Bedford turbo roundabout - it is done

User avatar
mjr
Posts: 16600
Joined: 20 Jun 2011, 7:06pm
Location: Norfolk or Somerset, mostly
Contact:

Re: Bedford turbo roundabout - it is done

Postby mjr » 18 Nov 2016, 10:08pm

The utility cyclist wrote:On the Bedford roundabout there are two crossings for each road traversed, it is not a singular zebra crossing both lanes on each road thus 4 crossings in total. It's around 3-4 times the distance and […]

Surely you don't need to cross the lanes you start and finish in? Well, unless you really want to.
MJR, mostly pedalling 3-speed roadsters. KL+West Norfolk BUG incl social easy rides http://www.klwnbug.co.uk
All the above is CC-By-SA and no other implied copyright license to Cycle magazine.

Pete Owens
Posts: 1928
Joined: 7 Jul 2008, 12:52am

Re: Bedford turbo roundabout - the future

Postby Pete Owens » 19 Nov 2016, 12:00am

The utility cyclist wrote:Cambridge is to receive it's very own 'turbo' roundabout shortly, http://road.cc/content/news/211156-camb ... roundabout

That is a compact roundabout rather than a turbo roundabout, but the principle is the same - use tight geometry in order to reduce traffic speeds. It will the second example in Cambridge following this one:
https://www.ucl.ac.uk/transport-institute/pdfs/alasdair_massie
That has seen a dramatic improvement to safety at what used to be an accident black spot.

The lower speeds benefit ALL users and makes it safer for everyone.
For cyclists riding on the carriageway (which is what these designs are principaly aimed at) it is much more friendly.
For pedestrians or cyclists using the zebra crossings become much easier to cross.
It even makes it easier for drivers trying to join the roundabout to judge a safer gap in the traffic.

The proposal for the turbo in Cambridge I would presume is on the back of this by TRL http://www.bbc.co.uk/news/uk-england-london-22350776 which I thought I remembered one of the forum posters here going on or was at least one of those that were used by TRL
That it still had a near miss in perfect conditions, riders wearing hi-vis, no distractions, all drivers instructed beforehand, low levels of traffic, during the day highlights the flaws in the design.

Yes, that is the video - at about 2 minutes in.
What It shows the inherent flaws of orbital cycle paths crossing the entry and exit arms of roundabouts, rather than a problem with compact geometry - while that was a near miss in those conditions, a similar orbital path crossing the entry/exit arms of a conventional high-speed UK geometry roundabout would be lethal. Even the Dutch now make cycle paths yield priority in these sorts of situations due to safety concerns.

User avatar
gaz
Posts: 14133
Joined: 9 Mar 2007, 12:09pm
Location: Kent, lorry park of England

Re: Bedford turbo roundabout - it is done

Postby gaz » 19 Nov 2016, 10:45am

If you want to see a real dog's dinner of a roundabout please take a streetview tour around this one. I have no idea what design manual they were reading, it clearly wasn't written in Dutch.

The cycle facilities have been remodelled in the last 12 months, you can see previous version on the timeline.
There'll be tarmac over, the white cliffs of Dover ...

reohn2
Posts: 40702
Joined: 26 Jun 2009, 8:21pm

Re: Bedford turbo roundabout - it is done

Postby reohn2 » 19 Nov 2016, 11:41am

gaz wrote:If you want to see a real dog's dinner of a roundabout please take a streetview tour around this one. I have no idea what design manual they were reading, it clearly wasn't written in Dutch.

The cycle facilities have been remodelled in the last 12 months, you can see previous version on the timeline.


I'll bet the design 'engineers' treated that design as a game of blindmans bluff :twisted: :twisted: :twisted:
-----------------------------------------------------------

User avatar
The utility cyclist
Posts: 3577
Joined: 22 Aug 2016, 12:28pm
Location: The first garden city

Re: Bedford turbo roundabout - the future

Postby The utility cyclist » 19 Nov 2016, 4:41pm

Pete Owens wrote:
The utility cyclist wrote:Cambridge is to receive it's very own 'turbo' roundabout shortly, http://road.cc/content/news/211156-camb ... roundabout

That is a compact roundabout rather than a turbo roundabout, but the principle is the same - use tight geometry in order to reduce traffic speeds. It will the second example in Cambridge following this one:
https://www.ucl.ac.uk/transport-institute/pdfs/alasdair_massie
That has seen a dramatic improvement to safety at what used to be an accident black spot.

The lower speeds benefit ALL users and makes it safer for everyone.
For cyclists riding on the carriageway (which is what these designs are principaly aimed at) it is much more friendly.
For pedestrians or cyclists using the zebra crossings become much easier to cross.
It even makes it easier for drivers trying to join the roundabout to judge a safer gap in the traffic.

The proposal for the turbo in Cambridge I would presume is on the back of this by TRL http://www.bbc.co.uk/news/uk-england-london-22350776 which I thought I remembered one of the forum posters here going on or was at least one of those that were used by TRL
That it still had a near miss in perfect conditions, riders wearing hi-vis, no distractions, all drivers instructed beforehand, low levels of traffic, during the day highlights the flaws in the design.

Yes, that is the video - at about 2 minutes in.
What It shows the inherent flaws of orbital cycle paths crossing the entry and exit arms of roundabouts, rather than a problem with compact geometry - while that was a near miss in those conditions, a similar orbital path crossing the entry/exit arms of a conventional high-speed UK geometry roundabout would be lethal. Even the Dutch now make cycle paths yield priority in these sorts of situations due to safety concerns.

I never called it a 'turbo' but it is being labelled as such by the designers and those funding it so whatever. If it isn't a true turbo then why is allowed to be expressed as such and no doubt cycle money being spent on it when it doesn't improve matters.
You were big on the Bedford rubbish and happy that cycling money was spent on that, are you going to keepp championing this garbage...again?

You mention lower speeds, by whom, motorists? people on bikes will have to go slower, motorists will continue as before, these are UK drivers, they are nothing like those in the Netherlands when it comes to ceding way to people on bikes, it could be decades if ever before we have a shift in attitude to make these 'facilities' safe.
Personally I'm against 'turbo' or whatever nonsense it's called, it serves no purpose with respect to making cycling safer and in the same instance it increases the journey time and inconvenience of those choosing to travel by bike.

Pete Owens
Posts: 1928
Joined: 7 Jul 2008, 12:52am

Re: Bedford turbo roundabout - the future

Postby Pete Owens » 19 Nov 2016, 9:42pm

The utility cyclist wrote:
Pete Owens wrote:
The utility cyclist wrote:Cambridge is to receive it's very own 'turbo' roundabout shortly...

That is a compact roundabout rather than a turbo roundabout...

I never called it a 'turbo'...

:roll:

SA_SA_SA
Posts: 2000
Joined: 31 Oct 2009, 1:46pm

Re: Bedford turbo roundabout - it is done

Postby SA_SA_SA » 21 Nov 2016, 2:28pm

Given that the purpose of the on-road part of the UK design derived from a Dutch Turbo roundabout is to slow speeds, they should probably call it something other than Turbo-style, if only too avoid confusion with the Dutch Turbo which has the opposite intention, hence name:

the High-Capacity-Tortoise roundabout perhaps?
------------You may not use this post in Cycle or other magazine ------ 8)

Pete Owens
Posts: 1928
Joined: 7 Jul 2008, 12:52am

Re: Bedford turbo roundabout - the future

Postby Pete Owens » 21 Nov 2016, 9:33pm

The intention of original dutch turbo roundabouts was very much to slow traffic - see this paper from the originator of the concept:
http://www.cedr.fr/home/fileadmin/user_upload/en/Thematic_Domains/Strat_plan_1_2005-2009/3_TD_Operation/1_TG_Road_Safety/8_The_Hague_5_6-03-09/Minutes/8_Turbo_Roundabouts_Paper.pdf
"Turbo" never referred to speed, but to the turbine like shape of the roundabouts.

Fortuijn wrote:The challenge was to develop a roundabout with a same or a higher capacity than the two-lane
roundabout, but with the same safety features as the single-lane roundabout. The new roundabout
would have to meet the following conditions:
- no lane changing on the roundabout;
- no need to yield to more than two lanes;
- low driving speed through the roundabout.

Pete Owens
Posts: 1928
Joined: 7 Jul 2008, 12:52am

Re: Bedford turbo roundabout - the future

Postby Pete Owens » 22 Nov 2016, 12:09am

The utility cyclist wrote:You were big on the Bedford rubbish and happy that cycling money was spent on that,

I was indeed very keen on the the original proposal for a turbo roundabout at Bedford - it would probably have been the single best use of the cycle safety funding had it gone ahead. I was also extremely sceptical of the modified design, which stripped out the turbo design element at the behest of the motorcyclists. I suspect the designers also had less faith in the modified design since they moved the zebra crossings further from the pedestrian desire lines. However, after looking at the evaluation posted by thirdcrank, even the compromise design still looks to have been a worthwhile investment. I hadn't realised the importance of the extended kerbs (the bits with the posts on).
You mention lower speeds, by whom, motorists?

Yes - look at the evaluation:
https://www.ucl.ac.uk/transport-institute/pdfs/patrick_lingwood
The before and after circulating speeds are plotted on page 40 - free-flow traffic speeds are down to 14 mph. This may have slowed faster cyclists a tad, but the main impact is on motorists.

User avatar
mjr
Posts: 16600
Joined: 20 Jun 2011, 7:06pm
Location: Norfolk or Somerset, mostly
Contact:

Re: Bedford turbo roundabout - it is done

Postby mjr » 22 Nov 2016, 3:11am

Designer in Favour of Own Scheme Shock! News At Ten! :roll:

Is there an independent evaluation yet other than the critical one posted earlier?
MJR, mostly pedalling 3-speed roadsters. KL+West Norfolk BUG incl social easy rides http://www.klwnbug.co.uk
All the above is CC-By-SA and no other implied copyright license to Cycle magazine.

User avatar
The utility cyclist
Posts: 3577
Joined: 22 Aug 2016, 12:28pm
Location: The first garden city

Re: Bedford turbo roundabout - it is done

Postby The utility cyclist » 22 Nov 2016, 12:00pm

Excuse me whilst I laugh my socks off, I'd read that 'evaluation', what a load of balony. As for highlighting lower motor vehicle speeds, well they might say that but the final design certainly hasn't slowed vehicles down coming toward or off the roundabout, you can still easily in a modern car turn left at 30mph or more should you wish and a heavily laden goods vehicle could manage 20+ no worries at all. Now, you're cycling across the zebra to the centre bit where it's not even wide enough for a bike length and mr in a hurry skip lorry comes ploughing around the bend and you think you're safe to keep going or they clip the back of your bike that's protruding out. I'm sure they thought it all through though, I'm sure they realised making the journey far longer, more complicated and more hazardous for people on bikes would have exactly the effect they wanted! :twisted: Welcome to New South Wales style governing, next being fined for not using the infra, fines for no bell, fines for no plastic hats/hi-vis.

I can hardly see the one proposed for Cambridge lowering the speed of motorists but oh yes, we will be told it will do so..yackity yack.

SA_SA_SA
Posts: 2000
Joined: 31 Oct 2009, 1:46pm

Re: Bedford turbo roundabout - the future

Postby SA_SA_SA » 22 Nov 2016, 7:31pm

Pete Owens wrote:The intention of original dutch turbo roundabouts was very much to slow traffic - .....
"Turbo" never referred to speed, but to the turbine like shape of the roundabouts.
.....

Abbreviating Turbine to turbo seems to result in an unfortunate misunderstanding (although I suppose one doesn't think of turbines as related to slowness due to jet engines...) :

does turbo mean something else/less contradictory in Dutch?

A less misleading name would still seem a good idea.
------------You may not use this post in Cycle or other magazine ------ 8)

Pete Owens
Posts: 1928
Joined: 7 Jul 2008, 12:52am

Re: Bedford turbo roundabout - the future

Postby Pete Owens » 22 Nov 2016, 9:28pm

SA_SA_SA wrote:
Pete Owens wrote:The intention of original dutch turbo roundabouts was very much to slow traffic - .....
"Turbo" never referred to speed, but to the turbine like shape of the roundabouts.
.....

Abbreviating Turbine to turbo seems to result in an unfortunate misunderstanding (although I suppose one doesn't think of turbines as related to slowness due to jet engines...) :

does turbo mean something else/less contradictory in Dutch?

A less misleading name would still seem a good idea.


I guess it wouldn't occur to the Dutch that traffic engineers might be doing anything other than making junctions safer by controlling speed.

Bmblbzzz
Posts: 3758
Joined: 18 May 2012, 7:56pm
Location: From here to there.

Re: Bedford turbo roundabout - it is done

Postby Bmblbzzz » 23 Nov 2016, 11:49am

I've used a few compact roundabouts on a bike, on foot, by car and by bus. None of them in the UK or NL (the idea is spreading internationally). I'm very much in favour of them in most situations as preferable to typical UK-style roundabouts. I think the three key elements in reducing vehicle speeds on them are the single-lane approach, the sharp angle of turn on entering and leaving the circulating carriageway, and the single, relatively narrow, circulating lane which prevents overtaking without stopping long vehicles from turning (they can overhand the rubble area surrounding the central island). The ones I've used have been on suburban and rural main roads and though some have pedestrian crossings (zebra) on the arms, none have had cycle lanes. IMO they haven't actually needed them as these features mean the traffic circulates at cyclist speed and the natural place to cycle is in the middle of the carriageway, so this is what everybody does there. In addition, cycling on the pavement and across the zebras is totally tolerated there, though I'm not sure it's actually legal. I guess UK drivers might be less tolerant of this but it would vary by place and time of day.

The one disadvantage of compact roundabouts IME is capacity; they're always preceded by long queues on the approach roads. It's also noticeable that they lead to a different approach to priority; because traffic moves so slowly and probably also due to the long waits to reach the junction, people don't wait for a large gap to enter the roundabout and those already circulating accept they will slow down to allow this to happen; it's more give and take than priority based. Cyclists, needing less of a gap, actually benefit from this.