Friday 25 June 2021

Fabulous Fendon Road

You wait ages for a post about roundabouts and three come along at once. After looking at the proposals for North Tyneside and the continental roundabout in Islington in recent weeks, have I actually found a Dutch-style roundabout in the UK?

Well, the other week, I took my trusty folding bike to Cambridge to have a look at a scheme I had hoped to visit last year, but lockdown meant I couldn't travel more than locally. 

The scheme is the Fendon Road roundabout which was rebuilt as a UK equivalent of a type of Dutch urban roundabout where walking and cycling is prioritised over traffic. As a reminder, the Dutch guidance looks like this for this type of roundabout (with general and cycle traffic orbiting anti-clockwise);

This is the CROW Design Manual layout. There are quite a few dimensions to think about;
  • R1 (radius to edge of circulatory area) = 12.5m to 20m
  • R2 (radius to outside of central kerbed island) = 6.5m to 15m
  • ra (entry radius) = 12m (with the central kerbed island)
  • rb (exit radius) = 15m (with the central kerbed island)
  • B (circulatory lane width) = 5m to 6m (depending on R1 and R2)
  • b1 (overrun apron) = 1.5m (minimum of 1m)
  • b2 (cycle track width) = 2m to 2.5m
  • b3 (cycle cross approach) = as large as possible
  • L (distance from edge of roundabout to cycle track crossing) = 5m
The various dimensions affecting the carriageway are designed to require the drivers of small to medium-sized motor vehicles to actually slow down and use their steering wheels which means that interactions with people walking and cycling across the arms and other drivers within the junction are controlled. 

If there is collision, then speeds are low and the risk of serious injury is reduced - sustainable safety in action (but it doesn't eliminate safety risks). The overrun apron gives the drivers of larger vehicles a little more space without making it easier for the drivers of smaller vehicles to speed. The absolute key to the design is having one traffic lane in and out on each arm.

The 5m set back of the cycle crossing means there is space for drivers to stop as they leave the roundabout and the crossing is in a location where driver speeds from both sides are low. The landing for the floating zebra crossing gives people walking some space to pause between crossing the cycle track and then the traffic lanes. 

Dimension b3 is worth pointing out because the larger this is, the more time people driving and cycling have to see each other people cyclists cross - it's gives a little more chance for people to react. My thanks to Calum for noticing a nuance which I had missed. Of course, this dimension also makes sure pedestrians get a decent bit of space between the cycle track and carriageway.

You'll notice there isn't a width of the refuges within the crossings specified because these are more about keeping drivers regimented than expecting people walking and cycling to wait - they are given priority after all; but the refuges are rectangular to force lower driver approach speeds. The usual UK approach is to have triangular refuges to make it easier to driver through at speed. It's worth noting that in the UK, that the addition of refuges to zebra and parallel zebra crossings means that they should be treated as two crossings by users.

I'm not going to go into each detail of the Fendon Road scheme, but on the whole, most of the key issues are dealt with in what is actually a pretty challenging site space wise.

The photograph above is the view into the roundabout from the western arm of Queen Edith's Way. On the approach, there is no cycling infrastructure on what is a pretty horrible road to cycle along. To join the layout, one merely moves to the left to join the cycle track. There are no dropped kerbs that would tip a trike user which is great. The four arms of the roundabout are not equally placed around a circle, the junction is skewed so pairs of arms have a small angle between them which makes it really hard to accommodate left turning vehicles.

The general arrangement of the roundabout has a low upstand kerb to the right (as you cycle orbitally clockwise) and a 45° splay kerb to the left (above). The mini-zebra crossings over the cycle track are on low humps with the levels such that there's a gentle slope across the crossing area from footway to carriageway. Some have suggested that drivers should also have to negotiate a humps which I have a little sympathy with, but the levels really work well and the roundabout geometry slows drivers anyway.

The designers have made the zebra crossings for pedestrians nice and wide which helps both with conspicuity and helps smooth the desire lines people take with different routes through the junction (above).

The vehicle entrance and exit points (the 'L' dimension) is 5 metres which meets the requirements for this type of roundabout and the orbital cycle track is properly circular and meets the carriageway nearly at 90°. This means that drivers wishing to turn left off the roundabout have a good view of cycle traffic and people cycling do not have to look behind them (but as a user, you do need to pay attention to what's happening). 

Because the cycle track is circular this does mean that the cycle crossings are not strictly parallel to the zebra crossings and so this doesn't comply with the daft rules on parallel zebra crossings which require a standard 400mm gap. I don't know if Cambridgeshire County Council is applying for a special authorisation for the layout from the Department for Transport (they should for completeness, and DfT should change this rule).

I've reproduced Figure 10.37 from LTN1/20 Cycle Infrastructure Design which does have "properly" parallel zebra crossings, but people just don't flow like that in a compact situation like this. I'd also point out that the figure's dimensions are lost because of the poor quality of the downloadable PDF.

One piece of detail I was a little concerned about was the choice of gully grating. On the one hand, the unit seeks to minimise intrusion into the cycle track and having part of it in the cycle track drains a bit better than an inlet unit which would be within the kerb. The issue is the longitudinal slots which are fairly short, but perhaps just long enough to catch a narrow or small wheel.

The circulatory area of the carriageway is compact to slow drivers down and features a kerbed apron with a stone sett infill. From a maintenance point of view, I do think that this will be a point of future failure because heavy vehicles and setts simply don't mix long term. I think I would have used imprinted asphalt in this situation as it could be formed to give a kerb-like edge and a textured surface to dissuade the drivers of small cars. 

The eastern arm of Queen Edith's Way is similarly poor for cycling beyond the roundabout, but again, there are decent transitions (above). One odd thing about this arm is that there isn't a parallel zebra crossing. There is an existing vehicle access to a house which means there is a cycle track that drivers give way to with a separate zebra crossing a little further out (below).

This is a perfectly legitimate layout, but it's not quite Dutch. But, it it's a practical solution to the problem and remains reasonably consistent with the design principles.

The junction has some really nice planting and as is the UK way, it has sprouted many Belisha beacons (featuring "halo" light up surrounds for maximum conspicuity - above).

The other little thing which made me smile were the bollards with little cycle and turn left traffic signs just to be sure, despite the layout being very legible and obvious to the user. 

The cycle tracks were perhaps a little tight in places, but they are machine-laid and red - something adopted all over Cambridge (and my favourite colour). If I were to be *really* picky, I would love to have seen the footways paved in light grey block paving to soften the the visuals of the scheme and to differentiate from the carriageway, but I can't have it all! 

Here's a short film of me cycling around the roundabout. What you don't see is me concentrating on what drivers are doing, but because the layout is so intuitive, I only need to worry about what's happening immediately near me. It's easy to see drivers leaving the roundabout as I approach the crossing and as I cross I can see what drivers to the left are doing, (reasonable) safe in the knowledge that the geometry is slowing drivers down - you can see the generally good driver behaviour in action and it all just flows.

The designers have worked incredibly hard to get this scheme squeezed in and working for all users - we often hear about "all users", but it's used correctly here. Before I sum up and offer some closing comments, it's worth having a look at this stunning video by Durman Stearn, one of the project's contractors.

You can really see the elegance of the project and how it all fits together from above.

So, is it Dutch? Pretty much and what is more, it shows that behavior can be changed through design. The UK is terrible at designing roundabouts, a subject I keep coming back to. We tend to design them for maximum traffic capacity whereas the Dutch tend to design them for safety and smooth traffic flow (maybe up to 25,000 vehicles a day for this type).

Slowing things down to speed up overall journeys is known across the North Sea as LARGAS which is an acronym (langzamer rijden gaat sneller) translating to mean "drive slower to go faster" (thanks for the translation, Mark Wagenbuur) or in other words, driving more slowly, but more smoothly means you get to your destination in a more reliable time. In the context of this roundabout it also means drivers can see people walking and cycling in good time and by easing off their speed a touch, they barely have to stop too. 

Here's another video from the excellent Ideas with Beers series which looks at the scheme and there's a talk about before this piece the off-street trials which took place in 2013 and which I experienced in October of that year (yes, it took that long between someone testing it and someone building it).

Would I build this type of roundabout in more places? That's a firm "depends". Cambridge was probably the right place for this scheme because of the fact that lots of people cycle in the city and people who drive there should expect people cycling, although the junction doesn't sit within a network of protected cycleways which is a significant disadvantage to a proper shakedown.

Care should always be taken when copying other countries' designs because the rules and design approaches have subtleties. On the one hand, the blogger David Hembrow suggests we should go for designs where cycle traffic gives way and his blog posts on the subject are vital reading for designers and campaigners alike because it is an approach we can easily copy in the UK. On the other hand, many parts of the Netherlands have decided to push on with the version giving cycle traffic priority in all urban situations and the blogger Mark Wagenbuur explores that in his blog post.

Where the cycle priority design has been chosen, this has been because a municipality have designed to give more cycle priority everywhere and to that extent, priority at roundabouts is consistent and something drivers should be able to anticipate. In the UK, we will have to pick the right locations and unless the geometry is controlled as well as the Cambridge example, we will build risky layouts that lull people cycling into a false sense of security.

There is only one team in the UK which has built a Dutch style roundabout and that's the Cambridgeshire team. I hope that in due course we'll get some longer term learning and study information from the scheme and I'd love to be involved in the design of one myself, so long as it is in the right location. I also think we need to build some of the other type because these can be safely rolled out in far more suburban and rural situations. 


  1. Very interesting, thanks.

    I think cycle priority is important if we are too encourage modal shift. I doubt it would be dangerous in practice, as people on bikes would be naturally cautious and local drivers would soon get used to it.

    My highways authority are always looking for excuses not to change the status quo, and to keep rolling out the red carpet for motor vehicles. They would jump on the suggestion that cycle priority is 'ooh, much too dangerous.'

    1. This layout is not going to be usable everywhere. The Dutch only use it in built up areas - the rural (and I would argue suburban in a UK context) has cycle traffic give way, but in practice, you rarely stop because you can see the traffic and adjust the pace. It's worth reading Hembrow's concerns in this regard.

  2. What about the one at Crystal Palace that opened three years ago? Not perfect by any means but was the first to use the cycle/ped priority Zebra layout.,-0.0747989,3a,75y,160.62h,82.34t/data=!3m6!1e1!3m4!1s54WltLD9Vq4DtG-z-xIF3A!2e0!7i16384!8i8192

    1. I've not had the chance to look at this one, but it's not Dutch. It's some UK style bodging albeit with cycle tracks.

  3. That is an interesting arrangement in Crystal Palace. Is the roundabout actually a roundabout? Looks like a hybrid of a mini-roundabout and a conventional roundabout, does TSRGD allow this now? Also the signing for the shared path separated path do not look correct, unless you can ride on the footpath as well as the separated bike path.

    1. I've not visited, but it does look like a bit of a bodge up