2 lane approaches to single lane roundabouts: WHY???

highdef · 16-12-2013 04:02PM #1

Ok, there are dozens and dozens of these around the country. You approach a single lane roundabout but as you approach on the main road, it splits to 2 lanes.....just like this: http://goo.gl/maps/tA5EB - In this particular case, you can see that there is not enough room for 2 cars to safely travel on the roundabout, side by side. What would the correct procedure be here for both scenarios, taking 1st exit (left) or 2nd exit (straight ahead)?
As far as I know, unless otherwise stated, the left lane is for left or straight ahead and the right lane is for 3rd exit (or right, or anything more than 180 degrees around) but the right lane can be used for straight ahead if the exiting lane has 2 lanes present.
So going by the example I have posted, the left lane is for those going straight ahead or taking the left and the right lane is solely for anyone who wishes to make a turn back. Even if this is the case, 2 cars cannot be accommodated on the roundabout so this brings me back to my main query.....why 2 lanes???

foggy_lad · 16-12-2013 04:11PM

There is plenty of room on that roundabout for two cars or even two trucks to go around side by side, but if the cars or trucks are going to fast or do not keep to their side they will collide with other vehicles on the roundabout.

MarkR · 16-12-2013 04:20PM

You could fit two, once they are driving at an appropriate speed.

I do hate these types of roundabouts though.

corktina · 16-12-2013 04:34PM

that roundabout should have lane markings for the right lane to be straight ahead only and the left lane left turn only.

L1011 · 16-12-2013 05:56PM

Two cars can and do make it around that RAB from that direction.

highdef · 16-12-2013 05:57PM

corktina wrote: »

that roundabout should have lane markings for the right lane to be straight ahead only and the left lane left turn only.

Agreed, it "should" have them but it does not so therefore the standard rules apply which makes things awkward. Also, the fact that there is no lane division on the roundabout means that it is meant for only one line of cars at a time, not two. If 2 cars driving side by side at the roundabout collide, both will probably be to blame. If there were lane markings, at least someone will have been in the incorrect lane and can then get the blame.
I agree that at very low speed and with great co-operation with the adjacent car, 2 cars could travel side by side but in the real practical world, the current set up does not allow this. There are plenty of examples similar to this, some with even less space on the roundabout - http://goo.gl/maps/ynwhh

highdef · 16-12-2013 06:01PM

MYOB wrote: »

Two cars can and do make it around that RAB from that direction.

Would they both be going straight on (2nd exit)? If so, there is only one lane on the exit which means that technically, the person entering in the right lane will have been in the wrong lane. Am I correct?

L1011 · 16-12-2013 06:07PM

highdef wrote: »

Would they both be going straight on (2nd exit)? If so, there is only one lane on the exit which means that technically, the person entering in the right lane will have been in the wrong lane. Am I correct?

The second exit is more than 180 degrees (barely). What happens on the (rare) times there's any queuing there is that people going left use lane 1 and straight ahead use lane 1. That does involve two cars being on the RAB at once.

corktina · 16-12-2013 06:14PM

MYOB wrote: »

The second exit is more than 180 degrees (barely). What happens on the (rare) times there's any queuing there is that people going left use lane 1 and straight ahead use lane 1. That does involve two cars being on the RAB at once.

If you zoom out you'll see it is actually LESS than 180

L1011 · 16-12-2013 06:17PM

corktina wrote: »

If you zoom out you'll see it is actually LESS than 180

Entrance is splayed though. I think its on the mini map before as beyond 180 but can't remember (on mobile)

corktina · 16-12-2013 06:22PM

never mind the map, the photo shows clearly that it is NOT beyond 180 degrees

L1011 · 16-12-2013 06:25PM

It's beyond 180 from the flared entry point. That and the minimap sign before are all that can matter. You don't enter a roundabout straight on. The sign may or may not show, I can't check from here.

highdef · 16-12-2013 06:27PM

OK, fair enough, the 2nd exit may be a few degrees over 180 degrees. A technicality but that's the way it is! But it's very close if it is and some may disagree.

I guess my main qualm is what is the reason for having 2 lanes at the approach when it is not really needed, not just at this roundabout but at other of a similar set-up? With the main roundabout not being comfortably able to accommodate standard vehicles too well without good co-operation and a good knowledge of where your neighbouring driver is heading (the fact that there are not road marking to show 2 lanes further backs this up), I think having one lane split into 2 only to go immediately back to one on the roundabout is silly. Furthermore, the lack of direction arrows on the approach confuses drivers further as convention does not always correlate with the rules of the road in many cases such as the main example I gave.

The simplest solution would be to just leave it at one lane on the approaches. If two lanes are being kept for whatever reason, put direction arrows on the ground (like this example where the direction arrows are different to normal convention - left land, left only. Right lane, straight on only - http://goo.gl/maps/iNPQd) - simple and it works. In fairness, this is a much larger roundabout than other examples but it shows that a couple of direction indicators is not that difficult to put into place.

corktina · 16-12-2013 06:34PM

I believe you are looking at it from the wrong end....if you look at it with the side road to the left, as the photo shows and as the OP describes, it clearly is les than 180 degrees.

The Glass Key · 16-12-2013 06:41PM

What is wrong with people that they have to take up two lanes on a roundabout when there is room for two, the problem is not the roundabout its sloppy lazy driving. Correct use of indicators would help so anyone turning left should be indicating left from the approach direction indicated by the OP leaving anyone going straight ahead to use the right hand lane if they want to and stay on the inside of the roundabout.

Cienciano · 16-12-2013 06:48PM

Avoid Walkinstown, this is a disaster of a roundabout: http://goo.gl/maps/iXH3I

foggy_lad · 16-12-2013 07:14PM

highdef wrote: »

Agreed, it "should" have them but it does not so therefore the standard rules apply which makes things awkward. Also, the fact that there is no lane division on the roundabout means that it is meant for only one line of cars at a time, not two. If 2 cars driving side by side at the roundabout collide, both will probably be to blame. If there were lane markings, at least someone will have been in the incorrect lane and can then get the blame.
I agree that at very low speed and with great co-operation with the adjacent car, 2 cars could travel side by side but in the real practical world, the current set up does not allow this. There are plenty of examples similar to this, some with even less space on the roundabout - http://goo.gl/maps/ynwhh

Again there is plenty of room at that roundabout for two trucks to go around safely, Even without any road markings the road is clearly wide enough for two large vehicles or even two articulated trucks to negotiate the roundabout safely, there are no standard rules as you put it which would make it a single lane roundabout just because a driver can't keep to their own lane, The lack of lane division does not narrow the road.

foggy_lad · 16-12-2013 07:15PM

Cienciano wrote: »

Avoid Walkinstown, this is a disaster of a roundabout: http://goo.gl/maps/iXH3I

Approach it sober and awake and knowing where you want to go and where you are coming from and you shouldn't have any problems.

Iwannahurl · 17-12-2013 10:30PM

foggy_lad wrote: »

Approach it sober and awake and knowing where you want to go and where you are coming from and you shouldn't have any problems.

Yes, it's a tribute to Irish roads engineering, urban planning and traffic management.

_Kaiser_ · 17-12-2013 11:06PM

Whenever I come across one of these "2 lanes for 20m" type roundabouts where it's not clearly marked that the right lane is for right turns only, I will just straddle both.

I'm not going to risk being sideswiped because of nonsensical engineering

The Glass Key · 17-12-2013 11:13PM

Kaiser2000 wrote: »

Whenever I come across one of these "2 lanes for 20m" type roundabouts where it's not clearly marked that the right lane is for right turns only, I will just straddle both.

I'm not going to risk being sideswiped because of nonsensical engineering

Did I mention sloppy driving earlier? I think this is what I was talking about.

_Kaiser_ · 17-12-2013 11:28PM

The Glass Key wrote: »

Did I mention sloppy driving earlier? I think this is what I was talking about.

Have another look at the link in the OP - it's a single lane right up to the roundabout where it becomes 2 lanes, even though the roundabout itself and exits are again only really wide enough for single file traffic.

Given the amount of questions that are posted in the Motors forum about what lane to be in for various turns on a roundabout, you're damn right I won't take the chance of some idiot either drifting into the side of my car or cutting in front of me as they exit.

I'm not talking about doing so on a "proper" roundabout - just these pokey little ones like in the OP

Iwannahurl · 17-12-2013 11:43PM

Kaiser2000 wrote: »

Whenever I come across one of these "2 lanes for 20m" type roundabouts where it's not clearly marked that the right lane is for right turns only, I will just straddle both.

I'm not going to risk being sideswiped because of nonsensical engineering

It's bad enough in a car. On a bike it's potentially lethal. I frequently have motorists engaging in dodgy, and often outright illegal, manoeuvres in order to overtake on a roundabout.

Hilly Bill · 18-12-2013 01:21AM

foggy_lad wrote: »

Again there is plenty of room at that roundabout for two trucks to go around safely, Even without any road markings the road is clearly wide enough for two large vehicles or even two articulated trucks to negotiate the roundabout safely, there are no standard rules as you put it which would make it a single lane roundabout just because a driver can't keep to their own lane, The lack of lane division does not narrow the road.

There isnt a hope that you could get 2 trucks going around that side by side especially 2 artics.

highdef · 18-12-2013 02:57AM

Hilly Bill wrote: »

There isnt a hope that you could get 2 trucks going around that side by side especially 2 artics.

Agreed, I can't see this being done at all unless the drivers have practised the routine in advance. If there was room for two lanes, there would be lane divisions. If the legal widths are not there, the broken lines are not painted. It all about rules of the road!!!

Iwannahurl · 18-12-2013 12:23PM

highdef wrote: »

Agreed, I can't see this being done at all unless the drivers have practised the routine in advance. If there was room for two lanes, there would be lane divisions. If the legal widths are not there, the broken lines are not painted. It all about rules of the road!!!

What are the legal minimum lane widths on approach roads and on roundabouts?

I know of several examples in Galway where two or more roundabout entry lanes especially are crammed into a very small space.

bucketybuck · 18-12-2013 12:43PM

Roundabouts like those in the OP only exist for arseholes to skip a queue of traffic in the left lane by staying right, then cutting in front of another car and going straight ahead when on the roundabout itself.

beauf · 19-12-2013 01:54PM

Hilly Bill wrote: »

There isnt a hope that you could get 2 trucks going around that side by side especially 2 artics.

+1 and Buses coaches etc.

The Glass Key wrote: »

Did I mention sloppy driving earlier? I think this is what I was talking about.

Its not sloppy driving, its defensive driving and it prevents accidents. There's no need for two lanes. You only need two lanes (or multiple) where the roundabout is physically large enough for you do change lanes while on the roundabout. if you can't do that, then its entirely pointless having multiple lanes. If there was a left only filter lane, ok, but that should be before the roundabout not on it.

bucketybuck wrote: »

Roundabouts like those in the OP only exist for arseholes to skip a queue of traffic in the left lane by staying right, then cutting in front of another car and going straight ahead when on the roundabout itself.

Again exactly right. These layout just don't work. The roundabout is too small. They over engineer these things, for no good reason.

GTE · 20-12-2013 12:14AM

I know the roundabout the OP is on about well, I do remember being surprised that it was a double lane entry at one time. That said, it could take two cars but only close to the limit of being downright difficult, which is something I feel is wrong to tread close to when designing roads.

It annoys me also where there is a single lane into a double lane roundabout(not that it has to be a double in to a double by any means) but if there is space for two cars on entry, hardly anyone seems to pay attention to the road markings which grinds my gears.

Then moving on to where there is a double lane entry into a double lane roundabout, people just slash across the right hand lane. It is terrible around the Enfield roundabouts for instance.

Cuddlesworth · 22-12-2013 05:57PM

This would be a better example from my childhood, as evidenced by the 2-3 feet of mud on the inside edge. It would make far more sense to actually label the first lane as left hand turn only. You can put two cars around that roundabout, but introduce any large vehicle like a jeep or large van, combined with a member of the public placing their car to far forward while entering and you have a serious issue.

https://maps.google.ie/?ll=53.302641,-6.309097&spn=0.000652,0.001831&t=h&layer=c&cbll=53.302641,-6.309098&panoid=8pRJHt5yy5r26s-h-NC5tw&cbp=12,21.56,,0,15.4&z=20

beauf · 22-12-2013 06:12PM

That at least a bigger. Heres a much smaller one

http://tinyurl.com/oa7pkty

2 lane approaches to single lane roundabouts: WHY???

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