This is another post about my recent trip to the Netherlands. The Netherlands has a standard road classification system with ideally three types of roads: flow roads (motorways), distribution roads (arterials), and local roads (residential roads). This system does not recognise roads with the dual functions of through traffic and destination traffic. For example, main streets with a bunch of traffic being funneled through them don’t fit into this framework.
While this classification system works easily with new towns such as Houten, there are challenges with universally applying it across all cities. In Delft they have come up with a fourth road category called a “Wijkontsluitingsweg” or “Roads for living and driving”.
The roads for living and driving were developed because of Delft’s historic street pattern and city structure and competing claims to land use along key traffic circulation routes. This road types resolves the movement-place challenge by establishing key street design objectives of traffic safety, and reduction of noise and air pollution.
Delft’s traffic circulation is enabled by a ring road 4kms wide and one major north-south distributor road. Traffic across Delft follows arterials and wijkontsluitingsweg. These routes work like a grid structure, connecting local neighbourhoods to the big arterials and motorways. The arterials and wijkontsluitingsweg often deviate, directing traffic away from important places. For example, Buitenwatersloot, the main road into the town centre was cut off to car traffic. The traffic was rerouted to an arterial.
In order to address the dual functional requirement of these routes, the wijkontsluitingsweg concept includes the following features: design speed of 40kph, pedestrian safety elements, protected cyclepaths, and roundabouts (not traffic lights). Like many Dutch cities, Delft is removing traffic signals to improve traffic flow and efficiency.
Here are some photos and details of the design of the Ruys de Beerenbrouckstraat. Along the corridor there is special mountable median. This channelises traffic but it is easy enough for cars to turn across. Car parks are set between trees in narrow 2.0m parking bays.
The sideroads have a continuous raised footpath and cycle path which is a standard treatment across Delft. The ramp profile ensures that cars turn at the desired speed. Drivers turning off the road give way to the through-moving pedestrians and cyclists. This is a fundamental road rule, and something that is very intuitive.
Where there is a lot of turning traffic at the supermarket, the sideroad (or entrance) has a different design. The bike path and crosswalk are pulled away from the street which simplifies the crossing for the drivers. Drivers first look for a gap in traffic and turn, and second, look for people walking and on bikes and cross again.
Here’s another look at the residential section. The lanes are 2.65m wide. This keeps vehicle speeds down to the target speed of 40kph. The central median space and ribbon of pavers along the edge allows room for the infrequent buses (2 per hour) and large vehicles. Large vehicle side mirrors overlap these buffers but the travel lane remains tight to slow them as well. Both the cyclepath and footpath are 2.0m, There is a buffer between the parked cars and cycleway of a little less than 600mm.
And here’s a look at a new pedestrian crossing. Before the crossing the asphalt turns to pavers, The carriageway widens a bit to fit in a pedestrian island. The whole crossing is raised slightly, The lane is then funneled into a very narrow channel, about 2.8m wide. People walking can cross with ease since cars are moving slowly and they have such a small crossing distance. People cross in two simple stages. The median is wide enough to fit cyclists who also share the island (or people with prams). Cyclists crossing have to give way to cars and pedestrians. Note the space for cyclists to pause between the cycleway and traffic lane.
There is very little traffic in these photos because the end of the street is closed during construction around the new rail station. This street typically carries about 5,000 cars a day. I think the design approach and details of this particular wijkontsluitingsweg is useful reference in Auckland.
Because traffic is so high in places like the isthmus, many streets have become de facto arterials. Designs like this might be able to serve those in-between streets that now are traffic sewers running through residential areas. I initially thought of streets like Valley-Walters Road in Mt Eden, Fowlds Avenue in Sandringham and Lake Road in Northcote. Some lessons could also be applied to the long 1970’s suburban collectors that are the spines (and barriers) in many neighbourhoods in the south.
Any design will require adaptation to meet our context, in particular the ubiquity driveways. Besides the specific design treatment, I think we can borrow these lessons:
- Proactively reduce the size of roadway space. Cars are small in comparison to the space they are given in Auckland.
- Road design should communicate street function. If you are turning off an arterial (or something like a wijkontsluitingsweg) the roadway characteristics should reinforce the change using ramps and a raised cyclepath/footpath.
- Pedestrians crossings need to be designed better (see above), Proper designs would be more expensive than plonking an island and some buildouts in the street, but much less expensive than signals.
- Keep the kerbside parking, but put it in bays and in-between trees. Providing kerbside parking removes the demand for off street parking (and the associated kerb cuts and driveways). The trees and bays keep the roadway narrow even if everyone drives off to work for the day.
- Trees everywhere, and right up to the intersections. You can see above that proper street trees do not obstruct visibility anymore than a light pole. Trees help to enclose the roadway slowing traffic and improving the look and feel of the street.
- Make the street efficient, but tolerate delay. Will cars turning off the street slow traffic? Yep. Will buses stopping in the lane slow traffic? “Who cares”, as the planner in Delft says.
- Roadway design should reinforce the habit of turning traffic giving way to through moving traffic. I know there are legal issues, but we need to get over it. No one knows the road rules. It’s time to design streets where roadway geometry enforces this desired behaviour.
That’s it, and I didn’t even mention speed limits. Here’s a video of the corridor.