Roundabout safety for cyclists and why Cambridge's new 'Dutch' roundabout is not what it should have been

This is not the Cambridge roundabout. It's an example of a different
design, the safe roundabout. This design is much more tolerant of
driver mistakes and results in a far lower rate of cyclist injuries.
Please read my blog post about this design and watch the
accompanying video as both of those describe how this
design keeps cyclists safe.

Cambridge in the UK recently opened a "Dutch style" roundabout on Fendon Road to replace another roundabout which had a poor safety record for cyclists in the city. People keep pointing this out to me. I think it's perhaps time for a response.

The design chosen is that which I have consistently recommended against. Why do I recommend against it ? Because it has a poor safety record here in the Netherlands. It has a safety record which is not very different to an uncontrolled crossing or having no cycling facilities at all on a roundabout, which was the situation in Cambridge before this new design was built. I am not convinced that British drivers are better trained or will behave in a safer way on roundabouts than Dutch drivers and therefore I am also not convinced that it will be safer to use this design in the UK than it is here. Dutch drivers have been trained for decades to expect to give way to cyclists under some circumstances and they have also had decades to get used to this type of roundabout, yet it remains unsafe in the Netherlands. Why should we expect this to be different elsewhere ?

Now you might wonder why all my emphasis so far has been on drivers. There's a simple reason. The danger comes from motor vehicles which are faster and heavier than any cyclist. That's why injury rates for cyclists are higher at roundabouts with more cars. Remember always that there is no design of roundabout which is built for cyclists. If it were not for cars then we would have no roundabouts at all and cycling would be all the safer for it.

Dutch research into roundabout safety

Dijkstra's research into roundabout safety in the Netherlands in 2005 is one of the most referenced articles about this subject. Here's a link. It's written in Dutch and having seen the mess that bad machine translations make of this and similar documents I suggest that if you can't read the Dutch then you're best off going no further than the abstract and my explanation below.

The research drew its conclusions from looking at three different earlier studies each of which looked at large numbers of roundabouts. They're well run studies and the people making them attempted to compare like with like. There was no attempt to study only a subset in order to favour a conclusion already drawn by any of the authors. Dijkstra's article is often used by proponents of priority on roundabouts, though I wonder if they actually read it all the way through. It's very clear about the danger caused by giving cyclists priority on roundabouts.

This graph compares the number of serious cyclist and moped injuries per year (Y) at roundabouts of differing types with differing motor traffic intensity (X). The green line shows the effect of a cycle-lane around the roundabout, which has been known to be dangerous for decades and is recommended by no-one  The black line shows a roundabout with no facilities, cycling taking place on the road amongst cars. The blue line shows the effect of cycle-paths around roundabouts, but this is an average as it is not specified which roundabout design or priority rule it refers to, which is a problem as I'll discuss later.

This graph looks a lot like that above, but it includes all serious injuries in all vehicles, not just those which occur to cyclists. However it is clear from comparing this graph and the one before that roundabouts are, generally speaking, far more dangerous for cyclists than they are for drivers. The relatively small number of motor vehicle occupants who are injured at roundabouts pushes each of the lines upward a little. The effect is especially obvious on the lower, blue line as in this case motor vehicle occupant injuries become dominant as traffic intensity increases. But comparing the two graphs does not make a clear-cut case for all roundabouts with cycle-paths because there is no distinction made between two very different roundabout designs discussed later by Dijkstra.

Three different studies are referenced by Dijkstra, that of Van Minnen/CROW (1998), Weijermars (2001) and Gerts (2002). All three of those studies showed that "with priority" roundabouts are substantially more dangerous for cyclists.

Three studies are summarized by Dijkstra. All studies show worsened safety with cyclist priority ('in voorrang') at roundabouts. Crashes (ongevallen) are between 1.75x and 2.9x more common and injuries resulting in death or hospital treatment (slachtoffers) are found to be between 3x and 6x more common. Gerts' study only reported crashes and not injuries.

Some of the data in the document, such as this example, show all injuries and not just cyclist injuries. Overall, a junction with cyclist priority ('in de voorrang') causes about three times as many injuries.  About as many motor vehicle occupants are injured on the two different types of roundabouts, the difference is made by the radically different results for cyclist safety. See the next table.

The same data from Weijemars is used here, but just the figures for cyclists and mopeds are included.

This table shows the number of roundabouts in total, within urban areas, with cycle-paths, with cyclist priority (470), without cyclist priority (314). These numbers come up repeatedly.

Estimated annual hospitalizations of cyclists and moped riders (on the cycle-path - now largely replaced by e-bikes) in the Netherlands due to crashes with motor vehicles on urban roundabouts. There are about 50% more roundabouts with cyclist priority ('in de voorrang') but they cause ten times as many serious injuries as the safe design of roundabout ('uit de voorrang').

Note that Dijkstra used data from Gerts who referred only to roundabouts which strictly followed the CROW design standards. By doing so both Gerts and Dijkstra tried to exclude potentially worse results which could have come from priority roundabouts which didn't follow the standards. This turned out to be less important than was expected because Gerts found that there was no statistically different result for roundabouts which followed the CROW norms vs. those which did not (bottom of page 13). Also read pages 34 and 35 where this is confirmed. i.e. The difference in safety between differing roundabouts with cycle-paths is almost entirely due to the priority rule. That is confirmed on page 36 where the conclusion is made that there is a significant link between priority and safety.
A note about 'mopeds'. Most of the data lumps cyclists and mopeds together because mopeds are not actually very common. They make up around 1% of the total traffic volume. As a result, I don't expect that their presence here makes much difference to any of the results. Low power mopeds which theoretically are limited to around 25 km/h on the cycle-path are losing ground these days to electrically assisted bikes which travel at a similar speed. Many Dutch people really don't like mopeds, but they do seem to like e-bikes which are now far more numerous. The two modes are quite similar from a safety perspective. There does seem to be an indication that 'with priority' roundabouts are more dangerous for faster cyclists (moped, racing bike, e-bike) who are more likely to surprise drivers because their speed makes them more difficult for drivers to spot, hence the idea that they suddenly appeared "from nowhere" over the driver's shoulder. Faster mopeds (limited to 45 km/h) are banned from urban cycle-paths so are not of interest here.

Comparison with a non-signalled crossing
In order to find a point of comparison for the effectiveness of substituting one type of roundabout or another, comparisons were made of 177 locations where non-signalled crossings ('voor, kruispunt') were converted into roundabouts ('na rotonde').

Note that this is not a comparison with traffic light junctions. That's a completely different story which I have addressed elsewhere: well designed traffic light junctions which separate cyclists in time and space from cars create an almost completely safe space for cyclists and as a result have an excellent safety record in the Netherlands. But they are not discussed by Dijkstra. These comparisons are between roundabouts and the straightforward non-signalled crossings without roundabouts or traffic lights which existed in the same location before they were built.

The comparison over time with non-signalled crossings in the same location across 177 junctions gives us a very good idea of the relative danger creating by giving cyclists priority at a roundabout.

Roundabouts are highly effective at preventing motor vehicle occupant injuries, reduced by 80% on average over the previously existing crossing, however for cyclists they are far less effective. Compared with non-signalled (no traffic lights) road crossings, Dutch roundabouts on average only lead to around a halving of cyclist serious injuries. But this statistic is deceptive because both the 'with priority' and safe roundabout designs have been mixed here to create an average.

In this table they've been separated and we if we consider only the safe roundabouts where cyclists do not have priority ('uit de voorrang') then we see a significant 87% reduction in the number of injuries vs. a non-signalled junction.

By comparison, if we consider only the roundabouts where cyclists do have priority ('in de voorrang'), the improvement in injury rate over a non-signalled crossing is just 11%. i.e. priority for cyclists on roundabouts results in nearly eight times as many cyclist hospitalizations as occur at safe roundabouts when replacing non-signalled junctions. But carry on reading...

The simple conclusion to reach here is that 'with priority' roundabouts achieve about an 11% improvement in safety while safe roundabouts achieve an 87% improvement in safety, making them eight times safer. However it's not actually that simple. Over the same period of time, non-signalled crossings across the country became on average about 10% safer (Dijkstra last paragraph of page 10) so we should perhaps reduce both outcomes by this amount. That would imply that there is actually almost no significant difference in safety between an non-signalled crossing and a 'with priority' roundabout while a safe roundabout achieves about a 77% improvement in safety for cyclists.

How safe are 'with priority' roundabouts in reality ?

This blog post began with one of the first graphs from Dijkstra which showed the relative safety of cyclists using cycle-paths and cycle-lanes around roundabouts with cycling on the roadway on the roundabout itself. Unfortunately, that graph did not distinguish between the different types of Dutch roundabout which include cycle-paths. However later in the same document with the discussion about replacement of non-signalled junctions, Dijkstra calculates the relative safety of roundabouts with and without priority, and we see that the 'with priority' cause nearly eight times as many excess cyclist injuries as the safe roundabout design. I find it unhelpful that both roundabout designs are presented as one item in that graph as they really are not the same.

Below you'll find a modified version of the same graph showing the likely real-world safety of 'with priority' roundabouts vs. the average for all cycle-paths on roundabouts, cycle-lanes and cycling on the road:

The red line shows what the probably injury rate is for roundabouts with priority cycle-paths in the Netherlands. The blue line is an average for all roundabouts with cycle-paths. A line which represented only safe roundabouts would be lower than the blue line, especially in the first half of the graph.

You'll note that up to around 10000 vehicles a day there is no great difference between the black line, showing the rate of injury for cyclists riding on the road, the green line showing a cycle-lane painted around the perimeter and the red line showing the injury rate for cyclists on 'with priority' cycle-paths. Therefore swapping between a roundabout design where cyclists ride on the road to a design where they use a priority cycle-path should not be expected to bring an improvement in safety. The only option which always looks good is the blue line showing as an average for all roundabouts with cycle-paths, which is skewed downward by the greatly improved safety of the safe roundabout design over the 'with priority' design.

Explanation of the red line: Over half of all urban roundabouts in the Netherlands gave cyclists priority when Dijkstra's graph was created. He found that on these roundabouts about eight times as many injuries per year could be expected. i.e. the corrected data for with priority roundabouts should be at about four times the level of that for the safe roundabouts. The red line which I have added to the graph is at approximately three times the height on the Y axis of that for both types of roundabout combined. This places it at approximately at the level we would expect to see if the two different types of roundabouts had been  treated as two different cases.

Explanation of blue line shape and stippled red: The blue line, for all roundabouts with cycle-paths, has a rather unusual shape, with a peak at around 10000 vehicles a day before dipping downward and rising again with motor vehicle intensity. I believe that this is caused by priority roundabouts causing the vast majority of crashes and injuries but being built mostly in places with lower motor vehicle intensity. As a result, the blue line is pushed upward in the first half of the graph by crashes on 'with priority' roundabouts, but I think the second half of the blue line is made up to a higher extent of data for safe roundabouts. I used a stippled red line from ~10000 onward because it's likely that it is no longer reliable past this point for the same reason. Unfortunately the separate data is not available so that I can test this hypothesis.

Politics

Back in 1998, SWOV's own research already demonstrated a worse safety record for 'with priority' roundabouts. Their research indicated that 52-73 extra cyclists would find themselves in hospital with serious injuries each year if that design was used. Despite this concern, a political decision was made to go along with a standard recommendation that cyclists should always have priority on urban roundabouts. This happend after they were given two re-assurances: first that the new standards advised by CROW would be applied everywhere and second that introduction of these standards would result in improved safety for 'with priority' roundabouts.

Unfortunately, the expected safety improvement was not realised. This was not merely because the guidelines still were not followed in all cases, but because it was discovered that the guidelines didn't actually have a measurable effect on safety even where they were followed. In an appendix on pages 29 to 35 of Dijkstra ("Voorrang voor fietsers: effect van vormgeving?") it is shown statistically using data gathered from many real world roundabouts spread across the country over five years that there is no detectable difference in safety between 'with priority' roundabouts which adhere strictly to the CROW guidelines and those which do not. Therefore it would seem that roundabouts with significant differences from the norms (e.g. different radii, crossings too close to the roundabout, inadequate road markings, allowing bidirectional cycling around the roundabout etc.) were not worse from a safety perspective at all. The research suggests very strongly that exactly following CROW's guidelines is not important for safety at all. Just one thing makes roundabouts with cycle-paths dangerous and that is giving cyclists priority.

Since the decision was made to go along with the "with priority" guideline in urban areas, the number of roundabouts in the Netherlands has tripled. For that reason we can now reasonably expect that instead of 52-73 extra cyclists receiving injuries resulting in hospitalization or death each year that there are now between 150 and 210 more than would have been the case if the safe roundabout design (used all over Assen with extremely low injuries as a result) had been standardized upon across the entire country.

The CROW argument that roundabouts with priority are "slight less safe" than the safe design was based upon the 52-73 extra casualties being only between 1.8 and 2.5% of the total. Unfortunately, with their number having tripled, we can now expect that these dangerous roundabouts account for between 5.4% and 7.5% of cyclist casualties per year, which is certainly not insignificant. Given that after a period of decline, Dutch cyclist deaths are now rising once again, this is something we should be looking at more closely. We already know how to reduce injuries on roundabouts by 87%. We just have to switch to building the proven safe roundabout design.

Cambridge

So now back to Cambridge. Why did that city outside the Netherlands adopt a design has been proven to cause excess injuries and deaths in the country where it came from ? Why are they following a decision which was made in the Netherlands for political reasons and not based on safety ? Personally, I think they were extremely badly advised.

Valkenswaard roundabout visited in 2006. Not a safe design.
See statistics. This roundabout does not conform 100% to
CROW standards, but as you can read above, we now
know that it probably wouldn't make a difference if it did.

Now I take a little responsibility for this because I used to live in Cambridge, I was a member of the Cambridge Cycling Campaign who campaigned for Dutch style cycling infrastructure to be built in that city, and I organised study tours in the Netherlands for members of the campaigning group and people working for the council. Indeed, on the first of these study tours, way back in 2006, I was myself enthusiastic about the cyclist priority design of roundabout and I showed it to people from Cambridge.

However my enthusiasm for priority roundabouts didn't last long after I moved to the Netherlands, experienced near misses on these designs, learnt Dutch and read Dijkstra's and other studies of roundabout safety. I change my mind when presented with contrary facts and it's simply not possible to continue to believe that these designs are safe when they clearly are not. That is the reason why I promote the safe design of roundabout, especially in countries outside the Netherlands.

The advantage that the safe roundabout design has is of complete predictability for the cyclist. As a cyclist you can take control of your own safety. While mistakes made by drivers on priority roundabouts where the driver does not cede priority often result in crashes and cyclist injuries, drivers on safe roundabouts who make errors typically just slow or stop when they need not have done. This can actually be slightly annoying for a cyclist who has adjusted their speed to slip across the road before or after any given car, but it's a safe failure mode which doesn't result in injury.

There is also the potential difference between British and Dutch drivers. I've not only cycled but also driven in both countries and I think the ability to drive safely is quite similar between the two countries. However there is a difference in behaviour in that Dutch drivers typically drive more slowly, at least on minor roads and in towns, and that there is less aggression. This is probably also a function of the unravelling of routes which keeps drivers who are minutes late for their destination from making through journeys near cyclists. They are also used to the idea of ceding priority to cyclists on roundabouts and elsewhere, and most people here do cycle. What effect this difference in driver behaviour will have on a roundabout design which requires drivers to cede priority in order to ensure cyclist safety is currently unknown.

Unfortunately the mistake in Cambridge goes far beyond just choosing a poor and dangerous design of roundabout. Their ambition unfortunately went no further than substituting one roundabout design for another and it is now being heralded as a victory for cycling before we even know whether it turns out to be safe in this location. In reality there is no roundabout design which has ever been built for the benefit of cyclists. They're all just ways of trying to address the problems caused by motor vehicles.

Most road junctions in Dutch residential
areas look something like this. Much
more common than any traffic light
or roundabout design, a non-signalled
junction in a residential area, with 30 km/h
speed limit, raised table, small corner
radii, and most importantly it's not a
through route for motor vehicles.

Addressing the problems of motor vehicles could have been done in many other and more effective ways. The roads leading to the location of Cambridge's new roundabout are places where people live. Residential streets which have for years endured high traffic volumes. If they had their usage changed so that they no longer had to support that through motor traffic (already done on a tiny scale in Cambridge) then the roundabout probably wouldn't be required at all. A simple non-signalled junction but with very cars, or if a stream of traffic was required to flow between two arms of the junction perhaps a signalled crossing, would have resulted in a better outcome for cyclists.

You could have asked...

There are few people who have lived, worked and cycled on an everyday basis in Cambridge for more than a decade and who have then done the same in a Dutch city for more than a decade. Fewer still who have written about cycling for decades, about cyclist roundabout safety and made suggestions for how countries outside the Netherlands can best learn from the Dutch experience regarding roundabouts and other infrastructure. Still fewer who have gone to the effort of learning Dutch, reading the research and trying to advise on the basis of that research, and I would guess that also bringing people from the council and the local cycle campaigning group in Cambridge to the Netherlands in order to demonstrate to them the pros and cons of different roundabout designs amongst many other things on top of those other things would make me pretty much unique. I'm also not hard to find.

So do you think anyone from Cambridge ever thought to contact me about their new roundabout ? Of course not. Actually that's a bit unfair. A couple of people on the periphery who were concerned about the direction in which that was going did make contact and I have heard from them how what I'd written was dismissed rather rudely. But why ? Did they have some other local expert who could read the Dutch documents in depth and translate them ? Did they not believe the stats therein ? Did they expect that a design which is relatively dangerous in the Netherlands with Dutch drivers would somehow be less dangerous in the UK ?

I of course don't expect any answers. But it's a shame. I could have helped. I fear that Cambridge will regret what has been done. Not now. Not soon. It'll take a while before you have stats - the Dutch research on which I based my advice was itself based on the stats from many roundabouts over many years. The stats above are based on up to 940 rotonde-jaren, or roundabout years. These results have not been cooked up after just looking at a single location for a few weeks.

Conclusion

I am left with a fear that what Cambridge has done is merely to replace one dangerous roundabout design with another. It's a pity that they have done this because it's been done with such a lot of publicity and this may tarnish the concept and make it more difficult to adopt a better design elsewhere. Britain's cyclists need safe infrastructure. It's high time that they got it instead of ineffective projects like this example. However this is just one junction in one city of a country of many millions of people. It won't in itself make a huge difference one way or the other. No single junction ever could do that.

What is required, in Cambridge and elsewhere, is to start looking at the bigger picture. It is a mistake to think that any real change can result from a piecemeal one junction at a time approach. The UK, and everywhere else, needs a complete grid of effective safe and attractive cycle-paths in order to enable efficient go-everywhere cycling. The Netherlands is fabulous for cycling not merely because some of the roundabouts are safe (as you can see above, some certainly are not). An holistic approach makes the difference. There is nothing new and novel about any of this, it's been known for forty years.

Planning occurs in the Netherlands on a much greater scale than in the UK. There are traffic circulation plans which limit the effect of motor vehicles on residential areas and direct cycle routes. Almost all roundabouts form part of a plan which removes motor traffic, especially through motor traffic, from locations where cyclists need to be to make everyday journeys. This makes even less safe designs safer. But removal of motor traffic can even result in a much bigger prize: the removal of roundabouts and traffic lights altogether from cycling routes. Cyclists don't themselves need either of those types of junctions. They are not actually for us, but exist only to moderate motor traffic. There exist very good traffic light designs which benefit cyclists and roundabouts which do likewise but in both cases these things should only be built where there is no choice. i.e. where it's impossible to get rid of the motor vehicles. Cyclists are always better off without big road junctions. This has happened on a large scale at least around the centre of most Dutch cities, spreading outward from the centre in many cities and into the renovation of old suburbs and the design of new suburbs. The process did not begin by changing the design of a single busy junction which will remain busy, but then making a lot of noise about it as if a great change has been achieved.

The piecemeal approach, resulting in years of little or no real action and the effect of such small forward steps as occur usually being swamped by backward steps elsewhere, is precisely why people in the UK have gone from saying that their country is 20 years behind the Netherlands to 40 or 50 years behind. It's only possible to catch up by doing the hard work required to make things better, consistently over years. This is something which no country can afford not to do: when all things are considered, it's cheaper to build cycling infrastructure than it is not to build it.

Update May 2023
Three years later we now have reported collision data for the Cambridge roundabout. In the three years since the roundabout was rebuilt as "Dutch" style there have been 10 collisions, including three which caused serious injury. In the three years before the change there were just six of which none were serious.

I'd been advising people in Cambridge about roundabout designs for well over a decade before they ignored my advice and chose to build this dangerous design instead. They now have injured cyclists as a result of their choice. I take no pleasure in saying that "I told you so", but I did tell them, repeatedly, and the result that they now have is just what I predicted.

A traffic light design which enables safe turns across traffic for everyone

Poor cycling infrastructure designs struggle when it comes to allowing cyclists to make turns across traffic (a left turn in continental Europe / USA) in a manner which is both convenient and safe. In some cases, designers simply don't really try and this results in such abominations as centre cycle lanes leading into advanced stop lines (bike boxes) on the ground. There are also examples of designs which are promoted quite hard but which don't really help people to cycle because they make turns inconvenient, dangerous or in some cases both inconvenient and deadly dangerous.

The new junction on the day it opened. The cycle-path widens
to nearly 4 metres in width to accommodate cyclists going
straight on as well as those turning left. Note traffic lights
for cyclists. The green for straight on is almost always lit.
This only goes red to allow cyclists to emerge from the right.

On the other hand, there are also good examples, though these are not necessarily so easy to find. Some designs improve both safety and convenience for cyclists. One solution for traffic lights which I'm particularly enthusiastic about because it has a very good track record is the simultaneous green junction, however there is no one design of junction which fits all locations and other good designs are possible.

This new junction demonstrates a very good way to design for asymmetric cycle traffic. In this case, almost all cycle traffic heads head straight on across the junction and they have a nearly full time green light. Only the relatively small number of cyclists who turn left are stopped by the traffic light in the video and this introduces only a short delay until it can stop all conflicting motor traffic and remove all danger from the left turn.

Crossing in the opposite direction is also convenient. Note that
right turning motor traffic is stopped when cyclists have a
green light and all straight on motor traffic is to the left of the
thick white line. There is no conflict in this direction either.

The old junction in this location featured on my blog in 2012. This already worked well, but it stopped cyclists heading straight on relatively frequently and did not allow for a left turn to be made by bicycle. The old junction was built on land and did not incorporate a bridge. The new bridge had to be built to enable re-opening a canal which was filled in decades ago and the new junction is on top of that bridge.

The Weiersbrug is one of six new bridges in Assen which began construction at the end of 2014. Five of those bridges are now complete and one remains to be built. I've been critical in the past of some aspects of the huge FlorijnAs project in Assen, but it has also brought improvements for cyclists in some locations, such as here.

Another view from another angle
This junction really does work very well for cyclists. The delays for a green light are minimal, and this partly is the result of the lights defaulting to red for everyone (cars, bikes, pedestrians) when there is little traffic and responding almost immediately to whoever comes along first. This video shows what it's like to go through this junction twice on a Sunday morning when there are few people about:
 

An older implementation of the same idea, with inadequate
lane sizes and not enough space to make the turn. This was
recently removed from the area around Assen railway station.

Not a new idea, but a top class implementation
The idea of cyclists waiting to turn left at a traffic light in this way is not in itself new. However, this new junction brings a level of refinement which makes it comfortable to use. This new junction works far better for left turning cyclists than did the an older implementation of the same idea which was recently removed from the railway station area of Assen.

The junction shown in the video with a blue arrow showing the route taken by left turning cyclists in the video. While cyclists make this maneouvre or any other across the junction which could result in conflict with motor vehicles, red traffic lights hold motorists to remove the conflict.

Book now

Come and see
This new junction opened in May on the second day of a follow-up study tour. There is new cycling infrastructure to see every year in Assen and the programme changes each year to allow for what has changed. Future study tours, such as the tenth anniversary tour in September, will feature this junction amongst other pieces of new infrastructure.

True mass cycling, inclusive of all members of society, including children, older people and those with disabilities and where everyone makes all types of journeys by bike, is only possible with the very best cycling infrastructure. Be inspired by the best, not those things which really ought to be ignored.

Safe cycle priority road crossings

I've covered several types of road crossing for cyclists in the past. Those with traffic lights, where cyclists have to wait for motorists but can stop in the middle of the road, those where there is equal priority between cyclists and motorists. Sometimes it's possible to give cyclist priority over roads when cycle-paths and roads cross but this can only be safely achieved if certain conditions are met. It is not enough simply to put up a give-way (yield) sign and expect that drivers will obey it.


Driver behaviour is more effectively controlled by road layout than by signs or speed limits. In order for it to be safe to give cyclists priority at a crossing, the speed of cars on the road needs to be controlled and traffic volumes need to be low. The junction needs to be designed such that it gives obvious visual priority to cyclists, and sight lines need to be good enough that drivers and cyclists can see each other and respond accordingly. This is not the same concept as "making eye contact". If people driving and cycling are surprised by the other party because they cannot see them in time then they are less likely to be able to respond safely.

First example in the video. Cycle priority crossing of a minor road. 30 km/h speed limit on the road, raised table starts 20 m and 14 m away from the crossing. Bend in road naturally slows cars. The cycle-path is three metres wide and runs at a distance of six metres from the parallel road.

Second example. This road has a 30 km/h speed limit, but it is a much busier road than the other two, providing a route by car to local shops and other facilities. Raised table starts 5 m and 12.6 m from the cycle crossing. Bend in road naturally slows cars. Cycle-path is 3.5 m wide and runs perpendicular to the road.

Third example. The raised table almost doesn't exist in this case and there is no bend in the road so drivers pass over this crossing at far higher speeds than the other two. Note how drivers may not be able to see cyclists coming from North or South until they are close to the crossing due to being obscured by buildings and vegetation and then there is a chance that a driver will misinterpret the intentions of a cyclist so not slow down for them. Note also how the curves on cycle-paths, especially North of the crossing, are far less helpful for cyclists than the other two examples. Cycle-path is 3 m wide and at the point of the turn it's just 3 m from the parallel road.

While the third example is the one which I believe is least satisfactory (see the video for why), collisions between cars and bikes are only recorded as having happened at the second example. There is a rational explanation for this. The second example is located adjacent to the local facilities of a suburb (shops / doctor / health / church) and this results in considerably more cycle and car traffic than the other two which located within residential streets. Three collisions with cyclists occurred over the 2007-2012 period at the second example, one of which caused an injury.

Curve radii and approach visibility
The recommendation of the CROW Design Manual for Bicycle Traffic for curve radii is particularly relevant to cycle priority crossings. The manual says that on curves with below 5 m radius, "cycling speed drops below 12 km/h and the cyclist has to work hard to remain upright" and suggests appropriate curve radii as follows:

1. cycle connections that form part of the basic network should have a radius of greater than 10 m, geared to a design speed of 20 km/h;
2. cycle routes and main cycle routes should have a radius of greater than 20 m, geared to a design speed of 30 km/h

Note that this refers to cycle-paths having a design speed of 30 km/h. Cycle facilities should not be designed to slow cyclists, but to enable efficient cycling. The first two examples above conform to this recommendation, while the third, especially when approached from the east, does not. This causes a problem for cyclists and motorists.

CROW recommended visibility at crossings by road width (crossing distance) and speed.

The requirement for approach visibility should also be noted. Take into account that these speeds are 85th percentile speeds in actual use, not merely the posted speed limit, and that the required sight lines more than double in length for any crossing of a 50 km/h road vs. a 30 km/h road. Also note that wide roads require more visibility than narrow roads because crossing times are longer.

All the roads shown in the above examples are under 7 m in width and in all those cases there is a 30 km/h speed limit so sight lines of about 50 m in length are required. All three examples include additional measures to control speed. In the first example, the posted speed limit and additional measures are adequate for a 50 m sight line. In the second example they are marginal (though helped enormously by the curve in the cycle-path which places cyclists in a more visible position and the curve in the road which slows drivers). The third example does not meet the requirements because the speed of cars is excessive and the sight-lines are not long enough.

Related: Note that it has been understood for many years in the Netherlands that posting a lower speed limit is not enough to ensure lower speeds.

Difficult to retrofit
It is very difficult to successfully retrofit crossings of this type because existing streets are often too straight, existing paths often not visible enough. While cycle priority crossings are fairly unusual in the Netherlands, retro-fitted cycle priority crossings are even more rare. All the examples of priority junctions in Assen were designed as integral parts of the road design. Those used as examples in the video and images above date from when those parts of Assen were designed and built in the late 1970s through to the 1980s.

Cycle priority is not the same as pedestrian priority
People sometimes ask why cyclists are not given permission to cross with priority on all pedestrian priority (zebra) crossings. There are good reasons why this should not be so. In many locations, it would be difficult for a cyclist to be The risk of a cyclist emerging quickly from behind a building or because there are inadequate sight lines. Cyclists are much faster than pedestrians and they require space in order to make a turn.

This crossing of a busy road gives priority for pedestrians over both cyclists and drivers. but there is no place within this layout to provide a safe priority cycle crossing. In any case, any cycle crossing would be better slightly further North on desire lines.

This location has a parallel cycle and pedestrian crossing. Pedestrians have priority while cyclists do not. This is a relatively busy through route for cars with a 50 km/h speed limit. As a result a cyclist emerging at speed from the side roads may appear in front of a driver before the driver has had an adequate chance to response and therefore there is too high a chance that a driver won't stop in time. But they have much more time to react to a pedestrian due to the slower speed of pedestrians.

In this location cyclists have priority over side road crossings which are parallel with the main road. These roads have 30 km/h speed limits and speeds are further reduced by the junction, the small corner radii and the raised tables. However only pedestrians have been priority over the 50 km/h main road.

At a very large busy junction, this example joining the 70 km/h ring road to a 50 km/h main route out of the city, neither cyclists nor pedestrians are given priority over motor traffic in any direction. On a road like this with many lanes of traffic, higher speeds and much to look out for it would be dangerous to give priority to cyclists or pedestrians. This junction is too large and busy to be a "protected intersection". While it could have seen implementation of a simultaneous green junction, instead there is a more conventional traffic light junction here next to which cycle path green lights are synchronized with motor vehicle red lights where conflicts would otherwise occur. Priority can be given for cyclists and pedestrians by other means. In other locations in Assen this is done by use of tunnels and very quick reacting light controlled crossings. Two cyclists were injured here. One due to a single sided collision with street furniture, the other due to ignoring a red light.

Hook turns
A possible solution which people sometimes think of to the problem of turning across traffic is the hook turn. We have precisely one example of this in Assen. It's a relic from the past which has somehow survived on a quiet residential street and it's shown in the photo below. Note that the hook starts with a cycle-path in the top right hand corner of the image and continues more than 60 metres to the junction which it serves in order that it could provide a gradual enough transition for cyclists. The crossing is then assisted by a large raised table. Despite all of this, it's actually quite awkward to use. It perhaps made a little more sense decades ago when this was a busier route, but it certainly doesn't help in this situation now. I don't recommend this type of infrastructure.

A generously proportioned 60 metre long hook turn assisted by a raised table. But it's still awkward to use.

"Visual priority" The Alternative Department of Transport blog recently coined the phrase "visual priority" to refer to where priority at a crossing is indicated by the design of the street and not merely by signs. The red surfacing continuing through each of the junctions shown in the video at the top of this blog post is a good example. I like this term, it's concise and obvious, so I have used it too. Most examples of crossings in the Netherlands benefit from good visual priority. Of course, good visual priority is only one factor. In itself it is no guarantee of success. As you will see from the video, the third example of a junction with a short raised table which coincides only with the crossing itself is not successful at slowing cars even though the visual priority is good. Junctions must also encourage safe behaviour by other means, such as use of bends on roads and level changes using a raised tables to slow drivers, bends on cycle-paths to improve sight lines, and we must of course realise that there is no one-size-fits-all solution. The majority of junctions are not suitable for a cycle priority treatment for reasons of sight-line or traffic speeds and volumes.

Real examples in real-life usage

It's not possible to completely understand infrastructure like this from reading blog posts and watching youtube videos. On our study tours we demonstrate real life examples.

The best roundabout design for cyclists. The safest Dutch design described and an explanation of why this is the most suitable for adoption elsewhere

Roundabouts are often disliked by cyclists because using them by bicycle can be fraught with danger. When riding on a roundabout, you rely upon drivers seeing you on your bike. There is a tendency for motorists to look right through cyclists while looking for other motor vehicles, hence the frequency of "SMIDSY" incidents. However none of this has to be the case. The best Dutch roundabout designs do not cause significant danger for cyclists. But note that not all Dutch roundabouts are created equal. There are big differences in the safety of different designs of roundabout used in the Netherlands, and not all advice from this country emphasizes the safest design.

This blog post is mainly about this roundabout. It's an urban roundabout used by a large volume of traffic including pedestrians, cyclists, cars. buses and trucks. It's interesting because of its very good safety record - just four crashes in five years, all minor car-car crashes, none of which involved a pedestrian or cyclist and none of which caused an injury to anyone.

There is a common misconception held in other countries that Dutch roundabouts are safe for cycling due to their geometry, but actually the roundabouts of Assen, just as other Dutch cities, vary enormously in design. The geometry of Dutch roundabouts is not the common factor which makes them safe. What makes them safe is removing cyclists from harm's way and the safety of different Dutch designs comes down very much to how well they keep cyclists away from potential injury.

In the Netherlands it is not expected that cyclists should be mixed with motorized traffic on roundabouts. There is always a cycle-path or lane of some form. While cycle-lanes around roundabouts are not generally thought to work well. there are two opposing views on how these cycle-paths should be designed. One view holds that cyclists should have priority across each road leading to the roundabout, the other holds that it is dangerous for cyclists to have this priority. The current recommendation¹ is for roundabouts within towns to be the "cyclists priority" design while roundabouts outside towns give priority to motor vehicles, and many towns in the Netherlands have adopted these recommendations. However, not all towns have done this and Assen is one of the hold-outs.

Adverse camber on the roundabout
itself encourages slow speeds, which
improves safety for all users. Longer
vehicles have to use the red surfaced
raised area which further increases
the camber.

The roundabouts in Assen have a particularly good safety record even by comparison with other Dutch roundabouts in other Dutch cities. During the five year period between 2007 and 2012, there were just two cyclist injuries at all the 21 roundabouts combined. The impressive safety of Assen's roundabouts is in part due to the city having ignored the recommendations made in the CROW manual and having retained motorist priority on each of the crossings. This may sound as if it makes cycling less convenient, but we have not found this to be a significant problem. It's rare that a cyclist must put their foot down and stop. It is more often the case that cyclists adjust their speed and merge through any traffic which is crossing the roundabout. That is actually much the same as a cyclist would do on approach to any other roundabout design. In reality you must give way at some point or another on entering any design of roundabout. All that changes between these two designs is at which point you must give way.

The design of Assen's roundabouts results in crossings of roads always being at 90 degrees and the 90 degree crossing point being where cyclists must give way. This makes it easier for both drivers and cyclists to see what is happening in all directions of interest. This roundabout design also makes sight-lines longer which gives more time to react, more time to adjust speed so that it's almost always possible to cross without stopping. Both of these result in safety advantages over the other Dutch roundabout design which has an annular ring.

With this design, a significantly higher degree of safety is achieved in exchange for perhaps a very slight decrease in convenience. But the decrease in convenience is really not large as people often fear, especially when we take into account that cyclists can cross safely in both directions around roundabouts where the crossings are at 90 degrees. This saves time because it's possible to take a short-cut across the junction and reduces exposure to risk as we need cross only one arm of the roundabout to make a left turn instead of more if we had to ride all the way around the roundabout to make a left turn.

Please do watch the video as it demonstrates clearly how efficient and safe this design is. Note how at the start of the video it is demonstrated that it is possible to travel across this roundabout by bicycle without adjusting one's speed at all. This would not be the case with a "cyclist priority" roundabout or by cycling on road as in both cases a reduction of speed would have been necessary at the point of reaching the roundabout.

The video shows one of the busiest roundabouts for cyclists in Assen and demonstrates why it is both safe and convenient for cycling. Only four collisions of any type were recorded here in five years, and they were all of the "fender bender" variety, where one driver shunted another at low speed on the way on or off of the roundabout. No cyclists or pedestrians were involved in any way in any of these minor collisions and there were no injuries to the drivers either:

This is even more important for other nations

DO NOT COPY THIS EXAMPLE
This photo has featured on many blogs
but they unfortunately picked a bad
example. This is the annular ring design
with cycle priority at the crossings
which is seven times more dangerous
than the design which I recommend.
This type of roundabouts causes between
 52 and 73 extra injuries per year in the
Netherlands. Copy the safe design
which is illustrated elsewhere in
this blog post.

It has been known within the Netherlands for many years that roundabouts which have annular ring cycle-paths and on which cyclists have priority over each arm are less safe than those of the design which we have in Assen (nationally, SWOV originally estimated an extra "52-73 in-patients a year" due to the dangerous design, there are now three times as many of them so it believed that an additional 100 to 150 cyclists a year are now hospitalized because of the poor "priority" design). The decision to favour the cycle priority design was taken in an attempt to increase cycling convenience at the cost of safety.

The safety cost of choosing cycle priority will almost certainly be greater in other nations than it is here in the Netherlands. Dutch drivers are more familiar with bicycles than drivers of other nations and there is also a good chance here that bicycles will dominate any particular roundabout, making them difficult to ignore or overlook. Neither of these factors can be relied upon in other countries. For that reason I suggest that the safer design presented here should be the only roundabout design for cyclists adopted by other nations.

2018 update: The number of roundabouts in the Netherlands has doubled since the report was written. Because the dangerous priority design was widely adopted there are now 100-150 injuries requiring in-patient treatment at hospital and concerns about the rising number of casualties due to this dangerous design. Please read more about this in a new blog post about this subject. The priority design has proven not to be beneficial to cyclists in this country and it won't be beneficial in your country either.

How much safer is this roundabout design ?

Section from the English language summary of the report on
roundabout safety. The with-priority design is barely safer
than an un-signalled crossing while the safe design shown
recommended here is very much safer.

People keep asking me how much safer this roundabout design is than the "priority" design and if there are any figures to prove this. The document linked two paragraphs ago (there's an English language summary on page 5) gives the answer quite clearly. The annular ring design with cyclist priority is 11% safer for cyclists than an un-signalled junction while the same annular ring design without cyclist priority is 87% safer for cyclists. i.e. The expected injury rate due to cyclist priority alone, on the annular ring design, is nearly seven times higher with cyclist priority ( (1-0.11) / (1-0.87) ~= 6.85).

The roundabout design recommended here is, at the very least, seven times safer than the alternative Dutch design

However the design which I recommend is specifically designed in order to improve sight lines and also to lower both cyclist and driver speeds at the point of conflict (rather than slowing cyclists only at the point of joining the ring). We can therefore reasonably expect that this design will be associated with better injury rates. Combining both the improved sight lines and the better result for priority should result in a much better than 7x improvement in safety. The difference in outcomes suggests that estimating that the improved layout results in at least a 2 or 3 times safety improvement is quite conservative, leading to the safe design described above being at least 20 times safer than the unsafe design with cyclist priority.

There is no need to guess as we do have figures. We see a very obvious result in real life statistics for roundabouts. Injuries are rare at the design which I recommend, while they are remarkably common where the annular ring design is combined with priority for cyclists. Remember that these figures come from real injury statistics in the Netherlands, with Dutch drivers who are familiar with cyclists. There is likely to be a much greater difference in safety should the same designs be tried in other countries where drivers are less familiar with and less respectful of cyclists.

Note that the 11% improvement in safety for the priority roundabout design over an un-signalled junction for Dutch cyclists with Dutch drivers is a very small figure. You shouldn't necessarily expect this to apply for cyclists in other countries from the same design. It may even be that the situation is worse than an un-signalled junction in other countries. But the very strong result from the safe roundabout design is likely to still have some significance in other countries.

Safe vs. "convenient" ?
The comparison between these two roundabout designs has in some places taken the form of an argument about safety vs. convenience. There is an attempt to paint the added convenience of one type of roundabout as a certainty while the safety advantage of the other is played down as being "very slight". In fact, it is proven that the safer design (as recommended in this blog post) is seven times safer for cyclists than the other design, while the relative convenience of the designs is open to debate. I find that the safer design is also very convenient. If you doubt this, please watch the first 80 seconds of a video in which I demonstrate how I regularly cross the roundabout illustrated above in both directions without stopping.

While the design on the left is often referred to as a "cyclist priority" roundabout, cyclists actually have to give way on both types of roundabout. The main difference is that the point where you give way is not coincident with the point of conflict on the design on the left while it is coincident with the design on the right. This means that the cyclists at most have to slow down and speed back up once with the design on the right and can do so while assuring their own safety. Note that drivers have to give way at the same point on both roundabouts, and that giving way to cyclists in the Netherlands is significant because there are often more cyclists than drivers using junctions in this country. The case shown above is a best case so far as the "priority" roundabout is concerned. Sometimes they are very much less convenient as can be seen in a video.

A much smaller example following the
safe design princples. A busy
roundabout serving a high-rise car
park which does not injure cyclists.

The principles of design are important, not this exact size and design
I chose this particular example for the video because it's very clear what is going on. It's large and it's relatively green for an urban location, but this makes makes it easy to demonstrate in a video how the roundabout works. The principles which make it safe (90 degree crossings, good sight lines, plenty of time to make decisions, obvious priority, some journeys made without joining the roundabout at all) can be, and often are, applied on a smaller scale.

The small size of the island at this
roundabout can be seen in this photo
from a recent study tour.

The smaller example illustrated here applies all the same principles as the main example above but on a much smaller scale. It could in fact be made smaller yet. There have been no cyclists or pedestrians involved in a crash here. Only two minor fender-benders between motorists are recorded, neither causing an injury.

Summary of points which make the safe roundabout safe

1. 90 degree crossings between cyclists and drivers to improve sight-lines of both.
2. Not relying upon drivers to take decisions which maintain the safety of cyclists or give way on behalf of cyclists but giving that control to cyclists themselves.
3. Adverse camber for cars going around the roundabout to slow cars down.
4. Refuges between streams of motor traffic which are wide enough to accommodate a whole bicycle.
5. Bidirectional cycle-paths because they allow cyclists to cross fewer streams of traffic - crossings are where the dangerous interactions occur.
6. Right turns take place with no interaction at all between cyclists and motor vehicles.
7. The layout makes it very obvious to everyone what they should do.

Not every junction should be a roundabout
CROW suggest that roundabouts are appropriate only on junctions with up to 500-1500 motor vehicles per hour on the busiest arm of the roundabout. Note that that is a peak not an average. It doesn't imply safety with 12000-36000 motor vehicles per day, but that the peak hour should be 500-1500 max. Most roundabouts in the Netherlands have flows considerably lower than the maximum allowed. Where more vehicles must be catered for, they suggest not having cyclists going around roundabouts at all, but using other junction types such as traffic light junctions or cycle unfriendly multi-lane roundabouts which then require grade separation (see next section).

Too little space ? Too much traffic ?
Think about Simultaneous Green, the
other really good junction design.

If you are looking to copy these principles but there is not space for a safe roundabout in your location then perhaps a roundabout is not the correct solution for you. There are other possibilities. Simultaneous Green traffic lights can work even for very small junctions, but in the Netherlands note that many traffic light junctions in small streets have been removed altogether, along with the motor traffic which they used to serve. By doing this, a safe situation can be achieved almost anywhere.

For a complete picture of all the complex junctions in Assen, see previous blog posts about every roundabout in Assen and every traffic light junction in Assen.

CROW suggest that a peak (rush hour) hourly intensive above 1500 motor vehicles always requires a tunnel, a bridge or a traffic light junction to be built instead of a roundabout. These solutions are also preferred at lower traffic levels (1200-1750 or >1000) in different situations.

Don't forget about unravelling
Another factor which leads to the safety and convenience of Assen's roundabouts is that they are largely avoided by cyclists. Bicycle routes here are unravelled from driving routes. Many of the 21 roundabouts feature only infrequently on cyclists' journeys or do not feature at all.

CROW suggest that higher traffic levels should result in cyclists being grade separated. Here's an example of just that. This roundabout on the ring-road in Assen has a perfect safety record for cyclists and probably always will have. Why ? Because there's absolutely no need at all for any cyclist to ever interact with motor vehicles on this roundabout:

This roundabout is even safer for cyclists, but it cheats by not really being a roundabout for cyclists at all. Grade separation should be the norm where cycle routes cross busy ring-roads which pose a safety risk.

Other real-life Dutch roundabout designs
Below you'll find examples of other roundabout designs used elsewhere in the Netherlands. Most of these examples have a less convincing safety record than the examples illustrated above. They're shown along with their safety records in order to demonstrate what does not work well and should not be emulated elsewhere.

Shared Space "squareabouts"

Drachten is a smaller town than Assen a few kilometres to our west.

There has been considerable international attention drawn to a Shared Space "squareabout" in that town. Much has been written about this being a safe design. However, if we ignore the hype and look at the statistics then we find a very different story:

Laweiplein Shared Space "squareabout" in Dracthen. There have been ten crashes here, injuring three cyclists and one moped rider. This single Shared Space junction is more dangerous for cyclists than all of Assen's 21 roundabouts and all of Assen's Simultaneous Green traffic light junctions added together. 

Turbo Roundabouts

Turbo-roundabout under construction
by a motorway junction south of
Assen. Absolutely no bikes near here.

There has been an unfortunate mis-understanding in the UK over turbo-roundabouts with at least one council seriously trying to implement a turbo-roundabout for cyclists.

This is a huge mistake. Turbo roundabouts are designed to maximize flow of motor vehicles. They're a good design for motorway junctions and similar places where there are many motor vehicles and absolutely no cyclists or pedestrians.

Note that Turbo roundabouts are also recognized to be dangerous for motorcyclists. Motorcycling groups have complained in the Netherlands.

Groningen

Dangerous roundabout in Groningen.
See the first picture below.

Groningen, which won the Fietsstad competition in 2002, is famous for having the highest cycling modal share in the world. This is the result of policies starting in the 1970s and it is also contributed to by the extremely high student population.

Unfortunately, the city has not progressed so well since 2002 as it did in the years before it was awarded a prize. Local campaigners have been vocal about this. Groningen's infrastructure is variable in quality but problems caused by this are to some extent masked by the high level of student cycling.

One of the most dangerous roundabouts in Groningen has been featured in previous blog post. We've used it for some time on study tours as a contrast with good roundabout design. To demonstrate what not to do:

This busy Groningen roundabout is the scene of 36 incidents in five years resulting in injuries to two pedestrians, three cyclists and two moped riders. This is not good design.

All of the roundabouts within Groningen are of the annular ring design and all give priority to cyclists. Unfortunately, none of them have an especially good safety record:

A suburban roundabout, relatively low traffic but with 18 crashes including six cyclist injuries.

A few metres away, this roundabout in the same suburb is the scene of 13 crashes including two cyclist injuries

This roundabout has different geometry to the other three and better sight lines. In particular, there is a wide verge the length of a car between the roundabout and the cycle-lane. This gives a space in which drivers can stop between the road and the roundabout in a similar manner to how it is possible for them to do so in the example above from Assen. However this detail but that hasn't prevented there being 8 crashes here. One cyclist and one moped rider were injured. I write about an experience at this roundabout below.

Just outside Groningen to the South we find a roundabout more similar to the design used in Assen, with better sight lines and where motorists have priority. At this roundabout there has been just one collision between a motorbike and a bicycle which unfortunately caused an injury. The vertical grey line in the roundabout is a sculpture.

Zwolle
Zwolle is the current holder of the "Fietsstad" award, an occasional award presented to the Dutch city which is considered to be trying hardest to grow cycling.

Zwolle's "Bicycle Roundabout", built last year, has similar
appearance to known unsafe designs and as yet no safety
record. I'm not praising it unless it turns out to be safer than
it looks.Update: See below. Cyclists were injured here within
weeks of opening.

Zwolle achieved an amazing amount of positive press last year for an unusual "bicycle roundabout" (fietsrotonde) junction design. This unproven design was even used as part of the marketing campaign for the city's Fietsstad competition entry. The "bicycle roundabout" works as a roundabout for cyclists while for drivers it is a straight through road. The kerbs are narrow, sight lines are short and crossings are not at 90 degrees. Press releases about this junction and other sources have made claims made about its safety but in my view praise should wait until there is a proven record of safety. That is why I did not write about this junction before now. We must first wait to find out what the long term safety outcome is and until then treat the new design with caution. This is especially not something for other nations to try to emulate.

It is claimed that Zwolle drivers' familiarity with existing roundabouts will lead to the bicycle roundabout being safe. I see this as spurious as while Zwolle doesn't have many other roundabouts those that it does have actually do not have a good safety record at all by Dutch standards. There are some examples below.

Update: I've discovered that the Bicycle Roundabout in Zwolle has in fact already claimed victims. It opened at the end of August 2013, the first cyclist injury was in September and another cyclist was injured in November. Zwolle's Bicycle Roundabout has therefore claimed as many victims in three months as all twenty-one of Assen's roundabouts caused in five years. Even relative to the previous supposedly unsafe situation this doesn't seem very impressive. According to the Ongelluken Kaart, there was only one injury in this location in the five years between 2007 and 2012. Also read how the Bicycle Roundabout was advertised in advance as part of the effort to win the cycling city (fietsstad) award.

Further update: Thinking more about this, it seems that the whole idea of the "bicycle roundabout" is flawed. Compared with the unsignalled junction which existed before it was built, a normal roundabout of the type used in Zwolle might be expected to achieve a 75% reduction in injuries to motor vehicle occupants but just an 11% reduction in injuries to cyclists. However, the bicycle roundabout as built doesn't meet good guidelines even for that type of roundabout. Sight lines are very short. What's more, given that part of the reason for enhanced safety for cyclists at a normal roundabout is a result of drivers being able to make a choice not to exit the roundabout at a point where there is conflict with cyclists, and given that in this instance that choice has been removed and drivers are forced to exit in conflict with cyclists, there seems no good reason at all for anyone ever to have assumed that this design would in fact be safer. Therefore the elevated injury rate due to the bicycle roundabout should be no surprise to anyone.

Update 2018: In a reader's poll in a local newspaper, the Fietsrotonde was chosen by cyclists of Zwolle as what they believed to be the most dangerous place in the city for cycling. Perhaps more worryingly, even though it had been improved since I wrote this piece, the first roundabout featured below is still of the priority design the the council now admits that this is the most dangerous place in the city for cyclists. If Zwolle had instead converted the roundabout into the the safe design which I recommend then this would not have happened.

Zwolle Urban roundabout with priority for bikes. 15 crashes here including four cyclist injuries
Update 2018: Zwolle completely rebuilt this roundabout, but instead of choosing the safe design featured at the top of this blog post they changed to a different unsafe design so this continues as the most dangerous location in Zwolle for cyclists.

Zwolle Suburban roundabout with priority for bikes. 25 crashes here including six cyclist injuries.

Another of Zwolle's cyclist priority roundabouts. 22 crashes here including two cyclist injuries

Eindhoven
Eindhoven is a city which we used to visit quite often as for a while we thought we might settle in that area. It's a larger city with few roundabouts. Much as we've seen elsewhere, the roundabouts which have priority for cycles have injured cyclists while those which keep cyclists well away from motor traffic have not:

Eindhoven roundabout with priority for cyclists. Ten crashes in total, four cyclist injuries

This junction resembles the design used in Assen, but it is truly enormous in scale. It gives cyclists priority. The crossings are far from corners in the cycle-paths and far from the roundabout, which itself has a much larger radius and will support higher speeds. Perhaps it is the resultant speeds of both cyclists and motorists alike at the crossings which adds danger here. Two cyclists have been injured here in five years.

On the other hand, this enormous multi-laned roundabout in Eindhoven has caused no cyclist injuries at all. Why ? Cyclists are completely grade separated from motorists. Therefore, despite the huge size of this road junction, it is both safe and convenient for cyclists to use.

This is the Floraplein in Eindhoven. A turbo-roundabout. Turbo-roundabouts are designed for maximum flow of motor vehicles and should never be built where there are cyclists, but this one was. There has been much local opposition to this roundabout including a protest video showing the problems that it causes. I featured a video of this roundabout in a blog post from 2012 in which I warned against campaigners mistakenly calling for this infrastructure for cyclists. Needless to say, between 2007 and 2012 there were multiple collisions here, several involving cyclists and one cyclist had to go hospital as a result.

Valkenswaard

Valkenswaard roundabout visited in 2006. Not a safe design.
See below for statistics.

Valkenswaard is a village outside Eindhoven which we visited on the 2006 study tour. At that time I was myself impressed by the idea of cyclists having priority on roundabouts. Of course everyone is attracted to the idea of priority, but when we find out that the statistics show this design to unsafe, resulting in people having been sent to hospital because of injuries which occurred here we should of course think twice about the value of such a design.

In 2006 our group spent some time looking at and riding around this one roundabout in particular as cyclists had priority there. That's why I've included this village in these examples.

We now know that this wasn't really a good example to take notice of as even though this is just a small village and there is little traffic here, this roundabout is the site of quite a number of cyclist injuries. Compare this photo with the new Zwolle bicycle roundabout (above). The obvious similarity is part of why I am skeptical of that new design.

A roundabout which the 2006 study tour group were somewhat enamoured by. It's in a relatively low traffic situation suburban but there have been seven incidents here including three cyclist injuries. i.e. even this single roundabout in a small village is more dangerous for cyclists than all of Assen's 21 roundabouts put together. This is because the annular ring design is more dangerous for cyclists even when traffic volumes and speeds are low.

Outside Valkenswaard, a rural roundabout without priority for bikes. Just one crash, no injuries, no involvement of cyclists.

Outside Valkenswaard, a busier roundabout without priority for bikes. No cyclists involved in crashes here.

Enschede
One of the most influential pieces of research in the Netherlands which convinced many people that cyclists having priority on roundabouts was a good idea was carried out in Enschede in 1991 and appeared in a report from 1992. Unfortunately, as is admitted in the conclusion of that report, their positive result was based upon research which involved just a few hours of observation. Based on their short observations, they estimated that the change in priority would have a very small effect on safety. We've now had many years to see what really happened (these roundabouts have proven themselves to be seven times more dangerous as detailed above). This is the very same roundabout as was used for the 1992 research:

The roundabout between the Knalhutteweg and Broekheunering in Enschede used for the investigation into cyclist safety with priority on roundabouts. There were 23 collisions in five years here, two of which injured cyclists, while two more injured a moped rider and a pedestrian. For cyclists, this roundabout, used so often to "prove" the safety for cyclist priority, as shown itself to be as dangerous as all 21 roundabouts in Assen combined.

A few hundred metres to the North, this is the roundabout between the Knalhutteweg and Vlierstraat. At this location, there have been 15 crashes and no fewer than five cyclists injured in five years.

Closer to the centre of the city, this roundabout has been the site of 38 crashes. In this case only one cyclist was injured, but two car occupants were also injured in one crash.

Another Enschede roundabout. This example has had 20 crashes over 5 years. Six cyclists were injured here.

Looking for relatively good examples from Enschede, I found this "roundabout", the location of just five minor crashes and no injuries over five years. Suspicious of the exposed ground on the left of the picture, I looked at Streetview which revealed that this wasn't a roundabout at all during the time when the statistics were counted. It will be interesting to see what happens here in the future. Will converting this previously very safe junction into a roundabout lead to a safety improvement ?

Fietsberaad still have the Enschede roundabout as a good example on their website. I disagree. The four roundabouts in Enschede that I feature above have wounded 14 cyclists in five years. That's seven times so many injuries as all 21 roundabouts in Assen combined. This gives each of the Enschede roundabouts which I looked at a safety record on average 36 times worse than an average roundabout in Assen.

Purmerend
A webcam set up to observe a roundabout in Purmerend has unfortunately led to people from the English speaking world thinking that they're observing a safe example from which to copy. In fact, the Purmerend roundabout has caused many injuries to cyclists:

The roundabout in Purmerend near the software company "Archie CRM" has caused many crashes. It is recorded that twelve crashes occurred and that those crashes injured six cyclists such that they required hospitalization in just the two years of 2008 and 2009. There's a lack of data for other years but the design of this junction has not changed.

's-Hertogenbosch
Den Bosch is another of the cities where the more dangerous design is preferred and another where the most dangerous junctions for cyclists are roundabouts.

The most dangerous junction for cyclists in 's-Hertongenbosch is this roundabout which caused hospitalization injuries to five cyclists and three moped riders in the three years between 2008 and 2010. These are not good examples of roundabouts to copy from.

Update: Where the danger comes from
It seems I need to explain more about why the roundabouts with priority dangerous, regardless of their layout. It's not just that the annular design of cycle-paths makes visible difficult but also that it expects perfect behaviour from drivers.

Giving cyclists "priority" sounds positive, but what actually happens with the priority design of roundabout design is that cyclists are stripped of control. The design requires that cyclists should ride out in front of motor vehicles and hope for the best. On this type of junction design, cyclists are used as mobile traffic calming devices. The cyclist priority design requires that drivers who don't know the rules, are tired, talking on the telephone, changing channel on their radios, arguing with other people in their cars, who can't see out of misted windows, who are impatient and don't want to stop for a cyclist (especially important in other nations where there is more anti-cycling sentiment than here) or who are simply not skilled at driving must never make a mistake because the safety of cyclists depends almost entirely on the driver and not on the cyclist themselves.

My view is that cyclists make better decisions about their own safety than drivers can make for them. This is supported by the comparative injury statistics above for roundabouts which give cyclists control over their own safety vs. those which give them "priority" or supposedly let them share equally with drivers.

An incident from earlier this week may help to explain. Judy and I rode nearly 80 km planning a cycling holiday route and we passed seven roundabouts on our way. Five of them were of the safe design and were crossed without stopping. One was of the safe design and we had to wait about ten seconds.

I'm the red arrow, the learner is the blue
arrow, the woman from the right is the
green arrow. There's too much to look
out for here. That's the problem with
this design. Good design doesn't rely
upon bright yellow warning signs to
try to enforce priority.

Just one of the roundabouts on our route was of the "priority" design. This just happened to be the same roundabout as I had already written about above as one of the safest in Groningen (it has better sight-lines than many and there have been 'only' eight crashes). On this roundabout, we needed to go straight on (second exit) so joined the annular cycle-path. At the same time as I joined the cycle-path around the roundabout, a learner driver who had been travelling parallel with me with his right indicator flashing joined the roundabout. I had to trust that the learner had seen me, that he understood the priority rules and that he was going to stop. He did, but he did so a little late and his front bumper was uncomfortably near the cycle-lane. My attention was distracted by the learner approaching from my left and I wasn't looking out for the driver coming from my right who had also not been paying attention and who stopped her car very sharply half way across the cycle lane in front of me. I had to swerve to avoid her car.

There was no crash and both these drivers stopped, but they both did so too late. With slightly different timing, for instance if either the drivers or myself had been going slightly faster or slightly slower, it could have worked out differently. This is not fail safe design. SWOV point out that "drivers have to make (too) many observations in a brief time span, resulting in them noticing cyclists too late" and that is precisely what seems to happen at cyclist priority roundabouts.

That is but one anecdotal illustration of the type of incident which simply doesn't happen with the roundabout design which I prefer, and which has been proven to be safer. We have known for more than a hundred years that we cannot rely upon perfect behaviour from drivers but this is what the priority roundabout design does rely upon. Instead of cyclists being able to take safety into their own hands, their control is taken away and their safety is assured only by drivers behaving perfectly. The roundabout priority design flies in the face of the sustainable safety principles which otherwise keep Dutch roads safe.

Even very young cyclists can ride
safely across this junction in Assen
where cyclists have priority over
drtivers. Perfect safety record here.

This blog post is about roundabouts
Don't confuse the concerns about safety at roundabouts with priority with other locations and situations. It is never helpful to try to apply a one size solution to all problems.

Concerns about roundabout priority do not apply in other situations. There are many thousands of safely designed junctions between roads and cycle-paths, here in Assen and elsewhere in the Netherlands, where cyclists have priority. Where this is the right solution. i.e. junction design is good, sight lines are long and traffic volumes and speed are not overly high, these junctions have very good, often perfect, safety records.

It is the existence of such infrastructure which makes cycling both convenient and safe in the Netherlands.

Find out more
Book a study tour to find out more about good junction design and other factors which lead to the high rate of cycling and good safety record for cyclists in the Netherlands.

¹ The CROW Design Manual for Bicycle Traffic states that "On roundabouts inside built-up areas, it is recommended that cyclists on separate paths continue to have right of way. After all, this corresponds with a cyclist-friendly policy". I disagree that this is the best way to design roundabouts, especially when considering road conditions and existing road use conventions in other nations. The CROW manual also refers to low traffic (less than 6000 pcu/day) roundabouts as not requiring cycling infrastructure. In reality, roundabouts in the Netherlands without cycling infrastructure are roughly as common as unicorns. I can't remember seeing a single example.

The Dutch Institute for Road Safety Research, SWOV, are also skeptical about roundabouts which give priority to cyclists. You can read more from them here: http://www.swov.nl/rapport/Factsheets/UK/FS_Roundabouts.pdf, http://www.swov.nl/rapport/R-2004-14.pdf


Part way through writing this blog post, several people drew my attention to the new Austroads document about cycle-lanes around roundabouts. They came to a correct conclusion that encouraging people to cycle around the edge of roundabouts is a bad idea, but their suggested fix (sharrows to encourage cyclists to "take the lane") is not adequate. The design presented above works well for all abilities of cyclist.

All the aerial photographs with flags showing collisions on this page come from the excellent ongelukken kaart. This shows all crashes in the Netherlands between 2007 and 2012. Blue flags indicates crashes and the number is how crashes have occured at that location. Yellow flagss indicate that at least one injury occured, red indicates at least one death

This post originally referred to 19 roundabouts in Assen which I had written about in a previous blog post. That has now been updated to cover an additional two roundabouts which I overlooked. These had also not injured cyclists.

Update 2018: A study tour participant made this drone video of the roundabout at the top of the article: