Thursday, 26 May 2011

Multi-level roundabout - the safest solution for a junction

In my ongoing series about safer junctions I have covered Dutch junction design and how it differs from that of other countries. I then showed you that the Dutch have now discovered that urban roundabouts are safer than cross roads junctions when they are built to a specific design and give cyclists priority.

As stated in that story the first modern roundabout with priority for cyclists was in Enschede and as it turns out Fietsberaad has a file with a lot of background information about this good practice example.

So could it be any safer? Yes, multi level solutions are even better.
Multi-level roundabout in the former-ring road, now inner connector road of Houten
This roundabout in Houten has two levels of completely separate roundabouts. One for motorised traffic and one for cyclists. As you can see in the video there is no conflict at all anymore between these different modes. If you want a junction to be safe this is really state of the art design.

It is not a spectacular video, but you loose the “excitement” on the streets when you eliminate all conflict. It does show how junctions can be made safe to use for all.

This multi-level roundabout was part of the tour of the Australians when we showed them Houten last Saturday. It can be found in the former South part of the ring road of the first new Houten. When new Houten was expanded from the 1990s this road became the only shortcut for cars in the city.

Original Houten in red. The first new Houten (1) and the second new Houten (2). The former South part of the first city ring road is now a short cut between part 1 and 2. The arrow points to the multi-level roundabout.

So is this a rare example? No it isn’t. Multi-level solutions exist all over the Netherlands and they have been around for at least 70 years. The multi-level roundabout in Utrecht in the video below is showing that very clearly. (The roundabout for cyclists was in this case turned into a T-junction some years ago but the zero-conflict situation with the roundabout for motorised traffic remained.)

Of course,  not all junctions can or should be changed into a (multi-level) roundabout. But for some key junctions it can make the essential difference between a pleasant ride and a barrier that cannot be taken.

Why this isn't so important as you might think Exceptional infrastructure like this is always interesting to see, but what causes people to cycle in large numbers is the very tight network of everyday, but high quality, cycle routes.


examinedspoke said...

This kind of infrastructure is beautiful, but almost unintelligible to me. I simply don't see how one goes from what we have now in Los Angeles to that. The changes required are breathtaking: political will, rewritten standards, funding, etc. Making such changes would really require "loosing excitement" onto the streets, and in ways that I can't quite imagine now. But, as always, fingers crossed...

Tejvan Pettinger said...

Very interesting. We have a multi level roundabout near where I live, except it is prohibited to cycle under the roundabout. you are supposed to get off and walk. (It is also prohibited to cycle on the roundabout)

lee said...

There are some junctions like that in England. I believe there is one in rotherham, when I last used it the underpasses were sprawled with graffiti and covered in broken glass which seems to be common with underpasses in Britain meaning they are rarely built nowadays. A cycle underpass in my home town was filled in and replaced with a signalised crossing due to 'social' problems with it.

Anonymous said...

There are a lot of these in Milton Keynes, often with a displaced arm design, the cycle and walk way being turned 45 degrees from the roads resulting in an inner cross roads for bikes. It is a good system although in the past it has been difficult to navigate these routes. Signage has been improved but it remains a very different view of the city.
Mark Garrett, Bristol UK

christhebull said...

And not only are multi level solutions safer, they reduce delays for all road users, which is why interchanges are the preferred option on major dual carriageways and motorways.

However, one should be mindful of the motivation behind both cycle and pedestrian underpasses - are they simply a way to get non motorised traffic out of the way, or do they form part of a genuinely useful network of cycle routes? In the UK, the former is the case, especially in situations where the road is over-engineered in terms of speed for its location.

Guildford has a gyratory system, which as well as incorporating a pre existing street that forms a major pedestrian route and is also home to several bars and clubs, has another section with no at grade pedestrian access.

Of course, pedestrians are not forbidden from this road. They are, however, corrrelled into underpasses and walkways; and therefore it should be noted that whilst multi level solutions may be good at major junctions, those "major junctions" shouldn't dominate town centres in the first place, and the multi level solution is probably better further out where traffic is faster and the safety benefits greater.

Mark Wagenbuur said...

@Christhebull; exactly right. This solution is only suitable for major junctions with a high volume of traffic and not in city centers.
That is what I meant with my last sentence. Both the examples I show in the videos are in (former) circular roads. Social safety in tunnels is always very important. The Dutch also used to have narrow dark tunnels that were terrible, but once they were built wider and lighter they were a lot more inviting. But maintenance is very important! As it is with all (cycle) infrastructure.

Micheal Blue said...

Looks great! They also seem to take lots of space, so proper planning right from the beginning is probably required. And look, Mark, you do have hills - coming from the underpass back to the street level. Mark, since you produce nice videos, it would be great to see one from a hilly portion of your country...if there is one ;-) If you decide to come to Canada, I can give you a free study tour of hills, and show you how to properly run away from a bear. Well, more seriously, there are beatiful country vistas to bike through here, so if you decide to visit, you can let me know.

Anonymous said...

The subject of underpasses in general is actually a good one, the ones I've seen in the UK, for example, have been dreadful. Some of the tricks used these days by the Dutch include:

• Having a wide, gently sloping, open approach right until the point where it passes under the roadway for maximum visibility.
• Sloping walls in the tunnel itself to provide the illusion of width and make it a less appealing place for ne'er-do-wells to hang out.
• Bright lights, obviously.
• Graffiti-resistant tiles in bright colours, preferably largely white.
• A gap between the carriageways to let in natural light.

The tunnels in these two videos don't show any of these advances, as they've been built decades ago.

Mark Wagenbuur said...

@Michael Blue; thanks and yes we do have hills in the Netherlands and I did film some of them. See this earlier blogpost by David:
There is another post too:

@Anonymous; all the 'tricks' you mention are right and used. They can be seen in the second movie in the other tunnels and also in the 70yo tunnels you see the bright graffiti resistant tiles were added recently.

Anonymous said...

I found an example of a well-designed underpass that follows all the current design recommendations in the Fietsberaad Flickr stream. There's various other modern designs in there as well.