3y ago
Your observations are quite apt. "Researchers in Belgium found that single lane roundabouts without a protected bike lane increased crashes by 93%, while Danish researchers said roundabouts that did have separated lanes saw an 84% reduction in crashes." CNBC: Roundabouts Are Safer. So Why Does The U.S. Have So Few Of Them? https://www.youtube.com/watch?v=atORPw-w83I https://www.youtube.com/watch?v=atORPw-w83I
usrusr 3y ago
Ah, those traffic dividers, clearly designed by people assuming that all roads should be limited access... "All those safety devices, including roundabouts, increase fatigue and danger." They literally distract from the traffic when you aren't in a little isolated house on wheels where people are prone to forget that traffic even exists. All those things designed to help getting a driver's eyes off WhatsApp require cyclists to get their eyes away from traffic. On the topic of roundabouts, one thing I rarely see discussed (never?) is that traffic lights conveniently compress the vehicle stream into packets of high and low intensity, greatly helping smaller intersections downstream. Roundabouts on the other hand flatten the vehicle frequency and of there's a difficult place to enter or cross the stream, even a modest amount of traffic can be too much. In the end everything that isn't a roundabout can only be navigated by relying on someone in the dominant stream showing off compassion with those waiting. This makes everything go even slower and you quickly end up with even dominant streams going less than walking speeds. I have a hypothesis that roundabout-dominated road graphs are particularly prone to effective throughput dropping once a certain threshold of throughput demand is reached. Traffic light dominated graphs are immune to this if drivers are just a little careful to not enter an intersection before they can assume that they will be able to leave before the lights change.

axiolite 3y ago

Your observations are quite apt. "Researchers in Belgium found that single lane roundabouts without a protected bike lane increased crashes by 93%, while Danish researchers said roundabouts that did have separated lanes saw an 84% reduction in crashes." CNBC: Roundabouts Are Safer. So Why Does The U.S. Have So Few Of Them? https://www.youtube.com/watch?v=atORPw-w83I https://www.youtube.com/watch?v=atORPw-w83I

usrusr 3y ago

Ah, those traffic dividers, clearly designed by people assuming that all roads should be limited access... "All those safety devices, including roundabouts, increase fatigue and danger." They literally distract from the traffic when you aren't in a little isolated house on wheels where people are prone to forget that traffic even exists. All those things designed to help getting a driver's eyes off WhatsApp require cyclists to get their eyes away from traffic. On the topic of roundabouts, one thing I rarely see discussed (never?) is that traffic lights conveniently compress the vehicle stream into packets of high and low intensity, greatly helping smaller intersections downstream. Roundabouts on the other hand flatten the vehicle frequency and of there's a difficult place to enter or cross the stream, even a modest amount of traffic can be too much. In the end everything that isn't a roundabout can only be navigated by relying on someone in the dominant stream showing off compassion with those waiting. This makes everything go even slower and you quickly end up with even dominant streams going less than walking speeds. I have a hypothesis that roundabout-dominated road graphs are particularly prone to effective throughput dropping once a certain threshold of throughput demand is reached. Traffic light dominated graphs are immune to this if drivers are just a little careful to not enter an intersection before they can assume that they will be able to leave before the lights change.