|A promising design, but with unproven safety record so don't copy this yet.|
|A particularly poor "with priority"|
design. No sight-lines, no reaction time
Frequent injuries at this location.
- It slows both cyclists (by tight corner radii) and drivers (by use of narrow lanes with raised tables), giving both more time to react at the crossing.
- Good sight lines are ensured because cyclists and drivers cross at right angles to one another.
- While turbo-roundabouts require multiple lanes, this design keeps the cycle crossings far enough from the roundabout that cyclists are required to cross only one lane of motor vehicles at a time.
- A generously sized safe refuge is provided between the two streams of traffic.
- The crossings being placed at a considerable distance from the roundabout itself means that the moment in time when drivers negotiate with cyclists on the crossing is distinctly different from that when they have to negotiate with other drivers on the roundabout.
Why it may not be so safe as is hoped
I think there is great promise in this design but I must sound a note of caution.
|Raised tables slow motor vehicles where|
cyclists have priority at the crossings, but
they resemble less successful crossings.
- The distance between the crossings and the roundabout is quite large, but for drivers entering the roundabout the distance between the crossing and the point where they need to choose a lane is very short. This may distract drivers such that they are less likely to notice cyclists.
- Raised tables on straight roads have only a slight effect of slowing drivers. When I looked at three different priority crossings a few days ago, the crossings where drivers were effectively slowed had more measures than just a raised table and the example which barely slowed drivers at all looked very much like these crossings.
- This isn't the first time that priority has been combined with a layout which provides better sight-lines. For example, one attempt to design a roundabout in Eindhoven combining good sight-lines with cyclist priority resulted in some injuries.
Experiments are not always successful
Without experimentation we can never discover new and perhaps better ways of doing things. The Netherlands leads the world in cycling infrastructure design, and experimentation continues here. This is a good thing. But ideas should only be adopted more widely if they have been proven to work safely and efficiently.
Experiments which didn't work out so well include an experimental cycle-path surface which was installed near Assen in 2009, but then replaced again in 2013 after it had proven not to provide an adequately comfortable surface for cycling.
There was also the Zwolle "fietsrotonde" for which bold claims were made in advance, but where poor design caused injuries within months of opening.
As of right now, there is precisely one roundabout of this new design in the world. It should be viewed as a brave and worthwhile experiment and it may eventually form the basis for yet safer conditions for cyclists in the Netherlands, but it should not yet form the basis for other experimentation elsewhere. We do not yet have long term accident statistics for this design and it is premature to make any claim about whether or not this new design is in fact safe.
Note also that the new design requires a very large footprint in order to provide the required sight-lines and space for the lanes of the turbo roundabout. As such, it's unlikely to be able to be applied everywhere.
What to adopt in other countries
For experimentation elsewhere it makes most sense to copy the proven safest Dutch designs. So far as roundabouts are concerned, this is it:
|This design provides the best basis for emulation elsewhere. Such roundabouts have the the best safety record within the Netherlands and are likely to remain safe even if aspects of the design are compromised.|
|Awful roundabout design from London|
widely described as "Dutch", but
actually nothing of the sort. This is
one of many awful recent proposals
from London, none of which are
similar to Dutch designs which they
claim to have copied.
In order to try to assist planners and campaigners alike to make the right choices, we offer cycling study tours which take a unique, independent, view of Dutch cycling infrastructure and which explain everything in plain (native) English. Book a place to discover more about what works well and should inspire new infrastructure design elsewhere as well as what works less well and should not be copied.
|Find out how how things really work in the Netherlands before trying to copy anything.|