Principles of Sustainable Safety in the Netherlands

Guest blog by Mark Treasure. First published on As Easy as Riding a Bike

The N470 is a main road that runs east from the Dutch city of Delft, connecting it with the city of Zoetermeer. It is 12 kilometres long between the junctions with the A13 motorway (bypassing Delft) and the A12 motorway (which runs between The Hague and Utrecht).

From Google Maps

As can be seen from the map above, it is, effectively, a bypass of the town of Pijnacker, bending south around it. Before this road was opened in 2007, a large proportion of the motor traffic running between Delft and Zoetermeer would have passed through the town. Now all that motor traffic is far away from human beings. This applies both at the large large scale – the way the road is built away from urban areas – and also at the scale of the road itself, where, as well shall see in this post, human beings are kept completely separated from it.

This modern road has been built according to the principles of Sustainable Safety, or Duurzaam Veiling – the Dutch approach to road safety. This programme was only developed in the mid 1990s, so it is relatively recent, but it completely underpins the way roads and streets in the Netherlands, both old and new, are designed and built to maximise the safety of human beings. The N470 is an excellent example of these principles in action, and this post will look at them in turn.

Functionality

Perhaps one of the most important principles of Sustainable Safety, ‘Functionality’ means that every road and street in the Netherlands should have a single function – mono-functionality – and that every region should classify their roads and streets accordingly, either as a

  • Through road – for fast traffic, travelling longer distances, in large volumes. Motorways, trunk roads, bypasses, and so on. Roads humans won’t ‘engage with’, by design.
  • Access road – the ‘end destination’ for journeys – places where people live, work, shop, relax, and so on.
  • Distributor road – the roads that connect up the through roads and access roads.

Quite clearly the N470 falls into the ‘through road’ category. It is a road for transporting people from A to B; it is most definitely not a road that people will be exposed to in any form. There are only three junctions between the outskirts of Delft and Zoetermeer, all turbo roundabouts around Pijnacker, which human beings cannot go anywhere near. It is effectively hermetically sealed away from the environment it is travelling through – walking and cycling are entirely separated, via underpasses, and even other roads are again grade-separated.

Here the N470 goes into an underpass to avoid any connection with a rural access road. From Streetview

Homogeneity

This principle applies to the mass, speed and direction of road users. Heavy objects should not share space with light ones; fast objects should not share space with slow ones; and objects should be travelling in the same direction. Differences in mass, speed and direction should be minimised as much as possible.

We can see these principles clearly in operation in the design of the N470 road. Perhaps the most obvious application of homogeneity is that light objects – human beings – are completely designed out of this road. They go nowhere near it. In fact the photograph below is about the closest you can get.

screen-shot-2016-11-02-at-08-43-48

The three junctions on this stretch of road – two at the end, and one in the middle – are all turbo roundabouts, and all have total separation between human beings and motor traffic.

The roundabout at the Delft end of the N470 has signs explicitly banning walking and cycling from the roundabout – but really nobody would choose to negotiate the roundabout at surface level on foot, because of a fast, convenient cycle road to the side, that bypasses it completely.

screen-shot-2016-11-02-at-08-43-13

The roundabout in the middle is another turbo roundabout, again negotiated by an underpass – or, perhaps more specifically, where the road has been built up on an embankment with a bridge.

screen-shot-2016-11-02-at-08-44-11

And the final roundabout at the Zoetermeer end is exactly the same, with two underpasses allowing people to negotiate the arms of the the roundabout, complete with noise barriers. As with the previous example the roads and roundabout have been built up high so that cycling remains at ground level, at the same level as buildings in the neighbourhood. These are bridges, more than underpasses.

screen-shot-2016-11-07-at-00-47-38

I did manage to scramble up the bank here to take a photo of the roundabout – narrow lanes with hard physical dividers, combined with heavy, fast traffic, means that this is not somewhere you would want to be on a bike.

screen-shot-2016-11-07-at-00-49-48Especially when you can bypass it, completely oblivious to the traffic overhead.

screen-shot-2016-11-07-at-00-50-50

But of course Sustainable Safety applies to all users of the road network, not just people cycling. The road is designed in a way to keep motorists safe too.

screen-shot-2016-11-07-at-00-57-49Perhaps most notable is the median between the two lanes, that prevents any attempts at overtaking. The speed limit on this road is 80kph (about 50mph) and that applies uniformly to all vehicles, from HGVs right down to small cars. Quite sensibly, if everyone is travelling at the same speed, there can be no justification for overtaking, and the design prevents people from even attempting to do so.

A couple of years ago the DfT raised the speed limit for HGVs on single carriageway roads from 40mph to 50mph, partially on the grounds that it would (allegedly) reduce the temptation on the part of some drivers to indulge in dangerous overtakes. But the Netherlands has solved this problem at a stroke by equalising the limit for all users at 80kph, and by simply banning overtaking altogether on this category of road (and physically preventing overtaking in new road design).

All Dutch roads of this type have a continuous solid line, forbidding overtaking, and an equalised 80kph speed limit

Overtaking presents an unacceptably high level of danger – it involves vehicles occupying the same space but travelling in completely the opposite direction, at great speed. The opposite of homogeneity! It is much safer to ban it, and to simply design it out of these roads altogether. On the N470 all vehicles are travelling in the same direction at all times, and at approximately the same speed. Overtaking conflicts have been removed, as have any turning conflicts, with no motor vehicles crossing the paths of other motor vehicles – because there are no junctions.

Another implication of the principle of homogeneity is that mopeds (which aren’t capable of travelling at 80kph in any case) are banned from these roads, and instead placed on the cycle path, alongside people walking, cycling and jogging. This makes sense according to the principle of homogeneity – their mass and speed is much closer to that of pedestrians and cyclists than it is to the vehicles on the road.

screen-shot-2016-11-02-at-08-44-18

Forgivingness

Another principle of Sustainable Safety is ‘forgivingness’, which implies pretty much what you would expect from the title. Essentially, mistakes by road users should not result in death or serious injury. Road and street design should account for the fact that human beings are fallible, and will inevitably make mistakes.

We see this principle reflected in a number of aspects of the design of the N470 road. The road lanes themselves are narrow, to help ensure that people do not exceed the 80kph limit, but there are large overrun areas on either side of the road, composed of a concrete mesh.

screen-shot-2016-11-02-at-08-43-52

Probably not very enjoyable to drive over, but if you do drift off the road, you won’t die.

Naturally, forgivingness also applies to people cycling. It lies behind the systematic removal of bollards from Dutch cycle paths, where at all possible. Bollards are not good things to crash into, and can cause serious injury and death. It is definitely preferable to have the occasional driver venturing (either mistakenly or deliberately) onto a cycle path than it is to have a permanent hazard on it, 24 hours a day, seven days a week. It also means that kerbs and other elements of cycling infrastructure should allow mistakes to happen, without serious consequences.

New cycle infrastructure in the city of Delft, with a forgiving, essentially crash-proof kerb

And, of course, at a higher level, the fact that there aren’t any human beings outside of motor vehicles on the N470 road, or even near it, means that cycling is very safe. The fact that Britain persists with accommodating cycling on busy 60 or even 70mph roads is extraordinary by objective comparison – the consequences of errors and mistakes when you have such enormous differences in mass and speed in the same space will be deadly.

Trucks travelling at 80kph on the right; a father with children in a cargo bike, far to the left. These two should not be combined, for very obvious reasons

Predictability

A better way of expressing ‘predictability’ would be ‘instantly recognisable road design’. The users of a road or a street should understand how they are expected to behave, from the appearance of that road or street. The design should be unambiguous. For instance, if you want motor vehicle users to travel at 20mph, the road or street should look like that, and it should make the majority of users travel at no more than that speed.

From the photographs in this post you won’t need me to tell you that the appearance of the N470 will obviously inform its users that it is a through road! There are no junctions; no interactions with non-motorised users; a median; and a design that suggests a speed of 50mph or so. As already mentioned, the design of the N470 should make users travel at or around this speed – the speed limit should be self-enforcing. Design should lead behaviour – we should not expect people to do unnatural things.

Conclusion

In a nutshell, Sustainable Safety is really about a strategic separation of fast, heavy objects from slower moving, lighter ones, across an entire country, both along roads like the N470, passing through rural areas, but also in urban areas. It is universal.

It is noteworthy that there are multiple cycle routes between Delft and Zoetermeer, all of them completely separate from the road network. Some parts of these are shown below. These cycle routes pass through the places where people actually live and work, while the motor traffic is shielded away from human beings. All these routes are more direct than the N470, or alternative driving routes on the motorways.

The cycle route in and out of Delft

Another route between Delft and Zoetermeer, as it passes under the A12 motorway.

And another route between Delft and Zoetermeer - this one an access road (connecting to a small number of properties) that only permits driving in one direction.

So despite the name, Sustainable Safety is not just about safety, but also about creating more attractive and more pleasant places for people to live, work, shop, and relax. People can still drive, of course, and with great ease, but their journeys will be separated to the greatest possible extent from human beings. It is a bold and ambitious project, but one that, despite only being a few decades old, has had dramatic and impressive consequences. We should be paying close attention.

 

You can read more about Sustainable Safety in a number of places –

Advertisements

One comment

  1. That is not a through road but a distributor road. Through roads have raised motorway style barriers and 100-130 km/h speed limits and hard shoulders and their junctions are interchanges, not even turbo roundabouts. Distributors have divides between the two directions, at least paint, ideally a grass or raised but not motorway style medians, it has a 50-80 km/h speed limit, no hard shoulders and can have curbs (although beveled curbed are becoming very common on Dutch distributor roads at 45 degrees for the same reason that 30 degree curbs are being adopted for cycleways), and it should have roundabouts as their primary junction design, secondarily it can have a sign controlled priority junction with last choice being traffic lights, and there are as few crash barriers as possible on distributors to distinguish from motorways and autowegen.

    Like

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s