Monday 19 September 2011

Every Roundabout in Assen. Variations of the safest roundabout design.

Every roundabout in Assen has cycle facilities which mean that cyclists don't use the road on any of them. Their designs vary quite widely depending on context but they have common features which make them safe and they all examples of good practice. In this blog post I show what all of these roundabouts look like. The roundabouts of Assen have a particularly good safety record: there were just two cyclist injuries over five years at all twenty-one of these roundabouts combined. This is why Assen's roundabouts make a good example for other nations and even for other cities within the Netherlands.

Here are aerial shots of all the roundabouts in Assen. The images are taken from Google Maps. If you're interested, you can look for them, with their context, yourself.
Roundabout on ring road. The underpass from South West to North East, nearly as wide as a road, provides direct cycle access to the city centre without having to stop (previously seen here). The cycle path is four metres wide, and next to it (barely visible in the picture) is a two metre pedestrian path. The North-South road is the ring road around Assen. Cyclists are not permitted to use any of the roads in the picture, so not having access to them is not a problem. Going through the underpass is in any case quicker than going around the roundabout. See what the experience is like for cyclists at this roundabout in this video. No crashes of any kind in five years, no injuries.
North of the city, this roundabout connects the motorway junction with the direct road North. High quality cycle paths go in all directions except onto the motorway. The paths heading North are unbroken for 5.5 km to and through the next village. They have an especially smooth concrete surface which has priority over all side roads and are well separated from the road to and through the next village. At this point there is no pedestrian path as there is little pedestrian traffic. The few people who make this longer walk use the cycle-path. Over five years, there was one incident here where a driver left the road and hit a piece of street furniture. No injuries.

In a new and as yet undeveloped industrial area, the cycle (red) and pedestrian (grey) paths don't provide access to the road to the North East - towards the motorway junction. Zero incidents.

Near "big box stores", a combination of cycle paths, and service roads provide easy access by bike, while pedestrian paths provide routes for pedestrians. Cyclists are required to cross two lanes at once in the bottom left corner of this roundabout and this makes it one of the less easy roundabouts to use by bike. There have been a number of motor vehicle collisions here, two cyclists involved in crashes, one of them injured.

Near an industrial area at a ring road crossing. Cycle paths provide for all directions except along the ring road which is closed to cars (there are other routes for bikes). One incident here in five years - a driver left the road and collided with street furniture. No injuries.

The ring road is intersected by direct cycle route to the centre of the city from outlying villages. No recorded incidents here in five years.

Busy road to the East within a residential area. Cycle paths go in all directions around this roundabout, merging with 30 km/h roads to the North and South. Four crashes here in five years, one motorist injured. No cyclists involved in any crash.

Industrial area. Cycle path approaches from the North, access road continues safe access to the South. To the East is a motorway junction. No cycle access there. No incidents here of any type.

A junction on the ring road by which cars bypass the older direct route to Assen. No need for bikes to use the road West to East here as this is merely a bypass of the older and more direct route a little further North which remains open to bikes but is no longer usable by car. This roundabout has an extra lane which allows drivers to go from west to east without giving them the option to turn left. This combined with the requirement that cyclists cross two lanes at once makes it more difficult for cyclists to use safely. Happily it is not quite so bad as a turbo roundabout, and it is in any case not a heavily used junction by bike. Three crashes here in five years, none involving injury to drivers, none involving a cyclist.

Junction inside residential area. Note that large "30 km/h" signs on the residential streets s are visible, as are cycle paths in all directions. 30 km/h roads sometimes have separate cycle paths. No incidents here in five years.

On the western edge of Assen, motorists are now directed to the south instead of continuing along the canal. The old direct route into the city alongside the canal remains a through road by bike but not by car. Two crashes here in five years, no injuries to drivers, no cyclists involved.

In a new housing development, cyclists mostly travel South to North-West or North-East. An extra access is provided for people who live on the West. One crash between cars here in five years. No injuries. No cyclists involved.

An asymmetrical arrangement. The main route is North to East, so the cycle paths are not the same on the west wide. One crash between cars here in five years. No injuries. No cyclists involved.

In a new residential area, the road to the south west has a 30 km/h speed limit and is relatively lightly used. No crashes here in five years.

Residential area, cyclists can more easily access homes than motorists can. No crashes here in five years.

A direct route to the new suburb on the west of Assen is provided here. The road to the North East is access to a natural gas extraction facility and does not need cycle access. No crashes here in five years.

This area to the West is as yet mostly undeveloped. However, the roundabout has been built in preparation for cycle traffic which may appear in the future. No crashes here in five years.

Where the ring road passes close to a residential area and a route out of the city to the North West, a cycle path provides for the only direction that cyclists need to go in this location. Seven crashes here in five years, and one cyclist injured. Compare with the first example where grade separation prevented any cyclists being injured on a crossing of the ring-road.

Between residential areas on the West and the centre of the city, this roundabout is one of the busiest in Assen for cyclists, provides good access by bicycle and has proven to be very safe. Four "fender benders" here where motorists have shunted each other. No injuries, no cyclists involved. Another blog post expands on this this very safe roundabout design detailing all the design features which make it work so well. 
Update 2014: I forgot to include this one. It has the same priority rules as the others, but is built on a much smaller scale. No cyclists injured here in five years, but there have been two "fender benders" (motorists running into each other, no injuries)
Update 2014: I forgot this one too. Near a large bus-stop with much cycle-parking, it serves many buses as well as many bikes. It's on the main route North from Assen, but as the majority of the traffic travels in a tunnel this doesn't affect the roundabout. This is the site of three collisions in five years, none causing injury and none involving a cyclist.

Finally, just because someone will probably spot it on a map, there's also this "roundabout" with no obvious cycle facilities. However, actually it's not really a roundabout in the same sense. This is a residential area without through routes for motor vehicles:
This is a small "roundabout" in a residential area. All streets have a 30 km/h speed limit, and are arranged so as not to be through roads for drivers. However, it's not equivalent to the others. These roads are not for through-traffic. This is an example of segregation of modes without cyclepaths. The same rules do not apply. Take a look on streetview. This roundabout had no incidents of any kind in five years.
On this side of the North Sea, cycling facilities are not an optional extra to be omitted at any time that it's a little difficult to work out what to do, but a fundamental part of the design of roundabouts - just as with everything else on the roads.

To design a Dutch inspired roundabout adopting only the geometry but without cycle paths, as I've seen proposed in the UK, is to very fundamentally miss the point. This is just one of many ways in which what has been achieved in the Netherlands has been misinterpreted elsewhere.

For cycling provision to be able to influence peoples journey choices and encourage a high modal share for cycling, it must be universal and consistent. This way you get adequate subjective safety so that people will cycle. It is never too late to start building such a network, and it won't take as long you think.

Think these designs won't fit your town ?
Roundabouts are only safe for cyclists with relatively low traffic flows and relatively good sight lines.

If you have roundabouts in locations where these roundabout designs wouldn't fit, it's quite likely that those junctions wouldn't be roundabouts at all in the Netherlands. Please read a companion blog post which shows every traffic light junction in Assen, many of which are of the the simultaneous green design - the safest traffic light design for cyclists. This may be a more appropriate design for your location, as could be an attempt to unravel routes.

Safety ?
In Assen, cyclists do not have priority where cycle-paths cross roads approaching roundabouts. This has been shown to be safer than the design used in some other parts of the Netherlands where cycle-paths have priority over the road crossing. Whether or not to give cyclists priority has long been a contentious subject because of this balance between safety and convenience. There is a big contrast between the safest designs and the least safe.

2014 update
Since this blog post was written, Assen has built one new roundabout in a residential area which is very similar to the tenth example above complete with similar cycling infrastructure and begun construction of a turbo-roundabout. Turbo roundabouts are a special kind of roundabout designed to deal with high volume of motor vehicles. They are not intended to be used by cyclists. Assen's new turbo roundabout is being built to cater for a new motorway junction well away from any cycle routes. It is not easy even to approach by bike.

2015 update
One roundabout in the city has been removed and two more constructed. One of the two new roundabouts is of a poor design, with no proper place for cyclists to wait between the two streams of traffic:

Crossing the arm of the roundabout shown at the top in the map segment above. Note that a few rough bricks which give the appearance of a central reservation just half a metre wide are absolutely no barrier to the tyres of a truck.
This arrangement does not seem safe, particularly at a busy location for both cycles and trucks. This location is a junction between a main cycle route west-east and the entrance to an industrial area north. In the past, there was a cycle-priority junction here which had effective devices to prevent motor vehicles from cutting the corner and it had a perfect safety record so far as cyclists were concerned. This roundabout is too new to yet have any statistics associated with it.

Outside the city, another turbo roundabout has been constructed south of Assen, again this is not intended for the use of cyclists, and other roundabouts of the safe design for use of cyclists have also been constructed near the TT track.

Update 2018 - a new roundabout
While other works have been ongoing, a temporary roundabout was constructed in Assen with cycle priority. i.e. the dangerous design. Unsurprisingly, there were injuries at the temporary roundabout. The new design which will permanently take its place has now been made public and this is a return to a variant of the safe roundabout designs which Assen has elsewhere in the city. No two locations are identical and therefore no two roundabouts are identical either (all the designs above differ). This new roundabout will be unlike all the others, and it does involve a bit of a compromise due to having to fit into a 1960s road design including a tunnel which will not be rebuilt. However this design keeps all the important features which ensure safety:

Roldestraat runs left to right across the image. On the right is the entrance to a tunnel which dates from the 1960s. On both sides of the road there are 2.5 m wide bidirectional cycle-paths. These are the narrowest bidirectional cycle-paths in the city, their width being a consequence of their age and the huge expense of rebuilding a tunnel. All other cycle-paths are either 2.5 m wide for single direction cycling or 3.5 m or more for bidirectional cycling.
Cycle-paths for single direction travel in red, bidirectional in green and bidirectional crossings in blue. Note that this design never requires any cyclist to cross the road more than once. The most awkward part of the design is a consequence of the layout of these roads: Cyclists coming into the city (right to left) who have passed through the tunnel will have to make a sharp right turn before turning left to cross the road to continue into the city centre. This is slightly awkward but should be safe. Cyclists heading out of the city left to right will be able to cycle straight through without stopping at all. Note that cyclists do have priority over the road to the south, but this will not be busy: It is to become an exit only for cars from a few residential streets.

Overall I think this is a very good redesign of this junction. It's slightly inconvenient for cyclists heading from east to west, but safer than the existing situation. For cyclists heading west to east it's both more convenient and safer. Use of bidirectional cycle-paths helps to reduce the frequency with which cyclists have to cross the road, which is when they are exposed to danger. Overall this is a plus for Assen cyclists.


Martin said...

Now that's a lot of roundabouts, people in Aus. always complain about Canberra being the roundabout city. Yet compared to the Netherlands it would be the norm in road planning.

Slow Factory said...

Looks superb for suburbs and rural areas. Can you do a focus on Dutch urban crossroads, also from the top?

Frits B said...

Isn't the car park on the right of the second photo part of a bus station, or at least a place where all buses pass and allow for changes?

The small "roundabout" on the last photo is the only way to connect five streets in an orderly manner. It's a lot smaller than it looks on Streetview, and has so little traffic that people often cut corners (I know, I live in the cul-de-sac in the top right corner). The birds are ravens; the original greenery were shrubs and trees which blocked the view so were removed.

Reaperexpress said...

What about pedestrians? I notice that some of the roundabouts only have cycle paths, no sidewalks. Do pedestrians walk on the cycle path?

It's the opposite here in the Greater Toronto Area. Sidewalks are everywhere, but cycle paths are rare.

David Hembrow said...

Reaperexpress: Good point. I've updated some of the descriptions. In general, anywhere where you might find an appreciable number of pedestrians you'll also find separate pedestrian paths. The cycle-paths in the town usually have pedestrian paths next to them. However, where there are rarely pedestrians, such as outside the city boundary, there are no specific paths for pedestrians and the few people who walk here use the cycle-path. They're rare enough that this doesn't cause a problem for either group.

Shared use paths intended for use of large numbers of both pedestrians and cyclists are not built in the Netherlands.

David Hembrow said...

Frits: Yes, the second photo is that roundabout, at the very top of the city. I really ought to write something about the Dutch concept of a "transferium", where people can swap modes between bike / car / bus.

Zmapper said...

We call them park 'n' rides.

Here is a typical "bicycle friendly" roundabout in the United States. Notice how the bike lane transitions onto a widened sidewalk.

Notice the High School on the 1/2 * 1/2 mile property to the Northeast. What a lot of excess land devoted to grass, which in near-desert Colorado isn't the wisest of ideas.

Clark in Vancouver said...

I love that to bike past a highway you go under it instead of waiting for a gap in motor traffic to cross it.
These types of things could also be applied to other highway interchanges other than roundabouts. Even just where a highway is raised they could just make it a little higher to put a tunnel underneath. The nice wide, open ended tunnels you've shown before are great to avoid any worry of social safety.
In Richmond, BC, Canada there's a main highway that crosses through it with really no way to get across it by bike except to go way out of your way to underpasses.
Something like this would work well at the interchanges. All they would need to do is make the ramps start earlier and put a tunnel underneath.

Anonymous said...

Anyone else notice that roundabout #9 looks like a smiley face? Brightened my day no end.

Kevin said...

There is a new one added lately:

And yep there are alot roundabouts here :) though it does work really well!

At the moment they are still creating another one, which isn't on google maps yet.

if you want more information about one of the roundabouts here in the netherlands feel free to ask :)

Contact me at:

Peter Furth said...

Great inventory! You're right to distinguish that last "roundabout" from the others; in the US, we call it a "neighborhood traffic circle" to distinguish it from a circular intersection that carries through traffic.

My students recently did a study of bicycling facilities at roundabouts in the Netherlands, focusing on the Delft / The Hague region. They managed to find one older roundabout without bicycling provisions -- a solution permitted in the CROW Dutch design manual, but not used very often. All the rest had cycle tracks or bike bypass tunnels. We also found a rare case of bike lanes in a roundabout, a practice not recommended by the latest CROW manual, but allowed to remain because it hasn't shown any safety problem.

Another student group did a study of the roundabouts in Pijnacker, a suburban community near the Hague, Rotterdam, and Delft. While the study's focus is more on traffic safety, the Pijnacker roundabouts all have bicycle facilities.

Thedoc said...

Good examples but are there any examples of very busy roundabouts with built up areas around them? I am talking like two lane 40mph approaches and at least 1500 vehicles going in opposing and heavy left turn traffic from the more minor arms?

Would be interested to see if there is something like this in Holland and how it deals with the cyclists getting across. Obviously with roundabouts of this nature being congested the cyclists are going to struggle to find gaps to cross with a motor priority. Also Zebra's would be out due to approach speeds.

We have a lot of roundabouts like this surrounded by houses and we always find it very difficult to find a way across apart from making people stop at toucan crossings.

David Hembrow said...

Thedoc: There are no examples at all of the type of roundabout that you ask about anywhere in the Netherlands. These are simply not built.

Roundabouts are considered to be suitable up to a relatively small number of vehicles per day, above which the Dutch build traffic light junctions.

One modern exception is the turbo roundabout, a type of multi-lane roundabout which is intended for more heavy usage by motor vehicles. But note that this type of junction is normally constructed in such sites as motorway junctions. Cyclists should never go anywhere near large junctions like this and certainly not have to cross the road on the level.

The correct approach to large roundabouts with high traffic volumes, which cyclists will struggle to cross and where zebras are impossible is to either remove the motor vehicles to create an environment in which a roundabout as above is possible or to give cyclists a grade separated crossing such as the one shown in this video.

But ask yourself this: Why on earth has the UK built so many huge junctions in the middle of housing areas ? It's a failure of larger scale planning and something that you will very rarely find in the Netherlands. Routes for cycling and driving are unravelled, taking motor vehicles well away from where people live. This not only improves conditions for cyclists but also for residents who don't have to live with noise and traffic fumes.

Multiparty Democracy Today said...

How many cyclists and or pedestrians is too many for a shared use pathway? (Assuming you don't build them like most of the rest of the world as a sidewalk you can ride on and instead build them as bicycle paths you can walk on).

David Hembrow said...

Restlesstablet: Almost none is "too many". That's why you always find a separate path for pedestrians anywhere that appreciable pedestrian flows are expected. More here.