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You are here: MacNN Forums > Community > MacNN Lounge > Roundabouts - aka Traffic Circles - vs Traffic: Winning?

Roundabouts - aka Traffic Circles - vs Traffic: Winning? (Page 2)
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Doc HM
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Dec 13, 2019, 06:43 PM
 
Originally Posted by Waragainstsleep View Post
Roundabouts are awesome. Except when you start incepting them.

You see the ladder fire engine outside the fire station top rightish?

My house is about three doors further up just out of shot. (really)

I get a lot of practise on that roundabout. It works a lot better than you would think.
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Doc HM
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Dec 13, 2019, 06:46 PM
 
Also
https://www.redbull.com/gb-en/videos...gic-roundabout
Unbelievably I entirely missed it. Slept right through the filming!!
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ghporter
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Dec 13, 2019, 06:47 PM
 
Changing lanes in an intersection is not mentioned anywhere in the Uniform Vehicle Code, going back as far as 1965.

I too was taught that this wasn’t kosher, but I can’t find any solid reference that says it’s illegal.

Here is the complete Texas statute, remarkably similar to the UVC except for a few areas where Texas is “different” (toll roads, etc.). There is quite a bit about roundabouts (rotary roadways), and the usual stuff about speeding, yielding, seat belts, and so on, but nothing about changing lanes in an intersection. Unless it’s worded so obscurely that I just couldn’t see it...

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reader50
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Dec 13, 2019, 10:27 PM
 
Some googling indicates it is indeed not listed as illegal in CA, though I could swear my original Drivers' Ed class said it was. Beware that "Unsafe Lane Change" is a catchall ticket, and you're likely to get one if there's any other traffic in the intersection. The local cop revenue officer will be happy to pull you over.

It does vary by state. Ohio is specifically listed as being illegal. Apparently others too, though I didn't find a list.
     
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Dec 14, 2019, 11:02 PM
 
All lane changes must be done “safely,” and I think this is the key for driver training courses banning lane changes in an intersection.

For a new driver, intersections can be pretty confusing, so forbidding lane changes in an intersection does two things. First, it takes away the option to make a major error while trying to make sense of the intersection. Then it emphasizes getting into the right lane for what you plan to do well before the intersection.

Clearly, the idea of “planning ahead” has fallen out of favor in most driver training lately....

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subego
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Dec 15, 2019, 04:16 PM
 
Originally Posted by OreoCookie View Post
Easier, because cars have to slow down anyway. In a rural and suburban setting, they are great: they are cheaper than traffic lights, little maintenance, and if you space them closely enough, they act as speed bumps (which can be desirable in suburbia).
At a traffic light, motorized traffic is instructed to come to a complete stop. If reduction of speed makes yielding to pedestrians easier, a speed of zero is easiest.

Other things which make it harder to yield are the increased attention required to make a turn versus traveling straight, the increased attention it takes to deal with a more complex street pattern (like a roundabout), and that people accelerate out of a turn.

Further, a motorist will be less inclined to yield if there’s another motorist behind them. The chief feature of roundabouts is they cause this very scenario.


I went through the links. Were they intended as general data on roundabouts? Very little had to do with pedestrians.
( Last edited by subego; Dec 15, 2019 at 05:04 PM. )
     
OreoCookie
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Dec 16, 2019, 12:27 AM
 
Originally Posted by subego View Post
At a traffic light, motorized traffic is instructed to come to a complete stop. If reduction of speed makes yielding to pedestrians easier, a speed of zero is easiest.

Other things which make it harder to yield are the increased attention required to make a turn versus traveling straight, the increased attention it takes to deal with a more complex street pattern (like a roundabout), and that people accelerate out of a turn.
But motorists don't always come to a stop for many reasons (perhaps because they are inattentive or they think they can make a yellow by flooring it. In any case, the data I have linked to seems to bear out my arguments very well, that roundabouts are safer in general and in particular for pedestrians.
Originally Posted by subego View Post
I went through the links. Were they intended as general data on roundabouts? Very little had to do with pedestrians.
It was supposed to be general, but a few dealt with pedestrians explicitly (including 40 % reduction of accidents with pedestrians and 90 % less fatalities in accidents).
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Laminar
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Dec 16, 2019, 08:01 AM
 
Originally Posted by OreoCookie View Post
But motorists don't always come to a stop for many reasons (perhaps because they are inattentive or they think they can make a yellow by flooring it.
If the traffic light is yellow, pedestrians won't be attempting to cross in that direction, that's not an issue.
     
subego
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Dec 16, 2019, 01:37 PM
 
Originally Posted by OreoCookie View Post
It was supposed to be general, but a few dealt with pedestrians explicitly (including 40 % reduction of accidents with pedestrians and 90 % less fatalities in accidents).
Since it was posted in direct reply to a question about pedestrians, it leads to the conclusion they’ve been posted to support an argument about pedestrians, which forces the polite debater to go through link after link, spending large amounts of time searching for buried or non-existent data about pedestrians.

I’d like to see where the figures in that WDOT bar graph came from. It cites the FHWA and the IIHS. The FHWA appears to have a single, 20 year old, 400 page doorstopper, with no pedestrian data of its own, just cites from even older European studies. The IIHS’ own studies are strictly comparisons between single and multi-lane roundabouts. They come to the conclusion multi-lane is worse for pedestrians. The IIHS has a web page where they make some claims about pedestrian safety, but those are based on European studies, most of which aren’t in English.

Going through all this data, I have absolutely no idea how the WDOT came up with that 40% number.

If accurate, I’m not sure the 90% number applies to pedestrians. Most roundabout studies are about vehicles. I can’t assume it’s applying to all users unless it explicitly states it is.

I’m a little busy today, but when I have a chance I’ll dig up some links which specifically deal with pedestrians.


Edit: to be clear, the number for pedestrians could be better than 40%. The FHWA seemed to have evidence of this. I’m not saying I’m right, that’s for the data to say, but I can’t attach that number to either of the sources they cited... I should say numbers. I couldn’t get any of them out that source material, though I didn’t read all 400 pages of the FHWA doc.
( Last edited by subego; Dec 17, 2019 at 01:30 AM. )
     
reader50
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Yesterday, 05:13 AM
 
An example roundabout in a town nearby. This used to be a normal intersection of 4-lane roads. With signal lights. Some misguided person changed it to a 1-lane roundabout, and narrowed both roads to 2-lane, by giving both roads wide bike lanes. Which I have yet to see any bicycles in. There are cross walks, but no stop signs to protect pedestrians. Or buttons to push, for the missing signal lights to protect them.



Note the elevated whatsit in the center, blocking driver view across. When I first approached it after the downgrade, I thought the road was closed with a barrier. Driving across that could cause serious suspension damage. Now I just see the fail.

The message seems to be: stay off the roads around here. It's worked too - I won't go that way unless I'm taking a picture. That thing is dangerous, and may be a deliberate choke point.

I'd be fine with a state proposition banning construction of new roundabouts.
     
andi*pandi
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Yesterday, 12:07 PM
 
The new trend in traffic calming seems to be reducing lanes and adding bike lanes. And for some roads thats the only way to add bike lanes, so I get it... If you build it, they will come. We want fewer cars, which means encouraging bikes more... but the bike people ddon't feel safe.

We had a 4 lane road that turned into a 3 lane road with bike lanes. So one way only has one car lane, and if someone is turning it blocks up everything down the line.
     
subego
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Yesterday, 12:36 PM
 
The safest design seems to be a “protected” bike lane, where the bike lane is between the sidewalk and parked cars instead of parked cars and the street. The only problem I can see with it is I’m sure there’s a much higher incidence of cyclists getting “doored”, since passengers don’t have any experience having to check for cyclists before opening the door.

It’s not like drivers are great about that either, but at least some learn they should check for oncoming cars, which tangentially benefits the cyclists.

As far as roundabouts are concerned, I get the impression the best practice is also some form of “protected” option, but I didn’t see an example of how that’s implemented.
     
OreoCookie
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Yesterday, 11:12 PM
 
Originally Posted by andi*pandi View Post
The new trend in traffic calming seems to be reducing lanes and adding bike lanes. And for some roads thats the only way to add bike lanes, so I get it... If you build it, they will come. We want fewer cars, which means encouraging bikes more... but the bike people ddon't feel safe.
And it could also improve the flow of cars, because bicycles take up a lot less space per person than cars.
Originally Posted by subego View Post
The safest design seems to be a “protected” bike lane, where the bike lane is between the sidewalk and parked cars instead of parked cars and the street.
Yes. Here in Sendai, the “bike lane” that I am supposed to use is a complete joke: half of it is on the side walk, the other on the sidewalk, and in the middle it is riddled with utility poles, sign posts, trees and the like.
Originally Posted by subego View Post
The only problem I can see with it is I’m sure there’s a much higher incidence of cyclists getting “doored”, since passengers don’t have any experience having to check for cyclists before opening the door.
In Groningen (The Netherlands), the bike lanes were in between parking spots and the sidewalk, but clearly separated from the sidewalk by either a barrier or being recessed. This eliminates the problem of dooring — and of a*holes parking on bike lanes.
Originally Posted by reader50 View Post
An example roundabout in a town nearby. This used to be a normal intersection of 4-lane roads. With signal lights. Some misguided person changed it to a 1-lane roundabout, and narrowed both roads to 2-lane, by giving both roads wide bike lanes. Which I have yet to see any bicycles in.
Sounds like a chicken-and-egg problem to me: you have to build the infrastructure first.
Originally Posted by reader50 View Post
There are cross walks, but no stop signs to protect pedestrians. Or buttons to push, for the missing signal lights to protect them.
Depending on the amount of traffic you get, you don't need traffic lights for pedestrians, just like a regular intersection with Stop signs does not need traffic lights for pedestrians to cross safely. By default I would expect the same traffic rules to hold as at intersections with stop signs: pedestrians have the right of way.
Originally Posted by reader50 View Post
Note the elevated whatsit in the center, blocking driver view across. When I first approached it after the downgrade, I thought the road was closed with a barrier. Driving across that could cause serious suspension damage. Now I just see the fail.
I think only few people would get confused and insist on plowing into the barrier.
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reader50
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Today, 01:25 AM
 
Street View image of the intersection before the downgrade. The side street was just as wide. Bike lanes were already present.



Has to be a deliberate choke point. 8 lanes of traffic (4 on each road) choked down to a 1-lane roundabout.

If the future really is bicycles, we'd better unload our Tesla stock while it's still worth something.
     
OreoCookie
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Today, 03:58 AM
 
Originally Posted by reader50 View Post
Street View image of the intersection before the downgrade. The side street was just as wide. Bike lanes were already present.
While I can't see how the bike lanes are routed through the roundabout, unprotected bike lanes on regular roads are semi-useful. Let's say, you want to take a left turn, then you first have to leave your semi protected zone and — fairly or not — you'd be considered an obstacle by most motorists.
Originally Posted by reader50 View Post
Has to be a deliberate choke point. 8 lanes of traffic (4 on each road) choked down to a 1-lane roundabout.
Slowing down traffic near the roundabout is part of the concept, yes. I do not know why in this specific instance this layout was chosen, there are roundabouts with more than one lane after all. But the studies I have linked to show that this improves safety for motorists and dramatically improves safety for non-motorists. Nevertheless, if done right, the roundabout will have roughly the same or better traffic flow than the old intersection. (Of course, that really depends on the details, i. e. the traffic patterns and such.)
Originally Posted by reader50 View Post
If the future really is bicycles, we'd better unload our Tesla stock while it's still worth something.
Follow Horace Dediu from Apple analyst fame, he is all about that these days. Many cities in Europe switch their transportation infrastructure from a car-centric system to a pedestrian-bicycle-public transportation-centric system. Bikes are the fastest mode of transportation for short(er) distances. Bike traffic has increased steadily in many parts of the world, but the planners of the transportation infrastructure have, by and large, not taken this into account.

IMHO self-driving cars and electric cars are for the majority of people useless gadgets. That is because most people live in urban centers, and cars are extremely inefficient at moving humans about. They are expensive, take up loads of space and spend most of their time doing nothing. Whether or not the car is self-driving doesn't change anything. I'd be poor if I had to buy and maintain a car. Even friends of mine who work for big German car companies have kept their cars until they essentially fell apart. (One of them did way more than 500,000 km.) In contrast, you can get a decent commuter bike for the price of the wheels or pain upgrade on your car. And for the price of two, three option packages on a BMW, I can probably get a pro-level road or mountain bike. Precisely because bikes are so much cheaper, the bike industry will never be as big as the car industry. But that's a feature, not a bug.

Just to be clear: if I were independently wealthy, I'm quite sure I'd own a car or two (Porsche 911 4S with a proper manual and a station wagon). I'm not against cars, because I hate cars, quite the contrary. Some are beautiful machines of art and just awesome. But on the list of priorities in my life — and the lives of many people I know, it is near the bottom. I know cars are a necessity for others, but the number of those people will decrease.
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reader50
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Today, 04:28 AM
 
Originally Posted by OreoCookie View Post
IMHO self-driving cars and electric cars are for the majority of people useless gadgets. That is because most people live in urban centers, and cars are extremely inefficient at moving humans about. They are expensive, take up loads of space and spend most of their time doing nothing.
Europe must not have our housing problems. Many people commute up to 100 miles to reach work each day.

I've read that ~70% of the Los Angeles area is zoned for single-family housing, and no one wants their neighborhood re-zoned for denser housing. ie - condominiums, apartments, etc. So when city housing density cannot increase, people live on average farther and farther away from their work. Telecommuting helps for some people. It would help more if we didn't have our overpriced and underspeed internet service, from the cable company monopolies.

Anyone who has a house is unlikely to sell it lightly (or cheaply), so it's difficult to find housing close to work. Hence all the multi-kilometer commuting.
     
Laminar
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Today, 01:29 PM
 
Originally Posted by OreoCookie View Post
Depending on the amount of traffic you get, you don't need traffic lights for pedestrians, just like a regular intersection with Stop signs does not need traffic lights for pedestrians to cross safely. By default I would expect the same traffic rules to hold as at intersections with stop signs: pedestrians have the right of way.
I hate to keep banging on this point but I feel like there's some sort of disconnect here.

Roundabouts are a benefit for traffic flow because, ideally, no car ever has to stop, so you don't get cars stopped at signs or lights, impeding the flow for no reason and wasting time.

Pedestrian crossings can ONLY happen safely when cars are stopped.

Traditional intersections require cars to stop, sometimes for no good reason. But built into that is a safe time for pedestrians to cross.

Roundabouts are designed so that, ideally, no one ever stops, so there's never a built-in safe time for pedestrians to cross.

With a roundabout, traffic doesn't stop due to a road sign or light. Cars have to specifically recognize a pedestrian waiting to cross, and they have to make the specific choice to stop for the pedestrian, and 99.99% of the time there's no downside to not stopping for a waiting pedestrian - "Let someone else stop for them, I'm busy and important and need to get home so I can kick my dog."

Plus the cars are likely looking for a gap in the traffic in the roundabout, not for one person patiently waiting to cross on the side of the road. It's a system that relies on the attentiveness and goodwill of the average driver, which is not a safe bet.
     
 
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