A grade-separated roundabout in Rosmalen

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The on-going pandemic still forces me to stay as close to home as possible, which limits my blog post topics. But I do trust many of you will find this interesting: an intersection with separate levels for motor traffic and cycling. The municipality of ʼs-Hertogenbosch is developing a huge new residential area in Rosmalen for more than a decade now. The two biggest intersections of two distributor roads and a main cycle route have become grade-separated. In this post I will show you one of those intersections that was designed as what I like to call a ‘bear pit’.

Inside the ‘bear pit’ of Rosmalen, the lower level of the grade-separated roundabout – that nobody calls a ‘bear pit’ locally.

On Google Earth you can clearly see how the turbo-roundabout on top of the T-junction for cycling looks from above. You can also see that through traffic is kept at quite some distance from the residential streets.

I’ve shown you quite a number of ‘bear pits’ in the country already. The original and name-giving version from the 1940s in Utrecht, the one in Arnhem from shortly after World War II, the one in Eindhoven from the 1970s and two much younger ones from the 1990s in Goes and this century in Sint-Michielsgestel. I’ve also shown you a nearby intersection in the same road and cycle route. In that example the cycle route passes over a turbo-roundabout. That intersection is close to a tall bridge over a canal, which means the height of that bridge could be used to make it possible for people cycling to stay on that higher level. In this case the cycle infrastructure is under the turbo-roundabout because here it means people cycling can stay on ground level and they do not have to cycle up and down a ramp. It is obvious that the designers here are cycling themselves too. They come up with cycle friendly solutions.

The grade-separated roundabout forms the entrance to the new neighbourhood De Groote Wielen. That is why the advertising bill board for the new homes was placed right there.

You cannot cycle east on the main road for motor traffic. The main cycle route east runs parallel to the road for motor traffic but about 150 to 200 metres north of it, right between the houses.

When the new residential area was designed the decision was taken to keep through motor traffic away from the residential streets as much as possible. Motor traffic is directed wide around the residential areas whereas the main cycle routes were deliberately planned to go straight through the streets where people live. I have shown you the main cycle route before, in an earlier post. I also showed you the new bridge in this neighbourhood. Cars only enter the residential streets as close as possible to their end destination. These streets are all 30km/h zones and are considered “space” where cars are guest, while the distributor roads have no other function than a high vehicle throughput. This is a common way to design the main traffic flow in the Netherlands. Especially in areas designed after the Sustainable Safety policies were introduced in the 1990s. In this case the neighbourhood was developed at the same time as the Máxima Canal, a detour for larger ships around the city centre of ʼs-Hertogenbosch. The new canal also required new and rather tall bridges and that was an incentive to completely redesign the main road network. This intersection was built in 2010, around the same time as the canal and the first houses. To maximise the throughput of motor traffic on this intersection where two distributor roads meet, a turbo-roundabout was chosen. Roundabouts are the preferred solution for intersections in the Netherlands, because they are much safer than signalised intersections. Turbo-roundabouts have a higher throughput than ordinary roundabouts and some other benefits. Because the cycle route is also a main cycle route (from this new residential area to the centres of both Rosmalen and ʼs-Hertogenbosch) and because turbo-roundabouts should preferably not have at grade cycle crossings, a grade-separated solution for the cycling infrastructure was chosen; each type of traffic got their own level. There are four arms for motor traffic, but only three for cycling. That is because motor traffic stays on the outside of the residential area (east bound) and cycling is “disentwined” (unbundled) or simply put detached from that car route. There is an eastbound cycle route, but that runs straight through the residential area strarting 165 metres north of this intersection.

Less than 900 metres south of the intersection from this post we find another turbo-roundabout, but this time the cycle T-junction is over that turbo-roundabout to make use of the height of the nearby bridge over the Máxima kanaal.

With the growing tree and the flowers the pit became a bit more attractive. The clean geometry was already interesting but that will appeal to a smaller audience.

I am very happy that the intersection for the three cycle directions was designed as a T-junction and not as a mini-roundabout. We have seen too many examples of failed cycle roundabouts already. The bear-pit of Sint-Michielsgestel comes to mind especially. The silly cycle roundabout in Boxtel is another example. The bear pit in Goes had a T-junction when I filmed it but has since got one extra cycle direction. That T-junction was therefore transformed into a cycle roundabout. That doesn’t make me happy, but I should perhaps visit it again to be able to really judge it.

The completely unnecessary cycle roundabout in Sint-Michielsgestel. A T-junction or a fork would have sufficed here. The design of the turbo-roundabout with a separate level for cycling is rather similar as the one I describe in this post.

The T-junction in the grade-separated roundabout of Goes was replaced by a cycling roundabout. I have only seen that on these pictures from Google Streetview, so I cannot really judge it, but I doubt the cycle roundabout was really necessary.

There is always a risk that motor traffic uses the roundabout the wrong way and to prevent vehicles from falling into the bear pit after a crash, the fence was especially designed to withstand crashing vehicles. The main difference between an ordinary roundabout and a turbo-roundabout is that drivers have to choose their direction before they enter the roundabout circle. Each direction has a separate route on the circle. Weaving from one lane to the other is impossible due to ridges between the lanes. It is also not possible to drive around in circles on a turbo-roundabout. At one point your lane will automatically force you to leave the roundabout. With the potential weaving conflicts out of the way the vehicle throughput increases, but that and the multiple lanes make it undesirable to have level crossings with cycling or walking.

Drivers have to choose a specific lane on a turbo-roundabout. From the centre lane it is possible to drive in all directions, but the outer two lanes only take you to the indicated directions. (Picture from 2015)

I drew how the lanes function. Only from the centre lane (green) you can go in each of the three directions. The outer two lanes, red and blue take you to one direction only. From the blue lane you could also make a 180 degree turn and if you would still stay in that same lane you would even end up in the red route eventually. But it is impossible to drive around in circles on a turbo-roundabout. You will always automatically exit at some point.

The signs with the simple arrows in one of the previous pictures have since been replaced by signs with place names. But the system stayed the same; you have to choose your specific lane before you reach the roundabout. The outer two lanes lead to one direction only.

The first few years this bear pit looked a bit bland and boring. Even with the water way also going through it. Recently I noticed that the grass and the trees are growing and there were a lot of flowers, which makes cycling in the pit a lot more attractive. The sight-lines are quite okay. There are few dark corners where people with bad intentions could hide, but the location of this roundabout is a bit remote. It may not feel socially safe for everybody for instance in the darker hours of winter. The open space that currently exists between the new residential area and Rosmalen proper will be used for a school and big box stores. That will lead to more people in the area and I expect that to further improve social safety.

This week’s video. How does the grade-separated turbo-roundabout in Rosmalen work?