Unsafe roundabout design - North East

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mbeatts
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Unsafe roundabout design - North East

Post by mbeatts »

Some of you local to Gateshead have probably seen this absolutely crap new roundabout just up from Blaydon as per the below. Wasn't even open a week before the extra lanes were coned off as it was too unsafe :laugh:

Due to merge lanes being not long enough
roundabout.PNG
Last edited by mbeatts on Sun Jun 13, 2021 12:13, edited 1 time in total.
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JohnnyMo
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Re: Very strange roundabout design - North East

Post by JohnnyMo »

What is wrong? This looks a reasonably standard set up. Two lane exit and merge.
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Re: Very strange roundabout design - North East

Post by Beardy5632 »

Yes there's one in Ashington not far from where my extended family live. I've used it a few times when I've been up that way and never had an issue with it.

Not sure how that Blaydon roundabout is deemed unsafe as it looks fine to me. Are there people who are taking it too fast on there or something?
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trickstat
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Re: Unsafe roundabout design - North East

Post by trickstat »

Presumably there have been issues with traffic struggling to merge back into one lane coming away from the roundabout. However, I'm not sure how often people would actually be using the second lane when exiting? And, if they are, would there be anything in the nearside lane anyway?
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Re: Unsafe roundabout design - North East

Post by jervi »

Design looks fine tbh. Not too sure about the traffic islands on approach thou.
Maybe if it was repainted as a turbo roundabout it would be better?
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Re: Unsafe roundabout design - North East

Post by WHBM »

Looks OK to me too. You get a bit, but not a lot, of extra capacity from the 2-lane exit. I know that theoretically left-turners could be taking the nearside lane exit while oncoming right-turners could be taking the offside lane exit, to merge subsequently, but that doesn't happen in practice, as those right turners start to move towards the nearside while still negotiating the roundabout, and that in turn leads to (quite rightly) hesitance by left turners joining the roundabout. The formal Merge Left markings at the end of the offside lane exacerbates things. To get the capacity you need to cut a bit more off the SW and NE corners of that diagram and spiralise the markings to give a true left turn freeflow.

Is there much pedestrian crossing movement here ?
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Re: Unsafe roundabout design - North East

Post by B1040 »

So it looks like many roundabouts I have seen.
What's the issue?
Too much congestion ahead and traffic backing up preventing easy merges?
Too much traffic in lane 1 tailgating to prevent merges?
Traffic in lane 2 driving too fast and rear ending slower stuff after merging?
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Re: Unsafe roundabout design - North East

Post by M4Simon »

A quick look suggests to me that the design is very compromised and that they were struggling to achieve deflection requirements. It is, in my experience, very unusual to have a splitter island on the entry separating two lanes both going straight on, yet this happens on two out of four approaches. I know nothing about the context, but I would suggest the roundabout is too small for the traffic flow.

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Re: Unsafe roundabout design - North East

Post by mbeatts »

Here's a shot of what it used to be like, think one issue is a lot of people are used to sitting in the right hand lane coming from the east to go straight over but when the new bit opened, caused people to undertake in the new second left hand lane.

No foot traffic up here but does get very busy coming from south to east.
roundabout2 (1).jpg
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Re: Unsafe roundabout design - North East

Post by Piatkow »

As a stranger to the area I don't see a problem with the design as such. However looking at the "before" picture I can see that people would be used to L1 on the approach from the east being left turn only. The introduction of the subsidiary island between the two lanes reinforces this impression, especially if queuing traffic is covering the arrows on the road.
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Re: Unsafe roundabout design - North East

Post by 2 Sheds »

A similar but worse situation has been created in the last year north of Lincoln where the A 46 bypass meets the A15 at Riseholme. They spent millions upgrading it but haven’t done enough. So merging and diverging lengths are short, and some kerb lines where widened lengths tie in to the existing kerb lines have to be seen to be believed. Are transition curves taught on university courses these days ? Talk about spoiling the ship for a halfpennyworth of tar. If anyone can find an aerial view of it please post.
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Re: Unsafe roundabout design - North East

Post by Big Nick »

That looks much the same as this one in Harlow: https://www.google.co.uk/maps/@51.76434 ... a=!3m1!1e3

It took time to learn the new layout and people are still being confused as the lanes are not marked far ahead in advance so they arrive at the roundabout in the wrong lane.
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Re: Unsafe roundabout design - North East

Post by jabbaboy »

There's been a few crap roundabouts up here lately mind. That's always been a horrid roundabout though with left only turn which forces lorries etc into the overtaking lane.

This one at Blyth was the same, lasted about a month before there was a nasty accident - https://goo.gl/maps/ygWAPsVyCaC7ognt5

This one on what was a NSL dual carriageway is especially bad aswell and is far too tight hence the barriers constantly being wiped out - https://goo.gl/maps/s5HfBQsCNbtc5f686

Not to mention South Gosforth which is as bad as it's ever been which again is way too tight with rather confusing markings - https://goo.gl/maps/qZMQ5aLeYfkgH5fWA. Not a clue what's going on here - https://goo.gl/maps/tQss76W3KwqnMgod6
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Re: Unsafe roundabout design - North East

Post by M19 »

I remember using this road in the past. Coming for the east, it’s a long climb up from Blaydon with a crawler lane that ends at the roundabout. Too often dawdlers would place themselves in the right hand lane coming off the Blaydon roundabout a good mile or so before the junction rather moving into lane on the immediate approach. Hence it’s frustrating to those who wish to make quicker progress.

The problem with merge in turn at roundabouts though is that the design fails to take into account the reality driver behaviour. In the UK there’s a big problem with filtering - drivers get precious about being passed towards a merge in turn, which designs like this simply ignore. In fact more junctions these days seem to be designed to encourage road rage with short filtering section. The standards say yes but the reality suggests otherwise, yet the standards win out at the end of the day rather than understanding driver behaviour and designing out numtpiness.

The only redeeming feature of the roundabout is that it has splitter island between lanes to minimise entry path overlap, which is usually caused by awful entry angles.
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Re: Unsafe roundabout design - North East

Post by M4Simon »

Big Nick wrote: Sun Jun 13, 2021 19:54 That looks much the same as this one in Harlow: https://www.google.co.uk/maps/@51.76434 ... a=!3m1!1e3

It took time to learn the new layout and people are still being confused as the lanes are not marked far ahead in advance so they arrive at the roundabout in the wrong lane.
It really isn't the same. The one in Harlow is much bigger, and doesn't have the same lane configurations. Nor does it have the splitter islands separating the two ahead lanes like the one in the original post. Small changes in roundabout geometry can make a massive difference to road safety, and these two examples are very different.

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Re: Unsafe roundabout design - North East

Post by Bryn666 »

The faults should be quite obvious to us engineering types.

1. The kicker arrows on the exit lanes force the right hand lane to merge, but the kerb alignment actually forces the left hand lane to move right to continue. This is a conflict point straight off the bat.

2. The widths between the lane splitter islands look very tight to accommodate HGVs and I would not be surprised if overhang and wheel conflicts occur. Presumably it was tracked using the default 5 mph setting which would allow a HGV to fit down any ridiculously narrow gap with no consideration for real world driving styles.

3. The ICD itself does not lend itself to two lane circulation of the type shown, there will always be entry path overlap due to the incorrect design guidance DMRB offers in contradiction to what the rest of the world is now doing with roundabouts, where either perpendicular entries for low flow, low speed or smoother but more pronounced entry deflections for larger flow, higher speed junctions are preferred.

All in all, this looks like a complete waste of time and effort. Why did a Stage 1/2 safety audit not pick up any of these obvious faults?
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Re: Unsafe roundabout design - North East

Post by Peter Freeman »

WHBM wrote: Sun Jun 13, 2021 13:22 You get a bit, but not a lot, of extra capacity from the 2-lane exit. I know that theoretically left-turners could be taking the nearside lane exit while oncoming right-turners could be taking the offside lane exit, to merge subsequently, but that doesn't happen in practice, as those right turners start to move towards the nearside while still negotiating the roundabout, and that in turn leads to (quite rightly) hesitance by left turners joining the roundabout.
A few years ago I posted on Sabre about poor driver behaviour at UK multi-lane roundabouts - which is strange considering their national ubiquity. I recall a fairly lengthy dialog about two practises that steal capacity: 'straight-lining' and short-cutting back to the left at 2-lane exits (as described in the quote above). I suppose the latter practise is hardly surprising since the Highway Code endorses it:

UK highway-code roundabout.jpg

In contrast, the on-line highway-code-equivalent in Australia (Victoria) explicitly instructs a lane-disciplined exit from such a roundabout. See the short video here -

https://www.vicroads.vic.gov.au/safety- ... oundabouts

And guess what - it actually happens. Compliance isn't universal, so caution is required, but many AU drivers are prepared to take the fully-outside path, not straight-line; and also to leave the left-lane of an exit vacant for side-by-side entry. This applies even where the 2-lane exit immediately merges to one lane.

I'm normally able to rely on this happening when I'm taking the first left exit. I do look for eye contact, or cues that show the other driver's intention. However, when I drive in the UK (frequently), I know that I can't risk it, and so I wait, delaying myself and others, and wasting the roundabout's capacity.

Why the difference? Perhaps we're more used to being in right lanes. We tend to select lanes more by destination than by speed: there is no law prohibiting under-taking, and in fact it's normal. Some of our lane practises might fall into the Sabre thread about 'middle-lane hoggers'. And perhaps we're more patient, which might also explain why we're happy to wait at a traffic signal, causing delay when quiet but improving flow overall when roads are busy. And to wait at on-ramp signals. And to comply with covid lockdowns ...?
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Re: Unsafe roundabout design - North East

Post by FosseWay »

Peter Freeman wrote: Mon Jun 14, 2021 12:51
WHBM wrote: Sun Jun 13, 2021 13:22 You get a bit, but not a lot, of extra capacity from the 2-lane exit. I know that theoretically left-turners could be taking the nearside lane exit while oncoming right-turners could be taking the offside lane exit, to merge subsequently, but that doesn't happen in practice, as those right turners start to move towards the nearside while still negotiating the roundabout, and that in turn leads to (quite rightly) hesitance by left turners joining the roundabout.
A few years ago I posted on Sabre about poor driver behaviour at UK multi-lane roundabouts - which is strange considering their national ubiquity. I recall a fairly lengthy dialog about two practises that steal capacity: 'straight-lining' and short-cutting back to the left at 2-lane exits (as described in the quote above). I suppose the latter practise is hardly surprising since the Highway Code endorses it:


UK highway-code roundabout.jpg


In contrast, the on-line highway-code-equivalent in Australia (Victoria) explicitly instructs a lane-disciplined exit from such a roundabout. See the short video here -

https://www.vicroads.vic.gov.au/safety- ... oundabouts
I would not characterise the UK advice for turning right, as you show above, as "not lane-disciplined". There are a number of issues with mandating that drivers must leave the roundabout in the right-hand of two available lanes after turning right. Some of them admittedly may be more likely to be an issue in the UK than Australia given the tendency towards broader roads with more room in all directions in Aus.

1. In the case of the green car in the HC example above, it shouldn't matter which exit lane it takes because there shouldn't be anything alongside once it's passed the straight-on exit. People shouldn't be turning right from the left lane, and people shouldn't be setting off from the left arm at the same time as someone already on the roundabout is still passing the entrance. The only slight issue is cyclists, who may be "recommended" to use the left lane all the way round. Personally there's no way in the world that I'd try to turn right from the left lane; it's asking to be T-boned, but nevertheless, the advice does occur sometimes, and any driver turning right does need to be aware of cyclists potentially doing this.

2. On the subject of cyclists, I'm quite happy to use a roundabout in the intended way, so right lane to turn right, but I don't want to be in the outer lane of the road I exit into (unless I'm shortly turning right again). That's the worst place for a cyclist to find themselves, just as surrounding traffic is accelerating and concentrating on completing its manoeuvre. You want to get back over to the left once you've passed the straight on exit.

3. Urban areas in Britain are often not particularly planned, with several turns in quick succession. It's entirely possible for there to be a left turn a few tens of metres after the right-hand exit from that roundabout, and if you want to take that exit, you need to be in the left lane. The requirement to position yourself in good time for your intended manoeuvre doesn't suddenly not apply just because the stretch of road immediately before your turn happens to include a roundabout. As I say, this kind of crowded layout may be less of an issue in Australia.

4. I'm not aware that there is a concerted tendency to tell people on the approach to a roundabout how many lanes the exit has, especially exits other than the main line (usually straight on). In other words, a driver approaching the roundabout to turn right won't know how many lanes there are on the exit road till they see it, after passing the straight ahead exit. A related point is that there are plenty of roundabouts with two lanes, where less major exits off them only have one. This rule then essentially requires them to exit the roundabout from the outside lane, which I would have thought is contrary to both the HC and common sense.
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Re: Unsafe roundabout design - North East

Post by JohnnyMo »

mbeatts wrote: Sun Jun 13, 2021 16:18 Here's a shot of what it used to be like, think one issue is a lot of people are used to sitting in the right hand lane coming from the east to go straight over but when the new bit opened, caused people to undertake in the new second left hand lane.

No foot traffic up here but does get very busy coming from south to east.

roundabout2 (1).jpg
From the tyre marks, and markings it would seem much of the traffic was going straight across. The chicane effect of the roundabout was minimal and so did not slow the traffic enough.

Design of new layout will force, traffic to take a slower line as it is more tightly funnelled, the the traffic island preventing traffic taking anything but the required route across the roundabout.
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Re: Unsafe roundabout design - North East

Post by marconaf »

The other issue with taking the right hand lane of an exit is usually it then merges into the left (although this example bizarrely tells the right lane to merge, but the lane that carries on is the right!), thus it makes no sense not to go straight to the left if it’s available as otherwise you end up having to then do another movement.

On large, ie 3 lane roundabouts it is usually possible to pull out for a left turn and be clear of traffic coming around the roundabout for the same exit, but on a smaller one not so. Hard to see the latter adds any real inefficiency and I’m all into marginal gains where they exist.

The root problem really is we use roundabouts for everything, so not only do people get fed up / complacent / lazy (hence straightlining, which I do if nothing is around, as why not) but we’re trying to get too much through it. The A3/M25 Jn is a classic, what should be freeflow as per M25 & M3/4/40 Jns has a roundabout which can’t cope, and at cost of we’re just making it a bigger roundabout.

Merging the UK is appalling at, but not helped by road layouts which split then recombine (as post’s layout does) because that usually doesnt make pulling over worthwhile (given the faff of doing 2 maneouvres vs staying in one place), but allows the “keen” to over/undertake a bunch of vehicles which not unreasonably is seen as “a bit off”. The other extreme as I saw on the A303 last week is someone bringing the mainline to an emergency halt as they slowed almost to a stop to allow someone to come off the slip, then when that person (who had clearly been slowing to go behind the mainline car) eventually crawled just in front of them, they then suddenly pulled out to the outside lane because they were both so close. Had they of course continued at their previous speed unabated it would all have been smooth. But such is the result of over zealous desires to “help”.
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