If you took a trip by plane in North America this holiday season, perhaps you had the opportunity to look out the window at the city below. If you did, you probably noticed a rather interesting phenomenon: While streets closest to downtown cores are almost always laid out in a grid pattern, the further they are from the city centre, the more geometrically creative they become. In the newest suburbs, roads wind and curve like the branches of a tree.
Most of the oldest cities in North America -- not to mention the grand capitals of Europe -- were designed in neat, densely interconnected rectangular grids that maximized human mobility.
Driven by derision for overcrowded cores associated with pollution and poverty, however, in the 20th century, modernist planners designed places that gave each family a "slice of the countryside," and in so doing invented a new kind of street: the cul-de-sac.
Cul-de-sac communities were sold to North Americans as idyllic compared to the city. They would be private, even pastoral. Noisy traffic would be a nuisance of the past, as outsiders would never need to come down the isolated drive. The centuries-old street grid, with its busy intersections and mix of apartments, shops and restaurants, was dead.
In recent years, however, there has been a growing backlash against the cul-de-sac. Virginia became the first state to limit their use in 2009, and other North American governments have moved or are moving in this direction as well.
There are a number of reasons officials are taking a critical look at the proliferation of this particular type of urban form, but the biggest motivating factor is the ballooning price tag for providing public services. Studies show it is more time-consuming to sweep streets or plow snow in cul-de-sacs, which increases costs. Additionally, secondary roads have generally only become wider over the past few years -- to accommodate the traffic from the subdivisions, schools and office complexes that feed into them. Local governments have difficulty paying the maintenance costs associated with the larger surface areas.
It turns out, however, there may be more reasons than just a fiscal squeeze to reconsider the popularity of the cul-de-sac.
Originally, they were sold to prospective homeowners as an allegedly safer place than along a busy thoroughfare in a grid neighbourhood. No longer a method of getting from point A to point B, the street in a cul-de-sac is used only to reach private residences. The argument was that without traffic passing through, neighbourhood safety would increase; but contemporary empirical evidence suggests this is not actually the case.
In 2011, experts looked at 230,000 car accidents spread over a decade in 24 California cities. What they discovered was while all cities had a similar number of accidents, traditional grid communities had a much lower percentage of deadly ones. In fact, fatal crashes were an incredible 270 times higher in the primarily cul-de-sac areas.
It might seem illogical that interconnected communities are less dangerous, as cars travelling from all directions are constantly in interaction. Such activity, however, forces people to drive more slowly and pay more attention to what is happening around them. When cars, bikes and pedestrians do collide in grid neighbourhoods, they do so at lower speeds, leading to fewer deaths.
As one of the lead authors of the study noted, "A lot of people feel 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, your town as a whole is much more dangerous."
Moreover, a lack of through-roads makes it difficult for emergency vehicles to reach houses sequestered in a web of disconnected dead ends. Fire trucks or ambulances stuck on a major artery cannot take an alternate route through a subdivision, but must stay on the main thoroughfare as the local streets do not meet up, increasing the amount of time it takes to reach a person in trouble.
Certainly, the suburban model that has taken hold over the last half century was addressing real problems of overcrowding and disease. Unfortunately, it seems to have gone overboard, creating a whole new set of issues. The cul-de-sac is perhaps the quintessential symbol of the suburban ideal, but as we tackle contemporary financial and social challenges associated with where and how we live, public officials, citizens and developers need to ask whether it should have such a prominent place in the cities of tomorrow.
In the end, avoiding a curvaceous road plan in favour of the grid system that has served humanity for hundreds of years makes for a less interesting view as you descend into a city from the air, but it might also be one of the best ways of improving safety and reducing the cost of maintaining our urban spaces.
Benjamin Gillies is a political economy graduate of the University of Manitoba, where he focused on urban development and energy policy. He works as a consultant and as a columnist for Troy Media.