Fendon Road Roundabout, Cambridge.

[Pete Owens]

please back them up with evidence.

SWOV 2004
https://www.swov.nl/sites/default/files/publicaties/rapport/r-2004-14.pdf
English summary on page 5:
The third phase involved studies of the safety differences between cyclists having priority or not on separate cycle tracks on the outside of urban roundabouts. These studies showed that more injury crashes occurred if cyclists on these cycle tracks had priority than if they did not.

CROW 2017
https://www.fietsberaad.nl/Kennisbank/Hernieuwde-aandacht-voor-de-veiligheid-van-fietser
It is striking that on roundabouts in built-up areas with a separate cycle path with cyclists IN priority, an average of 0.73 cycling accidents per roundabout were registered in the period 2015 - 2018. On roundabouts with OFF priority for cyclists, an average of 0.18 accidents per roundabout were registered in four years.

[Pete Owens]

And to see the sort of problem you will see at the Cambridge roundabout look at this BBC report of the trial layout being tested:
https://www.bbc.co.uk/news/av/uk-england-london-22350776/dutch-style-cycle-roundabouts-for-london-tested
Two minutes in. Just as well the cyclist was alert.

And that from just be a short recording session - in as controlled situation where the drivers knew they were involved in a trial about cycling so were looking out for them. Where the setting was very controlled - no distractions - in daylight - no one in a hurry to get to work. Where the cyclists were employees rather than the public - all wearing high-vis and taking a great deal more care than you would expect to in a situation where you had marked priority.

[Manc33]

Drivers: "Stop cycling on my part of the road".
Cyclists: "Stop driving on my part of the path".

[thirdcrank]

It would be easy to believe that some cabal of highwaymen had decided to discredit the whole concept of cycling provision. It's a lot to spend but it's not coming out of their back pockets so that will just add to the scorn heaped on it.

AIUI, the purpose of roundabouts is to maximise capacity, not to act as traffic-calming. I'm only guessing but this design seems to risk congestion. In the absence of enforcement, compliance with GIVE WAY requirements is often poor. Cyclists and pedestrians tend to prefer the shortest line so I could imagine some of the former would often use the main carriageway and the latter would use the cycle track when going straight ahead. I would also expect that riders turning right would go anticlockwise (90 degs rather than 270 degs) adding to the apparent confusion.

[backnotes]

It was covered on the local ITV news yesterday evening. First image opens a 2:32 video segment.

https://www.itv.com/news/anglia/2020-08-07/uks-first-dutch-style-roundabout-continues-to-spark-debate-in-cambridge-a-week-after-opening

[Pete Owens]

EEk... In what was presumably a couple of hours of filming they have observed an awful lot of motorists failing to give way to the cycle path.

[Manc33]

Is there a subway under it for bikes?

[Bmblbzzz]

"In the Netherlands the guidelines are clear: in the built-up area cycling must have priority over motor traffic and outside the built-up area it is the other way around"

This doesn't fit with your statement:

"The Dutch compared the relative safety of giving priority to cyclists or motors - and found the later to be significantly less dangerous - so now mark the give way markings to give priority to the main carriageway"

Read all of the article, not just the bits that fit with your agenda. And when you make wild claims, please back them up with evidence.

Interesting. Probably wouldn't work in UK because, unlike NL (and most of Europe), we don't have a clear and distinct division of roads into urban and non-urban. The town skyline sign does this nicely in most European countries, here there would be all sorts of grey areas; suburbs, villages, odd bits of development.

[Bmblbzzz]

Another difference is angle of entry and departure, as well as radius.

[Cyril Haearn]

A bit like shared space, causing confusion in the hope people are careful?
I am not convinced

[Bmblbzzz]

No, I would say it's the opposite. Everything is clearly marked out. There may be confusion because it's new, and some (most?) people aren't very good at coping with new things on the fly, but that's just as it was with mini-roundabouts when they were first introduced; would you really still say those are confusing?

[Pete Owens]

Another difference is angle of entry and departure, as well as radius.

It is these things that are the key differences between cycle friendly continental compact roundabout geometry and high speed UK jobs - not the peripheral segregated stuff that is very common in the UK. The basic geometry of this particular roundabout is very good in this respect, with the perpendicular single lane entry and exit arms and single circulating lane - the central island could do with being a bit bigger to increase the deflection on entry.

While there have been guidelines for for cycle friendly roundabouts in the UK for a quarter of a century https://webarchive.nationalarchives.gov.uk/+/http://www.dft.gov.uk/adobepdf/165240/244921/244924/TAL_9-97/ , they are very rare here because they have a slightly lower capacity - anathema to UK traffic engineers. This example is not the first in the UK or even in Cambridge - for example the Perne Road roundabout back in 2014. https://www.cyclestreets.net/location/61691/

[Pete Owens]

AIUI, the purpose of roundabouts is to maximise capacity, not to act as traffic-calming.

The purpose of roundabouts is very much to improve safety by acting as traffic calming. Cross roads are the most dangerous form of junction with nothing to naturally slow traffic from either direction you are relying on drivers on the designated minor approach to notice road signs while drivers on the designated major approach speed through without slowing at all. Both streams of traffic see a straight road heading into the distance so mistakes are made - and those result in high speed collisions.

Unfortunately speed and capacity are the overwhelming concerns of UK highway engineers so they design roundabouts to be taken at speed as opposed to continental designs aimed at slowing the traffic - which is why they are nasty for cyclists in the UK. The nastiness is not an inherent feature of roundabouts, but a peculiarity of the way they are designed in the UK.

To understand the difference the geometry makes think of a compact roundabout as a stretch of single lane one-way street with 4 T-junctions on the left hand side. Nothing tricky for the cyclist - just 2 conventional left hand turns - the easiest junction manoeuvres for us.

UK roundabout geometry is arranged like a high speed multi-lane dual carriageway with arrow-point merging and filtering to join and leave - which are particularly tricky manoeuvres for us.

[Bmblbzzz]

I'd definitely second those comments on the size and angles of roundabouts, from direct experience abroad. Unfortunately though, UK is not the only country to design roundabouts for speed and volume - I've known some abroad that are almost a circular island within a square of road, so straight are the approaches and departures. When this combines with rules which sometimes give priority to traffic entering the roundabout, it's really not fun.

[Navara]

Not a good start!
https://uk.yahoo.com/news/britains-firs ... 25386.html
Closed after a driver hits a beacon and drives off