CTC capitulation?

[benb]

Er no. That's your interpretation. Apart from anything else you are forgetting that the Dutch are adding these to existing roads where the cycle networks already exist and already involve extensive segregation. You are also forgetting that the Dutch approach to roundabout design is quite different from the UK, so you can't assume that applying a turbo design to replace a UK roundabout will be worse for cyclists. Any chance of anyone bothering to read the reports posted earlier?

Er, no. The Dutch approach is not to have cycle traffic going through turbo roundabouts.

 

[jonesy]

Er, no. The Dutch approach is not to have cycle traffic going through turbo roundabouts.

I take it the 'no' is your answer to my last question...

 

[benb]

I take it the 'no' is your answer to my last question...

Perhaps you can clarify what you mean, as I am having trouble following you.
Do the Dutch turbo roundabouts route cycling traffic through them, as will be the case here? yes or no? (hint: the answer is no)

 

[User169]

This depends on how big the divisions are. Again Netherlands drivers aren't a special breed, they will be impatient at times and look for a short cut - how does Holland maintain segregation, how easy is to go over the divisions there?

I think it's something you'd only do once (per car).

 

[jonesy]

Thank you @TMN.

I would have hoped by now that the complainers would have appreciated that there is rather more to roundabout design than a simplistic "if it isn't exactly the same as the Dutch then it must be wrong" argument, taking no account of context, starting point etc...

 

[jonesy]

M

Perhaps you can clarify what you mean, as I am having trouble following you.
Do the Dutch turbo roundabouts route cycling traffic through them, as will be the case here? yes or no? (hint: the answer is no)

My question was about whether anyone was going to take the trouble to read the reports posted previously. Clearly your answer is no...

 

[jonesy]

Continental geometry is of itself not new ( but then I never said it was), however it is still not standard practice in the UK. High capacity roundabouts do not use it. The turbo roundabout, which uses aspects of continental geometry as well as physicallly separated spiral lanes, is new however. I'm unclear what regulator's point is though.

 

[Wobblers]

Well, you managed to "publish" those 4 paragraphs with no supporting evidence at all! - but I suppose you also refrained from actually making any point whatsoever - just giving the impression of doubt.

It is not an "assumption" that drivers need to slow down for tight bends - it is a physical limitation. Perhaps as a physicist you could take the trouble yourself to do the maths to calculate the maximum possible speed that a vehicle can follow a 15m radius bend with only the friction of the tyres to provide the necessary centripetal force - allow say a coefficient of friction of 0.65 for a rolling tyre on tarmac. I did supply a helpful link if you cant remember the basics:
http://www.stevemunden.com/leanangle.html

Are you seriously doubting that lower speeds make for a safer environment? or just making a silly debating point?
Perhaps this might help:
https://www.swov.nl/rapport/Factsheets/UK/FS_Speed.pdf

Now for sightlines. The perpendicular arms mean that drivers nearing the junction will have a better view of circulating traffic than with the standard UK tangential arms. So drivers are more likely to cyclists, thus making the junction safer.

Lane dividers are provided to ensure vehicles keep to the lanes and trucks will need to occupy the whole lane. The lanes won't be wide enough for cyclists to overtake on the wrong side or for left turning trucks to attempt to overtake cyclists - and there won't be cycle lanes to encourage conflicting movements through the junction or traffic lights to generate stationary traffic, so this should greatly reduce the left hook problem.

Dearie me. Had a bad morning? Why not put your feet up and have a cup of tea.

If you want to be taken seriously, it's probably best not to go off on some tiresome tirade. Especially in reply to someone who's already said that an increase in safety is "not unreasonable". If that double negative was too troublesome the I'll restate it: "I think that it is reasonable that this type of roundabout may increase the safety of vulnerable road users".

I do hope this helps.

Now, if you could kindly refrain from petulance, can you answer my questions on this 70% reduction in crashes. This, after all, is the evidence you need to support your conclusions. Do these figures include all vehicles, as well as cyclists? And what is the standard deviation?

PS: A friction coefficient of 0.65 is what I'd expect to see for a tyre on a poor surface in the wet. I think it unlikely that part of the improvements would be to replace the road surface with broken concrete and convert it into a skid pan. After all, the water bill would be horrendous! Assuming that motorists are au fait with the finer points of physics seems a trifle... optimistic. Physics is only a part of the whole package of factors - psychological factors are at least as important: which is why a blanket assumption that slower speeds automatically means increased safety in all circumstances is unwise.

 

[StuartG]

In support of McW's comments I would add that a driver is acting on his/her perception of the road or junction and not necessarily with the reality. The two can differ significantly. This can be advantageous when a junction appears more dangerous than it is. Disaster when it is the other way round.

Hence we have a problem when people want the apparent danger removed. It would seem the sensible thing to do to a lay person. Which is why it is not a good idea to let lay people design junctions. It is a good idea that the professionals be held to account on the results and ensure these results are produced in an accessible way to lay people. Of course if lay people don't bother with the evidence they should, for safety's sake, be ignored.

My career was based on statistics and modelling. I would have been out of a job if we could rely on common sense or not taking into account hidden interdependencies. It was discovering the unexpected, where common sense is wrong, that saves lots of money, lives or both depending on the application. This is particularly true in traffic management. The biggest hurdle is when the safety situation is counter-intuitive. No matter how strong the evidence a certain section will always resist because they just 'know'.

 

[jonesy]

As a general statement that is fine, Nonetheless, it simply isn't controversial that reducing turning radii reduces traffic speed...

 

[jonesy]

Because such designs don't normally have cyclists funneled around them nor are they trumpeted as being 'cyclist friendly'...

Such designs aren't normal in the UK, full stop. It is a trial, you can't make general statements about what is or is not normal. There are some design features that would be expected to make it better than the existing layout, there are others that raise concerns. But until it is tried we don't know. Simplistic comparisons with Dutch practice, where a lot of other factors are different, don't enable us to prejudge the outcome of this trial.

 

[jonesy]

Except they are more 'normal' than people wish to acknowledge. First we're told we don't have 'turbo roundabouts' in the UK... and then it's pointed out that we do and examples provided. Then it's suggested (via a rather outdated TAL) that the angles of approach etc are different.... except such angles of approach etc. are becoming more common on smaller roundabouts.

Other than the amount of white paint used, the reality is that there's actually not a great deal of difference between the Bedford design and many similar designs already in use in the UK.



Yet the fact that it is a trial doesn't stop you banging on about how it *will* reduce average speeds...



I'm sure I don't have to point out the rather obvious prejudged conclusions that some people who are enthusiastic about the design have been jumping to...

At the risk of boring repetition, the fundamental design feature is the physical separation of the lanes and that is new to the UK. The use of tight geometry is necessary to reduce speed, but, and I will keep banging on about it until it sinks in, this is not controversial. Indeed, it isn't new.- hence the .1997 TAL - and is clearly recommended in DFT and Tfl's guidance on cycling infrastructure. It just isn't usually used on high flow roundabouts because it reduces capacity. So, once again, I'll point out that if traffic capacity was the main objective they would simply have built a high capacity roundabout to UK geometry, and it would be a nightmare for cyclists.

 

[jonesy]

Quite. So we are all in agreement that there are potential benefits, but also potential problems, so let's see what the trial brings?

 

[Flying Dodo]

Yes they are. That's the whole point of providing the farcilities on the new Bedford roundabout. It's about getting cyclists out of the way of drivers and putting them onto the paths and crossings around the roundabout..

You definitely haven't bothered reading the link I'd referred to some time ago to what Patrick Lingwood, the Bedford Cycling Officer posted, bearing in mind the ratio of "road" cyclists to non road cyclists was 60:40 and he expected the road cyclists to carry on using the road, and taking the lane.

Quite. So we are all in agreement that there are potential benefits, but also potential problems, so let's see what the trial brings?

Yes.

Although bearing in mind I'm probably the only one posting about it who's actually been around this roundabout, I'm not sure how to tempt all these arm chair critics to actually get on a bike and try the new version.

 

[GrumpyGregry]

Although bearing in mind I'm probably the only one posting about it who's actually been around this roundabout, I'm not sure how to tempt all these arm chair critics to actually get on a bike and try the new version.

Travel to Bedford to try a roundabout.

Hmmmm..... can I volunteer for root canal work instead?