A view from the cycle path: The danger of parallel kerbs and the advantage of angled forgiving kerbs

Monday, 15 December 2008

The danger of parallel kerbs and the advantage of angled forgiving kerbs

Parallel kerbs (parallel curbs in the USA) can be quite dangerous for cyclists. A slight lapse of concentration and you can be off your bike, and possibly injured badly enough to end up in hospital.

Like so many things, this doesn't have to be the case.

The kerb shown here is one of many "forgiving" angled kerbs in use in Assen. These kerbs make it possible to cross from the cycle path to the pedestrian path without falling from your bike. They reduce the risk of injury due to a lapse of concentration.

Note that the rise is very small. Only a few cm. When taller angled kerbs are constructed, these do not enable safely mounting the pavement. Also note that the angle is important. If the kerbs are much steeper than 30 degrees then it becomes difficult to ride up the kerb without the tyres sliding sideways. This of course becomes a greater problem when there is rain or ice.

The video demonstrates how you can ride up and down the kerb without losing control of your bike.

Explanatory captions are visible only when this video is played on a computer and not on a mobile device.

This kind of innovation makes the cycling environment very forgiving of errors, and keeps down the injury rate of cycling. It is one of the many very small details of the Dutch cycling environment which add up to it being very safe overall - the concept of making the road environment more forgiving of error is called sustainable safety.

These kerbs make it possible to take a bicycle onto the pavement when there is a lack of space, such as here during a cycle racing event (the road is being used for the race, the cyclists on the cycle-path are going slowly). Note that on the road side of the cycle-path there is no forgiving kerb. It would not help cyclists on this side.

In the city centre, cyclists can easily access cycle-parking facilities because of the kerb design.

Finally, an example which doesn't work. This is too high and a little too steep. It's not possible to ride up this kerb. It's a good example of drain treatment, though.

A reminder in 2016
Since this article was written, many other places have attempted to adopt forgiving kerbs. However, implementations elsewhere have often been of the "lost in translation" variety, with such mistakes as the sloped kerb being used to facilitate drivers using the cycle-path rather than to allow cyclists to use the pedestrian path. This photo hopefully will serve to remind people of how forgiving kerbs should be implemented:

This is the same cycle-path as shown towards the end of the 2008 video.

Built infrastructure such as the kerb treatment shown here and the extensive cycle-path network of the Netherlands are what give Dutch cyclists genuine safety. People choose to ride practical bicycles which include luggage racks, permanently mounted locks and permanently mounted dynamo lighting and other features which make cycling convenient, accessible and safe for everyone.

"Parallel" refers to the kerbs being parallel with the direction of travel. Even a very small gap can cause cyclists problems if it is parallel.

2 comments:

Anonymous said...: Yep - they van be pretty lethal. A raised lip of any more than a few mm is enough to trip you up if you approach at an oblique angle.

It happened to me a couple of years ago when out with my friend, The Irishman. I got away with just a sprained wrist, but he laughed like a drain. Which is why I was so glad to catch him on film making the same mistake earlier this year.

Kinda funny, but there's a serious point to it!; 15 December 2008 at 13:16
Multiparty Democracy Today said...: Will this kind of curb give you a bump if you ride over it to let you know that "Hey, you aren't supposed to be going there, it's the pedestrian area!" ].; 19 September 2015 at 08:00

Posts sorted by subject

The positive stuff
Three types of safety - As well as preventing injuries and death, high quality cycling infrastructure addresses both subjective safety and social safety which are of vital importance in encouraging people to cycle.
A second revolution took place on Dutch streets in the late 20th century, transforming streets which were just as clogged by cars as those of other nations.
Pedestrians are well catered for in the Netherlands and pedestrianized shopping streets are common. Usually they allow cycling for access.
Dutch Safety Figures - Cyclists in the Netherlands are the safest in the world, but it has little if anything to do with "safety in numbers".
Sustainable safety - the principles which have lead to Dutch roads, streets and cycle-paths being safe.
A million per hour - The scale of cycling in the Netherlands is enormous. Dutch people make more cycle journeys each day than the entire English speaking world put together.
Campaigning - a collection of posts about how to campaign for more cycling. Primarily campaigning should be for children to be able to cycle. These links include reference to "Stop the child murder", a successful campaign from the 1970s.
What Works - examples of policy, infrastructure and campaigning which have made a different in the Netherlands.
Superhighways - "Cycling superhighways" are not a new idea in the Netherlands
Cycle Paths - Well designed cycle paths benefit all cyclists, regardless of experience or speed
Segregation without cycle paths - you don't always need a cycle path to keep cyclists safe from motorists
Unravelling of routes is vitally important
History - how the Netherlands got to where it is now. See especially "Stop the child murder"
Before and After - views of places before and after they have been transformed for cycling
Directness - examples of prioritising cycling
Traffic Lights - examples of how cyclists can be prioritised and kept safe at traffic light junctions. Note that it's almost always possible to turn right on a red light when cycling in the Netherlands.
Roundabouts - roundabouts in the Netherlands have one very important feature to learn from: They keep cyclists away from motor vehicles. This is far more important than the differences in geometry vs. roundabouts in other countries.
Exceptional infrastructure is always nice to see, but remember that a dense network of mundane routes is far more important to boost cycling modal share
Gritting of cycle paths - dealing with snow and ice.
Children - It may seem hackneyed, but children really are the future. If they can't cycle safely then where will future adult cyclists come from ? This is why children should be the primary focus of campaigners. Note also that according to UNICEF, Dutch children are the happiest in the world.
School travel - Everyone knows that Dutch children cycle to school, but it's a surprise to many people that school trips are also usually by bike.
Cycle Parking - including our favourite design of stand.
Cycle Parking at railway stations, see in particular Groningen and Assen as each have multiple posts showing how the cycle parking has grown over time.
Health effects of cycling
Road Works - It's important that cyclists are thought of when there are road works. If the environment becomes hostile for cyclists then they may stop cycling and never start again.
Commuting - Commuting cyclists are interesting, but they're not the only people who should ride bikes.
Anatomy of a reliable everyday bicycle - the common features of bikes used by nearly every person every day in the Netherlands.
Speed - Some people have the idea that Dutch cyclists are slow. This isn't true. It is just that in the Netherlands, everyone cycles, including the slow people. Fast cyclists are as fast as anywhere. These posts show people who ride faster than average, using the same infrastructure as those who ride slower.

The less positive stuff
What not to do if you want a cycling "revolution" - Long list of interventions and policies which are not helpful.
Copy the best examples from the Netherlands - a short list summarising the above. Important to copy the best examples, not just anything "Dutch". Bear in mind that the Netherlands is not perfect.
Shared Space - this much hyped idea simply does not work well. It disenfranchises the vulnerable and claims of safety are exaggerated. Don't confuse the concept with far more successful nearly car free streets.
Shared Use Paths designed to be used by pedestrians and cyclists together. These rarely work well because the two user groups are too different and it leads to conflicts. They are not built in the Netherlands (but cycle access to pedestrianized zones is good).
Strict (or presumed) liability - If you think this is an important part of why people cycle in the Netherlands then it is probably not what you think it is.
Helmets - one of several ways of scaremongering about the supposed dangers of what is actually a very safe means of transport

Myths about cycling

Long list of myths and Excuses - Various reasons that many people, even existing cyclists, give for why the cycling rate is low in their country, including:
  "our streets are too narrow"
  "it's too expensive"
  "our population is too spread out"
  "we have hills
  "our distances are too great"
  "it took decades in the Netherlands"
  "it's because of the price of gas"
  "it's the weather"
  "Cycle-paths cause indirect journeys"
  "Cycle-paths make people slow"
Cycling is "booming" in Britain - a claim we hear remarkably frequently, but it'll take a lot more than the action taken now before it will be true.
The Truth about Copenhagen - Pretty pictures and nice branding are all very well, but facts are important too. Denmark has no explanation of why the cycling modal share is falling in Copenhagen. The Netherlands has avoided this problem and sets a much better example of how to achieve a high cycling rate.
The Truth about Cambridge - Cambridge in the UK has made claims of being a true cycling city. The city does have the highest cycling rate in the English speaking world, but there are special reasons for its high cycling rate which cannot be copied elsewhere. Most people don't talk about this. I do.
London Superhighways - Unfortunately, London seems to be having trouble coming to grips with the idea of prioritizing cyclists.
Boris Bikes - London's bike share scheme, just like others worldwide, lacks the capacity to make any real change, and makes up for it with hype.