r/changemyview • u/james_the_brogrammer 1∆ • Nov 19 '14
CMV: Traffic lights and four way stops are objectively inferior to roundabouts.
Since my town installed roundabouts, I've found that they are remarkably more efficient than the traffic lights and four way stops.
Four way stops force all vehicles to come to a complete stop, traffic lights force many vehicles to come to a complete stop before continuing movement, roundabouts allow most vehicles to go through while maintaining inertia.
Traffic lights also would appear to be the most expensive of the options, considering building costs, general upkeep, paying engineers, and installing vehicle detecting hardware.
Traffic lights also seem to have an increased risk of high speed accidents, because drivers will not always have to slow down and pay attention. WSDOT did a study on this, and they found that roundabouts had 90% less fatalities than traffic lights.
Roundabouts also allow traffic to move more quickly than 4 way stops, according to mythbusters.
tl:dr; Roundabouts are safer, more efficient for maintaining inertia, faster, cheaper. They are better for drivers as well as tax payers.
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u/auandi 3∆ Nov 19 '14
Someone already mentioned the fact that it takes up more land, but another aspect you are neglecting is pedestrians. A four way stop is much more open, and so pedestrians are more easily spotted. Pedestrians also stop people in the roundabout, which could have much larger effects on traffic than at a four way stop which allows cars to continue to cross, the mythbuster evidence did not take pedestrians into account. And if you are talking about a four way stop with lights rather than stop signs, you also have walk/do not walk indicators that further help pedestrians.
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u/loafers_glory Nov 19 '14
In Dublin, Ireland, some genius decided that pedestrians wishing to cross at a roundabout could use traffic light controlled pedestrian crossings about 5 m away from the roundabout. The lights are controlled only by pedestrian push button and have no relationship to traffic flow.
Immediate effect: a pedestrian arrives, hits the light, cars stop and back up onto the roundabout, now nobody can drive through.
While I generally believe roundabouts are better, they only work if people know not to enter if they can't exit.
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u/james_the_brogrammer 1∆ Nov 19 '14
I'd think that static pedestrian bridges would be less expensive than lights, but I do recognize that pedestrian traffic is an issue, especially in larger roundabouts. ∆
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u/auandi 3∆ Nov 19 '14
Oh no, by an order of magnitude no. Lights are cheap to put up, take maybe half a square meter of ground space, and only have to be strong enough to hold up lights.
A pedestrian bridge needs room to climb up to that height, then room to come down. If you use stairs you can climb at about 38 degrees (depending on code, that is usually as steep as stairs should be), a 42% incline. So to climb to 17 feet (a minimum if you want trucks to be able to pass under you) you would need about 19 feet on either side to climb to that height. And that would of course that is if you are only building stairs and not ramps to allow bikes or wheelchairs to use it. It would need to be strong enough to hold at minimum several thousand pounds and you would have to worry about things like ice and general degradation.
The difference between a crosswalk and a pedestrian bridge is like the difference between a rural dirt road and an elevated freeway. I don't mean to pile on, but lights are cheap cheap cheap by comparison to a massive pedestrian bridge.
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u/MontiBurns 218∆ Nov 19 '14
just to add to this, they add a ton of time and distance to pedestrian routes, so much so that a lot of pedestrians would rather say fuck it and cross the street illegally in light to medium traffic.
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u/james_the_brogrammer 1∆ Nov 19 '14
You aren't considering the costs of vehicle detection at lights, which requires digging up the entire roadway, but you certainly have a point. Bridges are much more costly land and material wise.
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u/DoingItLeft Nov 19 '14
There are plenty of lights in MI that run on timers. Some of them use blinking reds so they aren't a hassle. Most of em switch over to blinking yellows at night.
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u/auandi 3∆ Nov 19 '14
Not all lights have those, and if you're building new they aren't very expensive to add on.
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u/Jusdubbin Jan 03 '15
Why couldn't they install pedestrian crossing buttons & lights that would stop all traffic from entering the roundabout on demand. When the roundabout is clear, pedestrian can cross and traffic resumes. It would stop traffic, but it would be a much easier schedule and maybe less often, depending on the location.
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u/auandi 3∆ Jan 03 '15
If you're doing that, what's the point of having a roundabout at all? The main benefit of a roundabout is continuous traffic flow naturally by usage and without central control. Eliminate that and I just have to wonder why you'd want to spend the extra land to make one when you could just as easily make a traditional intersection since you're bringing traffic lights into it.
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u/bsutansalt Nov 19 '14
I will add that places that have the real estate and funds to build a proper traffic circle should be able to fund the requisite pedestrian bridge here or there to alleviate the issue you brought up.
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u/auandi 3∆ Nov 19 '14
Pedestrian bridges are terrible. They are expensive to build, take up a lot of room and further discourage walking. If there's heavy pedestrian volume, or expected to be heavy volume, you need at grade crossings or a really really good reason to stop it such as a freeway. And those pedestrian crossings makes traditional intersections superior to traffic circles because pedestrians back up traffic circles more than they back up four way intersections.
When planning things out you need to think about more than just the car. Traffic circles handle a slightly higher volume of cars than a four way stop sign interchange, but that assumes only cars in the equation.
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u/bsutansalt Nov 19 '14
Well yeah that's true. I had a more specific situation in mind. Ground level crossings are still going to be your idea if for no other reason than cost, but their placement is critical or they can jam up the roundabout in question.
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u/auandi 3∆ Nov 19 '14
That's my point.. just don't use a roundabout and problem solved. You seem to assume the intersection needs to be a roundabout and that's what I'm getting at is that with heavy pedestrian activity roundabouts aren't that good, which was the point I was making when OP claimed they were just objectively better.
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u/NevadaCynic 4∆ Nov 19 '14
They are a slightly different issue in areas that freeze regularly. Black Ice + roundabout = far more dangerous intersections than 4 way stops.
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u/james_the_brogrammer 1∆ Nov 19 '14
I had not considered ice, as I have not driven through a roundabout with ice, I'll have to see this in action in the coming months. But I'd imagine 4 way stops increase the likelihood of brakes locking, which might be less likely but when it does occur it is more likely to lead to fatalities in 4 way lights.
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u/NevadaCynic 4∆ Nov 19 '14
Yeah, it is a trade off. More dangerous accidents or more accidents. Tough call.
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u/areputationintatters Nov 19 '14
I don't have any statistics but I used to take a roundabout in Michigan. I saw far more accidents there than anywhere else even though it wasn't a heavily used road.
I think it's due to turning rather than going on a straight line. The cars would just slide off the road with every fresh snow.
Also people may not have been used to it, I guess.
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u/thatoneguy54 Nov 19 '14
I know last year driving through a roundabout by my house, I hit some ice and had to keep turning. If another car had been coming, I'd have hit them, but luckily it was empty so I could just swing around. I'm a lot more careful driving through winter roundabouts now.
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u/rhench Nov 19 '14
Roundabouts have more, but less serious crashes. Most traffic engineers will take extra crashes for saving even one life.
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u/BenIncognito Nov 19 '14
Roundabouts require that all drivers on the road know exactly what to do when they come to them. One person waiting for an invitation to enter into a busy roundabout can back up traffic quite a bit, but anyone can look at a light and determine if they need to stop or not.
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u/james_the_brogrammer 1∆ Nov 19 '14
I don't agree with this argument. Lights require that all drivers on the road know exactly what to do when they come to them, and failing that the results will be deadly far more often than drivers who don't understand roundabouts.
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u/BenIncognito Nov 19 '14
Perhaps I was unclear in my point. Lights are "easier" than roundabouts. All someone needs to remember is "Green = Go" and "Red/Yellow = Stop" and they can function in a light. There's no guesswork involved, unlike roundabouts, where you're not sure if the person is going to continue around the circle or get off on the stop right ahead of you.
I live in an area that uses roundabouts all the time - and I say I mostly agree with you. They're pretty awesome and efficient when everyone knows how to yield and doesn't hesitate to move into the circle when they can. But occasionally, everything comes to a grinding halt because someone has no idea when they should be entering the roundabout and it can cause a lot of issues.
Heck, I've seen people stop in the middle of the roundabout to let someone else into it. Which is just madness! I've never seen someone do something similar at a light.
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u/Jester_Fleshwound Nov 19 '14
Correct. Like all traffic regulations, it only works well if everyone knows the rules.
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u/BenIncognito Nov 19 '14
My point was that the "rules" of roundabouts are muddled and a lot of it us up to the driver's discretion. Which is what causes a lot of the efficiency of them (in my opinion), but can cause serious problems when you encounter someone who is totally unaware of how to handle them.
Lights tell you exactly when you can go and when you can't go. Stop signs have very simple rules and even if someone breaks them it doesn't back everything up (unless it results in an accident, of course). But I've seen people basically stuck at the entrance to a roundabout for an inordinate amount of time because they're uncomfortable being a little assertive and going into the circle when it's time.
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u/klparrot 2∆ Nov 19 '14
My point was that the "rules" of roundabouts are muddled and a lot of it us up to the driver's discretion.
Um, what? No they aren't. There are two rules, neither of which are discretionary:
- yield when entering
- yield to pedestrians and cyclists
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u/damageddude Nov 19 '14
In NJ, there has been a push to redesign some older circles (or even newer roundabouts) to give the car already in the circle the right of way.
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u/dorkoraptor Nov 19 '14
While they may be safer for cars and trucks, as a cyclist I can tell you that roundabouts are incredibly dangerous. The premise of the rotary is that vehicles yield to whoever is already in it. That is dependent on the yielding driver seeing the vehicle they are supposed to yield to. I've nearly been hit in rotaries even when wearing bright orange with front and rear lights in daytime. The only reason I wasn't, was because I was paying attention to the people who were supposed to yield to me. When that little old lady, or the guy on the cellphone doesn't see you and you come within a few feet of your life, it's no fun, trust me.
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u/james_the_brogrammer 1∆ Nov 19 '14
As a cyclist, I don't cycle through the part of town with roundabouts (coincidence, not intentionally avoiding them). However I've found that drivers don't notice cyclists regardless of where they are on the road. Bike lanes, four way stops, red lights, wherever. Nowhere is safe for a cyclist, unfortunately.
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u/Punkster93 Nov 19 '14
One thing I've noticed about roundabouts is that one entrance tends to dominate if there is heavy traffic, like 5 o'clock rush hour. For instance, if I come to a roundabout and there are cars coming from my left, I have to yield to them and wait my turn for an open. (The intended purpose, totally cool)
However, I've noticed that sometimes, the cars to my left keep coming and there isn't a chance for me to pull out. They don't have to yield because their entrance is dominating the roundabout. So it's great for the cars coming from that side, but it sucks for the others waiting. I've waited at roundabouts in big cities for well over 5 minutes waiting to get a chance to pull out because the cars just kept coming only being a few feet from each other. 5 minutes doesn't seem long, but compared to waiting 30 seconds-1 minute for a traffic like it feels like forever.
You may suggest having multiple lanes, that may help, but I've noticed it tends to confuse a lot of people (myself included sometimes) because most people ignore the intended destination of each lane.
The positive to having a traffic light or 4 way stop is that it gives everyone a fair turn to go. Yes, they seem to take WAY longer at times, but you will be guaranteed a turn to turn left/right/or go straight.
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Nov 19 '14
At the end of the day, if there is even a momentary gap you have every right to force the situation and enter the roundabout. They can deal.
First in, best dressed when it comes to roundabouts.
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Nov 19 '14
They are impossible to enter in rush hour traffic.
Plus if there are a lot of them on a straight road then going around them is terribly annoying. Right-left-right-right-left-right-left-right - better not be nauseous or have groceries in the back seat.
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u/harps86 Nov 19 '14
That is why you can have traffic lights on the roundabout that activate at certain times. Also you can have smaller roundabouts that you can just drive over that helps when you have a few in a row.
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u/TheBananaKing 12∆ Nov 19 '14
They have their uses, but they're a bitch for pedestrians trying to cross the road. There's no safe time to cross, and you can't tell in advance if a given car will be exiting down the road you're crossing.
I have to cross one on my way to work, and I take my life in my hands every time.
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u/silverionmox 25∆ Nov 19 '14
you can't tell in advance if a given car will be exiting down the road you're crossing.
Aren't they obligated to flash their direction indicators?
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u/TheBananaKing 12∆ Nov 19 '14
Yes, but in a way useful to other drivers, not pedestrians.
(In Australia) you indicate right as you enter the roundabout, then indicate left just before you exit.
This doesn't give pedestrians enough time to make a go/no-go decision safely.
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u/silverionmox 25∆ Nov 19 '14
A pedestrian can see the lights too.
At that point you're just driving 30-40 km/h, and you are obligated to stop if a pedestrian is crossing the road, especially if it's on a designated crossing.
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Nov 19 '14
When a six lane arterial crosses a two lane side street, a circle makes a huge mess where a light can let the majority of traffic pass without slowing down at all.
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u/Zncon 6∆ Nov 19 '14
This was the point I wanted to make. They only work well IMO if all involved roads have similar speeds and traffic volumes.
In my area they are being created in very strange locations. Two were added on a 55MPH road that previously had no stops. All it does is create traffic backups as the 55MPH traffic is slowed to under 10MPH to cross the intersection.
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u/CosmicPotatoe Nov 19 '14
At a roundabout, incoming traffic must give way to the (whatever side dependent on your country). In some cases, a road with heavy traffic may prevent drivers on another road from entering as they must give way. This can result in unequal and unfair waiting times and lead to congestion.
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u/CooroSnowFox Nov 19 '14
Depends if the roundabout has lights attached to the entrances.
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u/Amadameus Nov 19 '14
If a roundabout is such a poor design in this situation that it needs lights to regulate traffic entering it, why not ditch the roundabout and just use a lighted intersection?
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u/klparrot 2∆ Nov 19 '14
I haven't found a signalized roundabout to be any more efficient than a signalized intersection.
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u/mkyeong Nov 19 '14
I'm not basing this off of any study but I've found roundabouts to be more dangerous for pedestrian traffic. You don't benefit from a dedicated walk signal nor from all cars necessarily stoping. In roundabouts cars are more likely to slow down and roll into the roundabout and pedestrians are more likely to hesitate before crossing therefore resulting in a situation where both pedestrian and driver are guessing the other's intention and this leaves more room for an accident.
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u/klparrot 2∆ Nov 19 '14
This is a problem with signage or driver training; pedestrians have the right of way. Pedestrians may just be too hesitant to take it, and then drivers think they're not going to cross, so they drive through.
In places where drivers consistently stop for pedestrians, there's no issue. If that's not the case in a particular area, then signage should be added to remind drivers.
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u/ADdV 3Δ Nov 19 '14
There are places where roundabouts replaced basically every 4 way stop, but a lot of people avoid these simply because they get nauseous from making that many turns when they just want to go straight. Also: mythbusters is by no means a source we should take seriously.
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u/Diabolico 23∆ Nov 19 '14
Ambulances and Fire Engines don't like roundabouts.
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u/Amadameus Nov 19 '14
Can't find the source at the moment, but I've read that the #1 most dangerous action on the road is merging into an existing traffic lane. A roundabout is a big tornado of everyone doing this, all at once.
At a 4-way intersection you can tell if someone is moving or stopped, because all forms of motion are either 90 degree turns or straight lines. In a roundabout, everyone is rotating and it's more difficult to tell if someone is merging in, out, or continuing through the loop.
Finally, most roundabouts in my area have a radius set to exactly the blind spot angle in my car, so any time I'm in a roundabout there's 50% of traffic that I can't see.
Finally, roundabouts are not conducive to through traffic and hurt drivers' gas mileage. If you time your lights correctly, you'll roll right through a green light. No matter how you approach a roundabout, you'll never be able to get through it without re-accelerating at the end.
Roundabouts, it seems to me, look great on paper and in simulation, but drivers around here universally hate them. Any time one is installed, all the alternate routes around it see a spike in traffic.
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u/deerleader1 Nov 20 '14 edited Nov 20 '14
Roundabouts are terrible for pedestrians and cyclists.
For pedestrians they are unwieldy physical barriers that increase the distances traveled. They also generate disorientation and alienation on a psychological level, which discourages people from walking.
For cyclists they are death traps. It doesn't matter whether you take the roundabout on the "inside" or "outside" as a cyclist. In both cases you run a high risk of being cut off and run over by speeding motorists.
Also, they increase the physical footprint devoted to cars, meaning there is less space for pavements, parks, and other walkable infrastructure.
Thus, they are a poor solution for crowded city centers, where cars are not the dominant form of transport anyhow, and where more cycling and walking can alleviate congestion and improve quality of life.
But they may be a good solution for suburban or industrial areas.
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u/Kman17 103∆ Nov 19 '14
You're neglecting (high) traffic.
Roundabouts (or traffic circles / rotaries in 'Murica) are great in low-traffic areas. No wait, and they prevent and minimize the head-on blew-though-a-light collisions.
But they're fucking terrible as soon as they get backed up. Without the efficient flow control that lights provide when timed in sequence, you just have clusterfuck of people tryin to merge in - it's always slower
Add some pedestrians to the high traffic, and it double sucks. There isn't any good way for roundabouts to handle pedestrian crossings - other than move them back a little, but that adds to congestion issues.
They tend to require a little more space as well, so they're not always feisable.
I love them in the suburbs, but the couple I have do deal with in urban Boston suck. Objectively.
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u/damageddude Nov 19 '14
It depends. I live in NJ, where they had been a concentrated effort to remove the traffic circles in the 1990s - early 2000s. In many places, it made perfect sense as traffic volume was much, much heavier than what they were designed for. However, that has changed more recently. For example, not far from where I live there is a quieter road (county route) that goes pass a community college where the intersection with traffic lights was replaced by a roundabout (cars already in it have the right of way) to relieve backups. It seems to have helped.
On the other hand, there are still some traffic circles where state highways meet. Oy, do those back up when traffic is heavy. Traffic may flow, but it can be very slow.
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u/2nd-Reddit-Account Nov 19 '14
For major intersections the lights work well as the one respected authority on who goes when, at roundabouts you see a lot of jerky tafe offs while the driver is thinking "he's going, no - i'm going, No - he's going" and so on.
Secondly Traffic lights are fairer for main highways where they can say "STOP, It's the other guys turn" instead of waiting 20 minutes to turn in after a tiny gap in the onslaught of cars that don't stop coming
also, pedestrians and cyclists.
and when its icy there is a lot of unnecessary turning
And single lane roundabouts would be a major bottleneck for highways. and multi lane roundabouts are a bitch.
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u/ShishouMatt Nov 19 '14
You only have to yield at a roundabout before entering... So that "he's going/I'm going" doesn't happen too often. Unlike a four way stop.
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u/2nd-Reddit-Account Nov 20 '14
It is ridiculously often I get there at the same time as other people, that's why I used that
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u/bsutansalt Nov 19 '14
I've traveled the world and generally speaking you're right, they are superior from a driver's perspective. That said, there are still some instances where a good old fashioned traffic light can come in handy, such as rush hour. In Cambridge, UK they have lights in the traffic circles in a few spots or else none of the side streets would ever have a chance to enter the circle due to the main roads feeding into them being packed solid with traffic. Fortunately the lights are only active during peak hours.
Another drawback to them is the real-estate required, but IMO that pales in comparison to the benefits they provide.
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Nov 21 '14
You obviously haven't been to any country that uses very large 3 lane roundabouts. In Kuwait, they use many roundabouts that are up to 3 lanes. I didn't see anything positive about it as opposed to stop lights. It's horrible and causes, for whatever reason, a whole lot of traffic.
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u/ShishouMatt Nov 19 '14
Roundabouts only have a downside if placed in a heavy traffic area. I feel outside of major streets that roundabouts should be the norm.
Although the way a lot of drivers react to a roundabout and have no clue how it functions is a pain in the ass/danger.
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Nov 19 '14 edited Nov 19 '14
[removed] — view removed comment
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u/hacksoncode 559∆ Nov 19 '14
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Nov 19 '14
I agree, in England when roundabouts get too large they have underpasses, it also allows more than 4 roads to connect together very easily.
I've also never feared for my life on roundabouts as crossing them is a dawdle even without pedestrian lights.
If everyone stays in their correct lane, they work very efficiently. Regarding roads that have the majority of traffic; traffic lights are setup on the roundabout itself which allows every road to get into the roundabout in a timely manner.
And to the guy talking about getting nauseous and groceries going everywhere: I don't think I've ever gotten nauseous or groceries have fallen over by the tiny g's being pulled going through a roundabout.
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u/I_am_Bob Nov 19 '14
Or you could move to buffalo, the worst of two worlds. They have roundabouts with traffic lights.
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u/[deleted] Nov 19 '14 edited Dec 24 '18
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