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Simple roundabouts are definitely good but in UK I have found spiral roundabouts error prone if you have not driven on it before Example: [1] When visiting for

Simple roundabouts are definitely good but in UK I have found spiral roundabouts error prone if you have not driven on it before Example: [1] When visiting for the first time on a specific spiral roundabout: 1. Lane markings are faded 2. You do not know the specific lane unless you come very close to it and have to make a quick decision 3. Often due to queued traffic you cannot even see the lane marking until its too late. Because of this I have seen people change lanes on a roundabout because they made a mistake and its dangerous. [1] https://www.google.com/maps/place/Sainsbury's/@51.5080462,-0.5816409,173m/data=!3m2!1e3!5s0x48767ab1f69dfbc7:0x480bc3e7f0621fd4!4m6!3m5!1s0x487664d7ccdb3e33:0xdc0fd0ed013eb0d1!8m2!3d51.5080945!4d-0.579077!16s%2Fg%2F1ptvv67nn?entry=ttu https://www.google.com/maps/place/Sainsbury's/@51.5080462,-0...

ikekkdcjkfke 3y ago
If youre going more than half way around you want to go on the inner
throw0101a 3y ago
"Spiral Roundabouts | Understanding what to do": * https://www.youtube.com/watch?v=e6TsX9Ob91w https://www.youtube.com/watch?v=e6TsX9Ob91w I'm more curious about the straight-through path of [1] above.
- devnull3 3y ago
  There is a sign board which tells whether to take the middle road or left [1] This is the round-about layout [2] None of the above tell the precise lane to take. Only when you enter the roundabout you will know. See.[3]. Imagine cars waiting on these markings. This is what frustrates me the most. [1] https://www.google.com/maps/@51.5066257,-0.5789164,3a,75y,326.22h,95.34t/data=!3m6!1e1!3m4!1sITsslQOLf6wfrkVJAGWzvA!2e0!7i16384!8i8192?entry=ttu https://www.google.com/maps/@51.5066257,-0.5789164,3a,75y,32... [2] https://www.google.com/maps/@51.506316,-0.5784722,3a,37.5y,294.41h,93.18t/data=!3m6!1e1!3m4!1s3g-q9_qQvfAXgaCI7q8YeA!2e0!7i16384!8i8192?entry=ttu https://www.google.com/maps/@51.506316,-0.5784722,3a,37.5y,2... [3] https://www.google.com/maps/@51.5076664,-0.5804344,3a,75y,296.87h,79.1t/data=!3m6!1e1!3m4!1sLYadgZBR4tZKY1tp7KZtBQ!2e0!7i16384!8i8192?entry=ttu https://www.google.com/maps/@51.5076664,-0.5804344,3a,75y,29...
  - throw0101a 3y ago
    I meant how the straight-through part deals with yielding and such, but I see that it is (like) a signalled/lighted intersection.
  - fy20 3y ago
    My city has a lot of large roundabouts and a few years ago they made big improvements that reduced the number of incidents and improved traffic flow: 1. They switched from 3 lane traditional to 2 lane spiral roundabouts. There are signs well before you enter the roundabout telling you what lane you need to be in, so you can get into the right lane early. We have a lot of snow in winter, so road markings are not visible. Example of a sign indicating which lane you need to be in. After this sign, there are two more signs indicating lanes before you get to the roundabout - the next has destination names. https://maps.app.goo.gl/zJLaFC78i232mUkh6 https://maps.app.goo.gl/zJLaFC78i232mUkh6 2. The lanes on the roundabouts have solid white lines which you must not cross. You can only cross lanes to go more towards the center. I'm surprised, but people actually follow this rule. Example of lanes (and a rare sight of police...) https://maps.app.goo.gl/HbnkXYkacX3dfq4j6 https://maps.app.goo.gl/HbnkXYkacX3dfq4j6 3. They added speed bumps on the roundabout. This slows down the traffic on the roundabout, giving more chance for vehicles to enter. https://maps.app.goo.gl/fMKBjocYAFTmpE6ZA https://maps.app.goo.gl/fMKBjocYAFTmpE6ZA
Enginerrrd 3y ago
Transportation engineer here: Multi-lane roundabouts don't typically have any safety benefits. Single lane roundabouts do. Also, on the small side where you have traffic circles rather than roundabouts, those also suck.
- kmeisthax 3y ago
  wait I thought "traffic circle" and "roundabout" were synonyms
  - RandallBrown 3y ago
    They are in most contexts. There are "traffic circles" that aren't roundabouts but just a round block in the middle of an intersection that requires the traffic to move around in a circle so cross traffic is slowed. Also called a "traffic calming circle." https://www.seattle.gov/transportation/projects-and-programs/safety-first/traffic-operations/traffic-circles https://www.seattle.gov/transportation/projects-and-programs... That could also be a location specific term too. These circles are very common in Seattle.
    - lotsofpulp 3y ago
      I thought that was a roundabout. At least my UK family would call that a roundabout.
      - patja 3y ago
        Roundabouts have to have splitters and other features that traffic calming circles lack. Also, technically you can go whichever way you want around a traffic calming circle: counterclockwise is recommended, but many trucks physically cannot navigate them that way. And there are zero traffic laws distinguishing a traffic calming circle from an uncontrolled intersection.
  - j16sdiz 3y ago
    Depends on which country/state you are from, they may or may not be the same. Look up on wikiprdia, there are even different types of roundabouts
globular-toast 3y ago
This is a problem with all multi-lane layouts and exacerbated by drivers' behaviour. The problem is road users new to the road do not know which lane to be in already and they are pressured to go fast. The instant it looks like they've chosen a lane, a driver from behind who is familiar with the layout closes the gap in the other lane, trapping them. This can be mitigated a bit by the first user having the confidence to slow down and straddle lanes until they are sure of the correct lane, but it's surprising how quickly such opportunities are missed. The real problem is familiarity with lane layouts allows the road to operate at far higher capacity then normally possible and with less maintenance. They are squeezed to their limits in morning rush hours comprised of mostly familiar users. You'll even see users observing essentially invisible road markings because they're doing it from memory. No chance of you're unfamiliar with the road. Roads start to fail way before 100% capacity, but these lane markings allow that to be squeezed further during rush hours.
- sfn42 3y ago
  It's not a big problem to be in the wrong lane. You just change lanes like any other road. And like any other road, when you change lanes, it's your responsibility to make sure the lane you're merging into has space for you.
  - devnull3 3y ago
    Driving schools in UK teach that changing lanes on a roundabout is unsafe. Infact, in a driving test doing so will result into a failure because most people will not follow safety checks and signalling. If you are in a wrong lane, the safest thing is to continue on it, exit the roundabout and comeback again or go around the roundabout.
    - sfn42 3y ago
      You can't exit from the inner lane without changing lanes.
  - globular-toast 3y ago
    Perhaps you've never driven so I'll give you the benefit of the doubt. Cars can't move sideways. To change lane you have to go forwards. There is no "just change lane". Of course you could just not change lane, to the wrong way and safely correct your course later. This is preferable but people tend to get stressed out in those situations which is also bad for safety. Not to mention that a safe but ineffective road hasn't really achieved much.
gvurrdon 3y ago
This one is particularly bad for lane changing: https://www.google.com/maps/@51.7874467,-1.278506,17.57z?entry=ttu https://www.google.com/maps/@51.7874467,-1.278506,17.57z?ent... Coming out of Oxford on the A4144 there are two lanes; the left lane is for taking the first two turns and the right lane for the remaining three. But, drivers unfamiliar with the layout who haven't seen the markings, or who fancy jumping the queue, will sometimes use the left hand lane to go straight ahead onto the A44. There's a similar situation coming from the A40 to the East. I've seen a few accidents there and even been involved in one as a result of this (someone tried to undertake me at speed as I exited, and caused a collision, 100% their fault according to our insurers).
- devnull3 3y ago
  Yeah, I never understood why the lane markings are not above the head and in advance instead of on the road. > drivers unfamiliar with the layout People familiar with the layout drive even when the markings are completely faded. It causes lot of anxiety if you are not familiar. It happened to me once where I was in a wrong lane. I continued on it as it was the most safest thing to do but the next exit was onto a motorway :). I was so angry with myself.
- jfk13 3y ago
  That Oxford example, at least, does have a "get in lane" sign[1] as you approach up the Woodstock Road, so any driver intending to go straight ahead on the A44 should know to use the right-hand lane to enter the roundabout. But of course not everyone notices every sign (and some drivers just wilfully disobey them if they think it'll save a few seconds...) [1] https://www.google.com/maps/@51.787062,-1.2794264,3a,15y,317.12h,92.61t/data=!3m6!1e1!3m4!1ssqjNPfx6xDqfCh0TcTQgZA!2e0!7i16384!8i8192?entry=ttu https://www.google.com/maps/@51.787062,-1.2794264,3a,15y,317...

ikekkdcjkfke 3y ago

If youre going more than half way around you want to go on the inner

throw0101a 3y ago

"Spiral Roundabouts | Understanding what to do": * https://www.youtube.com/watch?v=e6TsX9Ob91w https://www.youtube.com/watch?v=e6TsX9Ob91w I'm more curious about the straight-through path of [1] above.

devnull3 3y ago
There is a sign board which tells whether to take the middle road or left [1] This is the round-about layout [2] None of the above tell the precise lane to take. Only when you enter the roundabout you will know. See.[3]. Imagine cars waiting on these markings. This is what frustrates me the most. [1] https://www.google.com/maps/@51.5066257,-0.5789164,3a,75y,326.22h,95.34t/data=!3m6!1e1!3m4!1sITsslQOLf6wfrkVJAGWzvA!2e0!7i16384!8i8192?entry=ttu https://www.google.com/maps/@51.5066257,-0.5789164,3a,75y,32... [2] https://www.google.com/maps/@51.506316,-0.5784722,3a,37.5y,294.41h,93.18t/data=!3m6!1e1!3m4!1s3g-q9_qQvfAXgaCI7q8YeA!2e0!7i16384!8i8192?entry=ttu https://www.google.com/maps/@51.506316,-0.5784722,3a,37.5y,2... [3] https://www.google.com/maps/@51.5076664,-0.5804344,3a,75y,296.87h,79.1t/data=!3m6!1e1!3m4!1sLYadgZBR4tZKY1tp7KZtBQ!2e0!7i16384!8i8192?entry=ttu https://www.google.com/maps/@51.5076664,-0.5804344,3a,75y,29...
- throw0101a 3y ago
  I meant how the straight-through part deals with yielding and such, but I see that it is (like) a signalled/lighted intersection.
- fy20 3y ago
  My city has a lot of large roundabouts and a few years ago they made big improvements that reduced the number of incidents and improved traffic flow: 1. They switched from 3 lane traditional to 2 lane spiral roundabouts. There are signs well before you enter the roundabout telling you what lane you need to be in, so you can get into the right lane early. We have a lot of snow in winter, so road markings are not visible. Example of a sign indicating which lane you need to be in. After this sign, there are two more signs indicating lanes before you get to the roundabout - the next has destination names. https://maps.app.goo.gl/zJLaFC78i232mUkh6 https://maps.app.goo.gl/zJLaFC78i232mUkh6 2. The lanes on the roundabouts have solid white lines which you must not cross. You can only cross lanes to go more towards the center. I'm surprised, but people actually follow this rule. Example of lanes (and a rare sight of police...) https://maps.app.goo.gl/HbnkXYkacX3dfq4j6 https://maps.app.goo.gl/HbnkXYkacX3dfq4j6 3. They added speed bumps on the roundabout. This slows down the traffic on the roundabout, giving more chance for vehicles to enter. https://maps.app.goo.gl/fMKBjocYAFTmpE6ZA https://maps.app.goo.gl/fMKBjocYAFTmpE6ZA

Enginerrrd 3y ago

Transportation engineer here: Multi-lane roundabouts don't typically have any safety benefits. Single lane roundabouts do. Also, on the small side where you have traffic circles rather than roundabouts, those also suck.

kmeisthax 3y ago
wait I thought "traffic circle" and "roundabout" were synonyms
- RandallBrown 3y ago
  They are in most contexts. There are "traffic circles" that aren't roundabouts but just a round block in the middle of an intersection that requires the traffic to move around in a circle so cross traffic is slowed. Also called a "traffic calming circle." https://www.seattle.gov/transportation/projects-and-programs/safety-first/traffic-operations/traffic-circles https://www.seattle.gov/transportation/projects-and-programs... That could also be a location specific term too. These circles are very common in Seattle.
  - lotsofpulp 3y ago
    I thought that was a roundabout. At least my UK family would call that a roundabout.
    - patja 3y ago
      Roundabouts have to have splitters and other features that traffic calming circles lack. Also, technically you can go whichever way you want around a traffic calming circle: counterclockwise is recommended, but many trucks physically cannot navigate them that way. And there are zero traffic laws distinguishing a traffic calming circle from an uncontrolled intersection.
- j16sdiz 3y ago
  Depends on which country/state you are from, they may or may not be the same. Look up on wikiprdia, there are even different types of roundabouts

globular-toast 3y ago

This is a problem with all multi-lane layouts and exacerbated by drivers' behaviour. The problem is road users new to the road do not know which lane to be in already and they are pressured to go fast. The instant it looks like they've chosen a lane, a driver from behind who is familiar with the layout closes the gap in the other lane, trapping them. This can be mitigated a bit by the first user having the confidence to slow down and straddle lanes until they are sure of the correct lane, but it's surprising how quickly such opportunities are missed. The real problem is familiarity with lane layouts allows the road to operate at far higher capacity then normally possible and with less maintenance. They are squeezed to their limits in morning rush hours comprised of mostly familiar users. You'll even see users observing essentially invisible road markings because they're doing it from memory. No chance of you're unfamiliar with the road. Roads start to fail way before 100% capacity, but these lane markings allow that to be squeezed further during rush hours.

sfn42 3y ago
It's not a big problem to be in the wrong lane. You just change lanes like any other road. And like any other road, when you change lanes, it's your responsibility to make sure the lane you're merging into has space for you.
- devnull3 3y ago
  Driving schools in UK teach that changing lanes on a roundabout is unsafe. Infact, in a driving test doing so will result into a failure because most people will not follow safety checks and signalling. If you are in a wrong lane, the safest thing is to continue on it, exit the roundabout and comeback again or go around the roundabout.
  - sfn42 3y ago
    You can't exit from the inner lane without changing lanes.
- globular-toast 3y ago
  Perhaps you've never driven so I'll give you the benefit of the doubt. Cars can't move sideways. To change lane you have to go forwards. There is no "just change lane". Of course you could just not change lane, to the wrong way and safely correct your course later. This is preferable but people tend to get stressed out in those situations which is also bad for safety. Not to mention that a safe but ineffective road hasn't really achieved much.

gvurrdon 3y ago

This one is particularly bad for lane changing: https://www.google.com/maps/@51.7874467,-1.278506,17.57z?entry=ttu https://www.google.com/maps/@51.7874467,-1.278506,17.57z?ent... Coming out of Oxford on the A4144 there are two lanes; the left lane is for taking the first two turns and the right lane for the remaining three. But, drivers unfamiliar with the layout who haven't seen the markings, or who fancy jumping the queue, will sometimes use the left hand lane to go straight ahead onto the A44. There's a similar situation coming from the A40 to the East. I've seen a few accidents there and even been involved in one as a result of this (someone tried to undertake me at speed as I exited, and caused a collision, 100% their fault according to our insurers).

devnull3 3y ago
Yeah, I never understood why the lane markings are not above the head and in advance instead of on the road. > drivers unfamiliar with the layout People familiar with the layout drive even when the markings are completely faded. It causes lot of anxiety if you are not familiar. It happened to me once where I was in a wrong lane. I continued on it as it was the most safest thing to do but the next exit was onto a motorway :). I was so angry with myself.
jfk13 3y ago
That Oxford example, at least, does have a "get in lane" sign[1] as you approach up the Woodstock Road, so any driver intending to go straight ahead on the A44 should know to use the right-hand lane to enter the roundabout. But of course not everyone notices every sign (and some drivers just wilfully disobey them if they think it'll save a few seconds...) [1] https://www.google.com/maps/@51.787062,-1.2794264,3a,15y,317.12h,92.61t/data=!3m6!1e1!3m4!1ssqjNPfx6xDqfCh0TcTQgZA!2e0!7i16384!8i8192?entry=ttu https://www.google.com/maps/@51.787062,-1.2794264,3a,15y,317...