A new town is being designed at Cherrywood to provide housing for 20,000 people and workplaces for more than 10,000 employees, all clustered around the Luas line. Many of the homes are due to be completed by 2019 and in a time of severe housing shortage, this is very welcome.
The developer applied in December for the first phase: the roads and drainage and the parks. The way we plan the transport for our city districts is directly linked with the future quality of life for the residents. So let’s try and get it right! In this post, I examine part of the road layout that the developer has proposed to find the good and the bad. Please let me know in the comments at the end what you think so that I can take your views on board when I make a submission to the council.
There are only a couple of existing roads in Cherrywood: an access road to the M50 motorway and a road joining the residential area to the office blocks. Where these two roads meet is a vast roundabout which provides a soulless hole as the focal point of the district.
There is no way to cross this roundabout on foot. By bicycle it is extremely hazardous. That’s because it was designed with just one goal: to maximise the volume and speed of cars passing through. The clear message to anyone using this junction is to always choose to drive.
So what has the developer planned to replace this roundabout? Look below:
It’s one of the largest signalised junctions imaginable with up to nine parallel vehicle lanes at one point. There is a partial bus lane in one direction that leads straight into a traffic island:
There are pretty coloured bike lanes on all sides which will be great so long as you are always turning left. Mmm, what happens if you want to go straight through the junction from the top right of this map to the bottom left? It looks like you would have to get off your bike and push through four separate crossings and three traffic islands.
The problem is that we have a major motorway exit serving South Dublin passing through a future residential district. If it goes ahead as above it will divide the district and encourage future residents to drive for short local journeys.
The M50-N11 link needs to be physically separated from the local routes. It could be:
- buried in a cut-and-cover trench,
- or elevated
- or left at the same level but with the surrounding streets elevated
All of these approaches are in use in other countries so how do they look?
Last year, I spent most of a week in the Netherlands studying how the Dutch get cyclists and pedestrians safely through junctions. I was accompanied by Irish road engineers while Dutch city officials showed us what had worked and what hadn’t in the past decades.
A bog standard Dutch roundabout
A normal Dutch roundabout is encircled by a separate bike ring. At each roundabout exit, there is a wide crossing for bicycles and pedestrians.
Cars must give way to bikes and pedestrians when entering and exiting the roundabout and they really do! So, people on bikes don’t have to stop as they pass through a roundabout and they are separated from the circulating cars and trucks. Where they cross, the angle between the bikes and the cars allows for good eye contact between driver and cyclist.
Here’s a video to show how it works in practice:
Sadly, Dún Laoghaire-Rathdown County Council (with the NTA) attempted to build such a bicycle friendly roundabout in 2011 in Killiney and made an utter hames of it. The design was dangerous and inconsistent with the above standards. There was no local consultation and utterly inadequate promotion and communication to other road users. After a few months of public opposition and at least one serious collision, the council decided to switch it back to the way it was and tell cyclists to use the pavement instead. The total cost of this outing was about €500K.
Three ways to get pedestrians and bikes through a major junction
The basic roundabout above won’t do in a place where there is a very high volume of vehicle traffic. So let’s look at what does work.
- Elevate the bike lanes
Here’s a junction I visited in Eindhoven (home of PSV), called the ‘Hovenring’. Cyclists and pedestrians use a completely separate ring, floating above the road beneath and suspended by steel cables from a central pole.
It cost about €6m to construct. Given that the Cherrywood development will cost more than €2bn, this may not be an unreasonable amount. It is amazing and beautiful to see.
2. Elevate the major roads
We could also raise the roads as they cross the junction and allow the bicycles and pedestrians to go underneath. I saw a good example of this in Houten near Utrecht.
In Ireland, our experience with underpasses is that they have been a complete failure. Frightening and dangerous to use, the two underpasses in Blackrock were eventually filled in. The underpasses in the Houten roundabout design are more like going under a bridge: they have plenty of natural light and there are good sightlines from all around. The video below, shows you the view from a bike:
3. Physically separate the motorway access road from the local roads
In this alternative, we would run the motorway access road under or over the local road at the junction. this could be done using a ‘tight diamond interchange’
Here’s a planned junction in Amsterdam with the major road separated from the minor road and the bike lanes.
This could be an answer for Cherrywood, with the motorway access road in a trench and the local roads at surface level.
Twenty-five ways to get bicycles across a main road junction.
The Dutch town of Den Bosch has a ring road with 25 junctions, each of which may be safely crossed by bicycle. Here a video that shows that there are many different ways to do this – however none of them look like the Cherrywood proposal !
One of the goals of the Cherrywood new town is that the town will be laid out in such a way that people will choose to walk or cycle for most local journeys to the shop or to school. If we design the roads so that it makes more sense to always drive then, this goal won’t be achieved.
The planning reference number for the Cherrywood road design scheme is DZ15A/0758
What do you think?