Roundabouts

[KeithW]

Other than people changing lanes across, or almost into, me, the only problem I have had on roundabouts is where people at a junction do see me, yet think they have enough time to race on in front of me.

I certainly have a greater fear of people racing to the roundabout then making an instant decision to go for it before I reach them, or being behind someone who has to slam the brakes on because they feel they misjudged it,than I do worrying someone behind me will not stop because I was forced to slow down on approach.

I fail to understand the argument that allowing people to approach faster, and consequently have less time to think, will improve safety.

The car on the A68 roundabout may have been going at a high speed, but because of the visibility the safe speed as only as far as they can see. Aside from the possibility of an obstruction on it, they also know that as they cannot see other traffic, other traffic can not see them so will join the roundabout. Which safety aside, actually is more efficient as it keeps traffic flowing.

Clear the centre of the roundabout and that driver will now think as it can be seen it is safer to go much faster as anyone approaching can wait. And approaching traffic may misjudge the speed, or think that because they can be seen it is safe to go charging on regardless, which already happens far too often in my experience.

Please note that I have NOT suggested that allowing people to approach faster is a good thing. What I have said is that when a driver reaches the give way line he/she should have the best possible visibility. There are roundabouts where visibilty is deliberately restricted on the approach but at the give way sign is clear. This is perfectly sensible. In the example I gave the opposite is true. Hang back 50 metres and you can see approaching traffic. At the give way line you cannot.

You seem to be suggesting that its better that a driver on the A68 be unable to see approaching traffic and that the approaching traffic should be unable to see him. This is not a view I can agree with I am afraid. I prefer not to take part in a lottery where the only prize is avoiding serious injury. The simple fact is that people on such roundabouts DO go too fast every day on the basis that they have the right of way.

There is an old saying in the English language 'Out of Sight Out of Mind' that unfortunately is how all too many drivers behave.

[someone]

You seem to be suggesting that its better that a driver on the A68 be unable to see approaching traffic and that the approaching traffic should be unable to see him.

Goodness knows how you got that idea from what I said, although if you think the current A68 roundabout is configured that way then I would question if you can see the required 20 metres to hold a licence. There is enough visibility to to see the traffic which is approaching you, whether on the roundabout or at the junction, whilst ensuring both travel at a speed that is appropriate for safety. If the problem with that roundabout is people going too fast on it, then action should be taken. Enabling people to go even faster will not make it safer.

If you give full visibility across the roundabout people will approach faster. You may disagree that that is what you want, but it is what will happen. And is also what you said you want: "slowing down to walking pace or less is not always desirable." If they see you approaching they will go faster because they will think they are seen and you will stop. And people on approach will see the roundabout is not busy, decide from much farther out they can drive straight on, and not slow down enough,.

Today I had two people pull out on me on smaller roundabouts on the A22 (one was either the B2028 or A25 one, the other at the urban one at Whyteleafe). Because of their sizes they had nothing in the middle so offered perfect visibility across them. It also meant the distance between us was so short that I had to brake to quickly lose speed. It is a too common occurrence for me to put speed over my safety.

The car on the A68 GSV was far enough away that had you pulled out it when it appear then at worst it would have been able to safely lose speed by just come off the accelerator, but should have been travelling at an appropriate speed to allow you to join as it was approaching an unseen junction.

You should not need to see the other side of the roundabout, or even the previous junction if the roundabout is large enough. If you do then you are going too fast.

[KeithW]

You seem to be suggesting that its better that a driver on the A68 be unable to see approaching traffic and that the approaching traffic should be unable to see him.

Goodness knows how you got that idea from what I said, although if you think the current A68 roundabout is configured that way then I would question if you can see the required 20 metres to hold a licence. There is enough visibility to to see the traffic which is approaching you, whether on the roundabout or at the junction, whilst ensuring both travel at a speed that is appropriate for safety. If the problem with that roundabout is people going too fast on it, then action should be taken. Enabling people to go even faster will not make it safer.

If you give full visibility across the roundabout people will approach faster. You may disagree that that is what you want, but it is what will happen. And is also what you said you want: "slowing down to walking pace or less is not always desirable." If they see you approaching they will go faster because they will think they are seen and you will stop. And people on approach will see the roundabout is not busy, decide from much farther out they can drive straight on, and not slow down enough,.

Today I had two people pull out on me on smaller roundabouts on the A22 (one was either the B2028 or A25 one, the other at the urban one at Whyteleafe). Because of their sizes they had nothing in the middle so offered perfect visibility across them. It also meant the distance between us was so short that I had to brake to quickly lose speed. It is a too common occurrence for me to put speed over my safety.

The car on the A68 GSV was far enough away that had you pulled out it when it appear then at worst it would have been able to safely lose speed by just come off the accelerator, but should have been travelling at an appropriate speed to allow you to join as it was approaching an unseen junction.

You should not need to see the other side of the roundabout, or even the previous junction if the roundabout is large enough. If you do then you are going too fast.

I would suggest that going ad hominem is hardly helpful. This is a junction I know well and in my opinion it IS dangerous as currently configured precisely because people coming down the A68 in practice hang back well short of the give way line to spot a gap and then go for it. This is indeed a bad idea.

To address your points in detail

If they see you approaching they will go faster because they will think they are seen and you will stop. And people on approach will see the roundabout is not busy, decide from much farther out they can drive straight on, and not slow down enough,.

If they can see me and I can see them I will indeed stop, I am required to give way after all. The problem arises AFTER I have stopped and now no longer have a clear view of approaching traffic nor can they see me. My point is simple. From the give way line I have insufficient time to safely see any approaching traffic and judge its speed and decide if its likely to leave at the next exit. From the apex of the corner to the stop line is less than 40 metres. A car at 30 mph is covering 13 metres per second , at 40 its 17 metres per second so you have a little over 2 seconds. Now I agree that the driver on the roundabout SHOULD drive more slowly, the reality is that, shock horror, many people drive too fast and fail to use their indicators.

Hang back on the approach which most local drivers do and you now have 60-90 metres of visibility and 5 seconds.
Observation will show that drivers slow down here where they can see approaching traffic and if its clear they gun it.

https://www.google.co.uk/maps/@54.55715 ... authuser=0

Now I am NOT saying that this is desirable as I agree entering a roundabout at high speed is a bad idea.

Cut back the foliage on the roundabout AND screen the view from the approach down the A68 with a hedge or fence along the centre and you have a situation where I and any oncoming traffic have 5 seconds decision time and as I cannot see approaching traffic from a distance I am more likely to slow to a walking pace or less on the approach. Having stopped however there is now adequate visibility for both traffic on the roundabout and A68 to see and be seen.

There is a secondary reason for wanting to cut back the herbage on the roundabout. In 2016 a driver lost it there and his car crashed through the foliage and remained unseen wrapped around a tree in the middle of the roundabout with his body inside for a week.
https://www.mirror.co.uk/news/uk-news/b ... ed-9603974

I would suggest that something is wrong when a wrecked car and dead man in the middle of a roundabout could not be seen.

[Owain]

It’s well-established that you should slow down on the approach to a junction. Many junctions would have been fine to straight-line years ago but now are too busy to do so without inconveniencing those around you.

The tall fences are irritating because they force you to think, and drivers generally don’t like that.

No, they’re irritating, not because they force you to think, but because they prevent you from observing properly (what you’re supposed to do) unless you jam the brakes on so hard, you practically have to stop and give way.

I have to agree with Berk on this one. I always think when I'm driving, about my driving.

The barriers don't force you to stop. They don't even force anybody to give way, if they don't want to. What they do is force you to slow down to a near-stop, often quite unnecessarily. This costs those of us who are good at using roundabouts in a sensible and considerate manner in time, fuel, and brake pads/discs.

They also make cyclists harder to spot.

[Berk]

This. It’s almost impossible to see a cyclist through baffle boards.

Nothing more needs to be said.

(Just as a point of order, if highway policies meant that ‘give way’ at roundabouts was being changed to ‘stop and give way’, wouldn’t all those dotted lines need to be replaced with solid ones??)

[AndyB]

It’s well-established that you should slow down on the approach to a junction. Many junctions would have been fine to straight-line years ago but now are too busy to do so without inconveniencing those around you.

The tall fences are irritating because they force you to think, and drivers generally don’t like that.

No, they’re irritating, not because they force you to think, but because they prevent you from observing properly (what you’re supposed to do) unless you jam the brakes on so hard, you practically have to stop and give way.

I have to agree with Berk on this one. I always think when I'm driving, about my driving.

The barriers don't force you to stop. They don't even force anybody to give way, if they don't want to. What they do is force you to slow down to a near-stop, often quite unnecessarily. This costs those of us who are good at using roundabouts in a sensible and considerate manner in time, fuel, and brake pads/discs.

They also make cyclists harder to spot.

My problem here is the "jamming the brakes on so hard" bit. Approaching that roundabout, you can see the foliage on the roundabout, specifically how wide it is. It's a fairly reasonable guess that foliage will be (more or less) evenly spread, limiting your view on final approach, especially given the inevitability of exit flags, so why approach at speed and waste fuel and brakes?

The cyclist thing I don't really buy. If you have 5-6 seconds advance view of the roundabout, you will see cyclists in advance and will know to make sure they have passed safely. If there's a high fence down the central reservation, you're not going to see much of anything anyway until you get a lot closer to the roundabout, and should slow down anyway.

[Owain]

It’s well-established that you should slow down on the approach to a junction. Many junctions would have been fine to straight-line years ago but now are too busy to do so without inconveniencing those around you.

The tall fences are irritating because they force you to think, and drivers generally don’t like that.

No, they’re irritating, not because they force you to think, but because they prevent you from observing properly (what you’re supposed to do) unless you jam the brakes on so hard, you practically have to stop and give way.

I have to agree with Berk on this one. I always think when I'm driving, about my driving.

The barriers don't force you to stop. They don't even force anybody to give way, if they don't want to. What they do is force you to slow down to a near-stop, often quite unnecessarily. This costs those of us who are good at using roundabouts in a sensible and considerate manner in time, fuel, and brake pads/discs.

They also make cyclists harder to spot.

My problem here is the "jamming the brakes on so hard" bit. Approaching that roundabout, you can see the foliage on the roundabout, specifically how wide it is. It's a fairly reasonable guess that foliage will be (more or less) evenly spread, limiting your view on final approach, especially given the inevitability of exit flags, so why approach at speed and waste fuel and brakes?

The cyclist thing I don't really buy. If you have 5-6 seconds advance view of the roundabout, you will see cyclists in advance and will know to make sure they have passed safely. If there's a high fence down the central reservation, you're not going to see much of anything anyway until you get a lot closer to the roundabout, and should slow down anyway.

On a roundabout without baffle boards, you get an excellent view of traffic on the roundabout if there is no foliage and if the grass is cut short; at some, like this one, you can even get a good view of traffic that might be joining the roundabout from other roads as you approach, well before you arrive at the give way lines. Obviously if there is foliage, or if the council have allowed the grass to grow high (as sometimes happens on the example I've used), your visibility is reduced so it makes sense to exercise a greater level of caution on approach than when there is no foliage or when the grass is short!

As for cyclists, the problem with the baffle boards as used quite widely now in England (I can't remember encountering any in Northern Ireland), is that they don't allow you anything close to 5-6 seconds of observation time. Instead, they prevent you from seeing onto the roundabout until you are a car's length from the give way line. This means that you need to look for cars and cyclists at the same time. Many people will automatically look for cars and trucks, and will forget that there might be a cyclist close to the outer edge of the roundabout, and therefore even more likely to be obscured by the boards until the driver entering the roundabout is right at the line.

[Berk]

My recollection of Northampton is that you get about 2 seconds advance view before you hit the roundabout. That’s a massive reduction - I usually expect to get at least 10-15 seconds.

As for having to tailor my approach speed to the prevailing conditions - fine if those conditions include heavy traffic or bad weather.

But otherwise you’re asking for folks to approach roundabouts at 10mph or less. Remember, some folks only feel comfortable taking the roundabout itself at that speed.

Spread that congestion back, and you’d be looking at multi-mile queues like the A1.

[jgharston]

Twice in the last two days I've approached the same roundabout thinking to myself "give way to the right, give way to the right", and seeing somebody approaching the entrance to my right I have slowed to a stop - only for them to also slow to a stop, and the person approaching at my left also stopping giving way to me - but I've given way to the chap to my right who seems to have given way to me on their left. We then all sit there wondering who's going to break the deadlock and inch forwards.

[Berk]

Ugh. It’s just as bad on roads with pinch points, or narrow bridges. Is teaching some drivers how to play chicken part of their training??

Wasn’t part of mine.

[Bryn666]

Ugh. It’s just as bad on roads with pinch points, or narrow bridges. Is teaching some drivers how to play chicken part of their training??

Wasn’t part of mine.

Given that most pinch points are:

(a) signed with distinct priority measures
or
(b) hundreds of years old

The former you have no legal basis to play chicken, if your sign has the mandatory give way you do that. The latter, well, it's called give and take. You slow down and see what the other vehicle is doing before making a decision.

Nowhere on the road network requires you to play chicken - even the old suicide lanes were optional to use.

[Bryn666]

Here's a sketch showing how US geometry principles would look applied to driving on the left.

Notice that each entry has a two stage speed reduction using a tangent instead of a perpendicular entry with a radius which does not slow traffic down sufficiently before entering.

[Fenlander]

Approaching a roundabout yesterday from an unusual direction for me I realised why I see so much confusion and cutting up on it. There's now a big yellow board on the left saying GET IN LANE AHEAD right at the point the road widens to 2 lanes but the sign itself obscures the board showing which lane goes where until you're past the decision point. It's also a 5 armed roundabout where straight on is confusing - turning off to the A16 is ahead and left, staying on the A17 is ahead and right and a right turn on to the A16 is a hairpin turn. Only 1 lane is marked as straight on and it gets the biggest queue as it serves 3 of the 4 exits.
It's bad enough putting the lane guidance too late, made worse by it being unclear and then even more worse by blocking the view of it with a sign telling you to look at the sign it's blocking!

[Berk]

Ugh. It’s just as bad on roads with pinch points, or narrow bridges. Is teaching some drivers how to play chicken part of their training??

Wasn’t part of mine.

Given that most pinch points are:

(a) signed with distinct priority measures
or
(b) hundreds of years old

The former you have no legal basis to play chicken, if your sign has the mandatory give way you do that. The latter, well, it's called give and take. You slow down and see what the other vehicle is doing before making a decision.

Nowhere on the road network requires you to play chicken - even the old suicide lanes were optional to use.

I agree with you - it shouldn’t need to happen.

Sadly, my experience is that some drivers give way twice - when it’s their turn to do so (at the sign), and when it isn’t.

Must be like a sort of... fail-safe?? For them, anyway.

[Fenlander]

Twice in the last two days I've approached the same roundabout thinking to myself "give way to the right, give way to the right", and seeing somebody approaching the entrance to my right I have slowed to a stop - only for them to also slow to a stop, and the person approaching at my left also stopping giving way to me - but I've given way to the chap to my right who seems to have given way to me on their left. We then all sit there wondering who's going to break the deadlock and inch forwards.

You get that a lot here. Approaching this way you can easily see traffic approaching from the right and you duly stop and give way to them, equally you can also see traffic approaching from the left knowing they should be giving way to you. The road from the right however has an entirely different view of the roundabout, they can easily see you giving way to them but their view to the right is non-existent until they get to the give way line. Traffic coming from the left then gets confused as they see you stop but can't see why so they either stop as well while they work it out, which creates a reason to stop for the unsighted minor road driver resulting in all 3 staring at each other wondering who will go first.
The usual thing that happens is that streetview driver stops as they can see someone coming up from the right & left. The car from the left sees streetview car stopping for them but can't see to their right due to the scenery so they too slow & stop, streetview car is then cursing at this point at they could have gone (out of turn) if they knew this was going to happen. Car 3 then arrives on the scene (from streetview's left) and sails straight through the roundabout without slowing or stopping. Car 1 takes advantage of this to pull away, car 2 is then snookered as car 3 is usually at the head of a queue from their preceding traffic lights and has to wait for all them, more car 1s appear and stop (give way to traffic on roundabout & car 2 that is waiting to the right), all the car 3s have gone to car 2 pulls onto roundabout only for the new car 1s to drive straight into the side of them as apparently no one ever expects anyone to turn right at that roundabout.
I go through that roundabout several times a day and the amount of times I see it is crazy, and you can see it all unfold from the streetview position due to the good sightlines. In reality it's reverted back to the previous normal T-junction give way priorities due to the sightline limitation but with the sometimes ignored roundabout priorities thrown in too. The bold sail on in and rely on priority to clear a path, most stop and give way only to then be delayed by the bold, add in a wrong side right-turner and you get conflict, the non-indicating left turners force people to stop and give way to ghosts.

[Berk]

Here's a sketch showing how US geometry principles would look applied to driving on the left.

Notice that each entry has a two stage speed reduction using a tangent instead of a perpendicular entry with a radius which does not slow traffic down sufficiently before entering.

That roundabout design is interesting. I’ve seen similar examples in Spain (exactly like the American version).

The ones I’ve seen over here are similar, but with a little less geometry. Glinton is one example, another is the new one on the B1174 just outside Grantham.

At least I can now see why the offset has been introduced.

[Bryn666]

Here's a sketch showing how US geometry principles would look applied to driving on the left.

Notice that each entry has a two stage speed reduction using a tangent instead of a perpendicular entry with a radius which does not slow traffic down sufficiently before entering.

That roundabout design is interesting. I’ve seen similar examples in Spain (exactly like the American version).

The ones I’ve seen over here are similar, but with a little less geometry. Glinton is one example, another is the new one on the B1174 just outside Grantham.

At least I can now see why the offset has been introduced.

The fundamental point with these is if you don't have the two stage speed reduction, they don't work properly.

We don't build the two stage speed reduction because "land costs money", therefore we put in a super tight deflection on a straight approach meaning overshoot, entry path overlap, and rollover incidents are increased.

If you can't offset you need to provide the Dutch style:

http://irishcycle.com/wp-content/upload ... dabout.png

[Peter Freeman]

Australia builds its roundabouts (most new ones that have the space, anyway) with a right then left bend in each approach, and often much more emphatic than in your image. They work.

I still really appreciate roundabout junctions, where appropriate, but I believe that their best attributes are only realised when operating at low speeds. The lower, the better. Unfortunately, for many drivers they don't work well or safely, owing to haste and impatience. Poor geometry, and especially over-large radiuses on both approach and circulatory carriageways, seems to accommodate or even encourage that impatience and makes matters worse.

[Bryn666]

Exactly Peter.

Most modern roundabout guidance expects the design to limit things to a maximum of 40km/h. Roundabouts, even in rural areas, need to be low speed. Once you have multiple entries and a huge circulatory, you're looking at needing signal control to keep the speeds at a sensible level otherwise what you've actually built is a rotary with merging and weaving.

The crucial element of modern roundabout design is paths cross - they don't merge. Any design that deviates from that will not work as intended and speeds will be high, gaps short, and congestion will be worse caused by a mix of impatience and hesitation.

It's also why two bridge roundabouts have fallen out of favour in many places.

[Bryn666]

The other thing is there are variations of roundabout that should be applied where appropriate:

The geometry Peter and I refer to is applicable for roundabouts between two single carriageways, or a dual and a single. It has at-grade NMU facilities.

If you cross two dual carriageways, the turbo roundabout is probably a better solution. Segregate NMUs with this design as it is a faster throughput of traffic: https://photorator.com/photo/83654/turb ... therlands-