Are cul-de-sacs a dead end?
Posted: September 22, 2011 Filed under: Planning | Tags: cul de sac, new urbanism, permeability, Toolern, walkability, Wesley Marshall 8 Comments
Cul-de-sacs in the Medina District, Tunisia (Wikipedia)
The New Urbanism hates cul-de-sacs – they’re emblematic of much that’s wrong with car-oriented suburban cities, including poor walkability, low transit provision, long travel distances, “excessive” demand for privacy, and even low social capital.
I might be in a minority, but I’m an admirer of cul-de-sacs. They’ve been around for thousands of years for good reason. I grew up in what in my day was called a “dead end”, 6 km from the city centre. I lived in a terraced mews in Sydney for six years, just 1 km from the Town Hall. I now live in a seven property cul-de-sac developed in the 1950s, 8 km from Melbourne town hall.
The great advantage of cul-de-sacs is they have no through traffic, so they’re quieter and it’s safer for children to play outside on the street. As long as they’re not too long, they can create a sense of place and possibly promote greater social interaction among residents too (although it’s not clear how much of that’s due to the cul-de-sac form; to lower traffic levels; or in some cases to joint ownership of common property). It’s also a matter of no little importance that residents seem to like them.
Another claim is cul-de-sacs reduce infrastructure costs significantly compared to a grid plan. Further, they “allow greater flexibility than the common grid in adapting to the natural grades of a site and to its ecologically sensitive features, such as streams, creeks and mature forest growth”.
Cul-de-sacs are popularly associated with outer suburban developments and that’s why they get such a bad rap. However they can work in a range of urban contexts. They’ve often been used in inner city traffic calming schemes (where they’re called “street closures”). Large, higher density redevelopment projects like this one in Brisbane use what is essentially the cul-de-sac form to give access to dwellings without a street frontage. Yarra Bank Court in Abbotsford would be better with pedestrian access for residents at the far end but is otherwise a delightful “dead end”.
According to critics, the key disadvantage of suburban cul de sacs is they create a circuitous road system, necessitating longer travelling distances. This discourages walking and increases the cost of providing public transport when compared to a traditional grid pattern.
It’s true that many older suburban estates are relatively impermeable. However as inner city street closures show, it is quite easy to design cul-de-sacs that are open for pedestrians but not cars. It’s also quite simple to have a 1 or 1.5 km rectilinear grid of main roads for buses (e.g. see Toolern) with cul-de-sacs confined to “filling in” each square.
I think the main reason cul-de-sacs are demonised by new urbanists is because they’re conflated with the problems of outer suburban development. Consider this quote from Wesley Marshall, an assistant professor of civil engineering at the University of Colorado:
A lot of people feel that they want to live in a cul-de-sac, they feel like it’s a safer place to be. The reality is yes, you’re safer – if you never leave your cul-de-sac. But if you actually move around town like a normal person, your town as a whole is much more dangerous.
Professor Marshall says fatal accident rates are lower in areas with a traditional grid pattern, but he makes an elementary mistake. The traditional areas are older – they don’t have fewer fatal accidents because of their street morphology but because they’re denser, with more mixed development, more traffic and slower travel speeds than outer suburban areas. The primary “culprit” here isn’t the cul-de-sac, it’s the lower density and monoculture of the newer suburbs.
The same article says “people who live in more sparse, tree-like communities drive about 18 percent more than people who live in dense grids”. Again, that’s primarily because of differences in density. For example, destinations are further apart in outer suburbs so residents are less likely to walk or cycle. Given the article refers to the US experience, it’s possible, even likely, that differences in income between the two areas are an important explanatory factor too. At least this time the writer talks about “sparse” communities rather than specifically fingering cul-de-sacs.
As I’ve mentioned before, the trick with cul-de-sacs in the outer suburbs is to keep them short, minimise long looping feeder roads or “crescents”, make the layout porous for walkers and superimpose an orthogonal main road grid to provide public transport within walking distance. None of that is particularly hard yet it would enable outer suburban residents to enjoy the amenity and safety benefits of the cul-de-sac form.
If the objective of policy is to increase the density and mix of uses in the outer suburbs, then that will require an entirely different set of policies, so let’s not throw the baby out with the bath water.
Where they have the option, there’s no reason why new medium and higher density housing developments should eschew cul-de-sacs. Residents of areas like the inner city can enjoy the advantages of this street form and still have the “jumble of apartments, shops and restaurants” associated with traditional neighbourhoods.
New urbanism has a lot to say that makes good sense, but the focus needs to be on better cul-de-sacs, not no cul-de-sacs.
(BTW I know it’s culs-de-sac but that just doesn’t sit right with my ears).
The Melbourne Urbanist 
‘Cash-strapped’ Bayside Council (Victoria) dislikes cul-de-sacs so much… they SOLD one (Barr Street, Brighton East) to a local developer(Gillon) for about $2.3 million at the end of 2010!
At first, Barr Street used to be a was a STREET, then it was ‘transformed’ into a CUL-DE-SAC… now it will be covered with a High-Rise, High-Density development. CRAZY!
This seems to be the preferred ‘Life-Cycle’ for small streets & cul-de-sacs when wealthy developers ‘get their way’!
Why not ‘send’ your local cul-de-sac to Bayside… and they’ll sell it for you. possibly for a ‘commission’?
Count me in the ‘no’ camp. Walkways down the end of culs de sac do allow pedestrian permeability but are very much a second-best option.
For five reasons.
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 to a street 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 and the most number of cars on blocks and sheets for curtains are gathered at the ends of courts. Or if that’s not factually the case it looks worse around the bowl of a court. Look at Studley Court, Laverton on google. And front fences on houses at the ends of culs-de-sac can be casualties of wayward cars as well (and probably bad feng shui!).
Peter, re point 5: Studley isn’t a court, it’s a landing strip! What were the designers thinking – that there needs to be room to turn a semi around?
I don’t know about your speculation that cul de sacs harbour more derelict houses – neighbouring Burke Ct looks better, more typical of the suburb as a whole.
There are low fences along pedestrian walkways in places like Seaside, but yes, I don’t think Melburnians would generally go for them. Perhaps the trick is to design pedestrian ways more like street closures, as in this case.
Even so, whatever the increased risk of crime in the the outer suburbs from short pedestrian walkways is, it has to be balanced against the benefits of removing through traffic. Seems like no contest to me.
There is a quite fascinating book on this topic by Stephen Marshall called Streets and Patterns. He essentially argues that the existing system of road classification is a jumbled mess, and ought to be classified according to compositional, configurational and constitutional properties. In relation to cul-de-sacs, this means essentially what you said above, that it can be constituted as a car-cul-de-sac, but a pedestrian-main-thoroughfare, leading to a configuration that emphasises walkability. As a point of design, cul-de-sac walkways would be better if the houses adjacent to them, fronted the park/walkway, with a narrower street frontage for the garage.
There seems to be a modern fashion for making subdivisions with back fences facing the main road, with no pedestrian paths at all linking to the streets inside the subdivision. For example, see Windsor Rd Kellyville NSW between Macquarie and Samantha Riley. Or the area south east of Buckley/Milleara Avondale Heights Vic. In the latter case a house in Michel Close is 150m from the nearby shopping centre as the crow flies, but 450m by road.
These subdivisions are a disaster for pedestrian, bicycle and public transport access. Yet the damage is so needless and could be avoided so easily by designing in appropriate paths. Why do they do it? Is there something going on that developers think that people prefer the impermeable style to keep out undesirables? Or what?
Councils who allow such subidivisions, while at the same time professing high level policies to encourage active transport (which I’m sure they all do) are seriously conflicted.
Cul de sacs aren’t the problem with regards to crime. Crime is the problem with crime. Bad character. Some people are born evil. We can’t keep changing our urban form hoping this will engineer out bad breeding.
If I was in Singapore and the government proposed building a development at the end of a cul-de-sac, the rattan would sting on the backsides of the crims just the same whether the road was a cul-de-sac or a through road.
The only real argument is the one that some buses can’t get through in these road networks. Again, this will only matter depending on local circumstances. If a bus on a 2km route radiating from a rail station has reached the logical end of the journey, and if the other ‘side’ of the cul is served satisfactorily by another bus radiating to another station, then I can’t see the problme. But there will be times the cul-de-sac is a limiting feature.
Of course, overall low density and car dependency will stuff things up for PT no matter what the shape of the road network
The plural of cul-de-sac is actually culs-de-sac.
Indeed. You must’ve missed my note at the end of the post.