Saturday, September 24, 2011

Why even culs-de-sac with walkways are bad

There's been some debate on culs-de sacs. We all know they're terrible for pedestrian permeability.

But is providing a walkway at the end of them a panacea? Some have suggested that this provides the best of both worlds - safety for children due to the removal of through car traffic - and permeability for pedestrians.

While better than culs-de-sac without end walkways, they present some problems. Overall I think they're inferior to a grid streets (with narrowing and traffic calming where necessary).

I give five reasons why in my response to the previous link:

1. Opportunities for graffiti/vandalism. Cul de sacs create blank side fences. These are a canvas to vandals. Urban design that minimises these is good (for the same reason there should always be verges, roads and then houses facing railways – never back fences).

2. Poor passive surveillance compared to a continuous street with house frontages. Increase opportunities for vandalism and assaults against pedestrians. Criminals think they can ‘get away’ with more if there are no sightlines.

3. Low information and legibility. Walkways are less prominent in the street directory and only locals may know about them (compared to continuous streets). Trip planner type mobile apps that only consider streets that cars run on might not have detailed pedestrian access way data.

4. Impermanence. It’s not only in posh areas that cul-de-sacs can be closed. To take a random example, when it was built c1979, the end of Wimmera Court (Werribee) was open.

Now it’s closed and part of private property. Since then a shopping centre opened. Had the end remained open it would only be 10 – 12 min walk from it. Now it’s nearer to 15 min, with the perceived time longer due to less directness. I contend that a legible 10 min walk vs a less legible 15 min walk is a huge difference in walking’s attractiveness and thus its share.

Police and residents may push for closure due to apparent crime problems (see 1 above). But especially if there’s a wider pedestrian access issue that affects others from outside the street, then such calls should be resisted due to its effect on the pedestrian network. But it would have been better not to build culs de sac in the first place.

And I don’t think we should just concentrate on access between schools/shops and houses, even though this carries the higher volume – we should also consider anywhere to anywhere trips – eg kids visiting friends houses.

5. I don’t know if it’s my imagination, but in poorer areas the most derelict houses with the worst gardens, the most number of cars on blocks and sheets for curtains are gathered at the ends of courts. If that’s not factually the case it looks worse around the bowl of a court. Check out Studley Court, Laverton on google. Also front fences on houses at the ends of culs-de-sac can be casualties of wayward cars as well. Though not a believer I do think Feng shui has some good design principles, and I that a house on a cul-de-sac bowl draws the shortest straw.


Riccardo said...

Peter you can name the problem for what it is: housing commission residents, ferals, crime. Social conflict. We live in a tooth and claw 'society'.

Enclosing laneways is as much about the 'freebie' ie getting extra land, as about the excuses given.

But back to the previous point. Do you think we would be even debating it if the country was Japan or Singapore?

Alan Davies said...

Peter, while your points 1 to 4 are all risks (I don't think the fifth point holds water), I don't think they're of the same order of magnitude as the benefits from reducing traffic that a cul de sac can provide. I think they can in any event be mitigated to some extent by design.

mc said...

Re: Alan's comment, the same traffic reduction can occur when you take a street grid and put planter boxes where the traffic needs stopping. This works well in parts of inner Melbourne. It maintains permeability for pedestrians and cyclists, doesn't have the crime problems of an end-of-cul-de-sac lane, and is easy to open up again if needed.

A similar way of doing it when there's no cross road is to put a park at the end of multiple streets.