What’s the right number of people to kill on the roads? (Hint: it’s zero)
Zero fatalities sounds nice, but seriously, wouldn’t realizing that vision require us to kill mobility in cities? (Spoiler alert: no)
Also see this article on Medium.com
No more people killed on the roads: that’s what the National Safety Council envisions for the United States by 2050. The NSC’s report “Road to Zero”, released last month, charts out a course to end deaths from crashes. Dozens of cities across the US, with San Francisco and New York City leading the way since 2014, have already been working toward the target of zero. No one could object to such a noble cause… right?
It turns out, not everyone welcomes this project. Take the case of Los Angeles. Last year, to damp down dangerous speeding and make room for protected bike lanes, officials slimmed down a few of the city’s arterials with “road diets”, reducing the number of lanes for automobile traffic; only months later, the city rolled back the safety improvements in response to complaints from drivers. An organization calling itself Keep L.A. Moving declared that the changes “created havoc”.
As this article went to publication, those objecting to the efforts to save lives have not confessed to an overt desire to kill people on the roads. Instead, what drives their resistance is their dismay that many safety fixes work by slowing cars down. To advance all the way to zero deaths would demand such strict controls, one might imagine, that traffic would all but grind to a halt. The National Motorists Association spells it out: the driver advocacy group contends that the “completely unrealistic” goal of eliminating traffic fatalities would mean banning “driving, walking, biking or taking the bus”.
The underlying idea is that there is an inherent, unavoidable tradeoff between mobility and safety. Perhaps the 37 thousand-plus deaths a year on public roads in the US is too many, but 0? That would require sacrificing all ease and convenience of movement. Somewhere in between those two numbers is a happy medium that would offer good mobility and a healthy, sensible number of deaths. Say 18,500?
Fortunately, there’s no need to sacrifice human lives to retain urban mobility. To end road deaths, cities will have to tame unruly traffic, though it won’t be necessary to slow everything to a crawl; beyond that, more people will have to shift to modes of transport that, conveniently, are both safer than cars and provide more efficient ways to get around cities.
For some perspective on safety and speed, step into the shoes of a pedestrian. If you’re on foot and a driver strikes you with their car at 31 mph, your risk of dying is more than twice than if the impact speed were 25 mph and more than five times that at 19 mph, according to Swedish researchers. In other words, even before halving the speed at impact, your risk of death drops more than fivefold. Examining data for cars as well pickup trucks, SUVs, and vans, the AAA Foundation for Traffic Safety similarly found that while a pedestrian struck at 41 mph will probably die, their chance of survival climbs to 80 percent with a 30 mph impact and reaches 93 percent for a 20 mph crash.
That’s still not zero. But we’ve been talking about impact speed; clearly, a driver traveling at a more considerate pace is less likely to run into you in the first place, or at least their impact speed will probably be lower. A driver hitting the brakes at 30 mph will come to a stop 56 feet earlier than if they had been driving at 40 mph; if their initial speed is 20 mph, that cuts another 49 feet off their stopping distance, according to the Transport Research Laboratory in the United Kingdom.
Design remedies like the road diets opposed in LA keep drivers to speeds where crashes are both less severe and easier to avoid. Arterials with wide lanes invite speeding: the Texas Transportation Institute found that drivers travel 9 mph faster for every additional 3.3 feet of lane width. Narrower lanes remind drivers that they’re not on a freeway, as do planters, trees, and benches lining the roadside. Moreover, these and other heavy fixed objects, like bollards, separate massive speeding machines from fragile flesh and bone, preventing everyday deaths and injuries to those on foot and on bikes—as well as deterring intentional vehicle ramming attacks like the recent tragedy on Toronto’s Yonge Street.
Road design that tempers speeds and separates vulnerable humans from automobile traffic is the centerpiece of the “Vision Zero” approach to road safety, initiated in Sweden in 1997. Its namesake uncompromising goal is to end deaths and serious injuries on the roads—which doesn’t necessarily mean eliminating crashes. In fact, some design solutions might result in more frequent crashes. What’s crucial is that the crashes are less severe: at roundabouts, for example, collisions are more common than at signalized intersections, but impact speeds are less lethal. Rather than attempting to eradicate human error, then, Vision Zero strives to ensure that when people inevitably screw up, those mistakes won’t kill or maim.
This strategy works: the yearly per capita rate of deaths on the roads in Sweden fell by over 55 percent between 1997 and 2016. Its death rate is now about a quarter of the American rate. In New York City, which launched its own Vision Zero program in 2014, traffic deaths fell by 28 percent from 2013 to 2017, while pedestrian deaths fell by 32 percent. Over the same period in San Francisco, which also adopted Vision Zero in 2014, road fatalities fell by 41 percent and pedestrian deaths fell by 34 percent.
While Vision Zero is already saving lives, this progress is thanks to measures that tend to slow down car traffic, as lamented by groups like the National Motorists Association. But that doesn’t mean mobility must be sacrificed. Closer analysis reveals that cars aren’t the only way to move people around cities. Nor are they the safest and fittest for urban environments: not only do buses and trains, with their high passenger capacities, move far more people down a given width of right of way than private automobiles can carry, public transit also comes with less than a tenth the rate of deaths and injuries per passenger mile. And when people opt to walk or bike instead of driving, everyone’s exposure to crash risk drops. Cities with many cyclists, for example, see fewer deaths on the road per capita; the fatality rate in bike-friendly Davis, California is seven times lower than the US as a whole, according to a study published in 2011. The presence of cyclists nudges drivers to reduce speed and be more attentive, thus lessening everyone’s risk of falling victim to a high-speed crash.
Technologies on-board vehicles provide an additional line of defense against human fallibility. There are humbler technologies like alcohol ignition interlocks that prevent a driver from starting the car if they’re over the legal blood concentration of alcohol, and intelligent speed adaptation systems that alert drivers or automatically reduce speed when they’re exceeding the speed limit—and then there is the emerging high tech of automated vehicles. Hopes are high that robot drivers will steer a path away from the carnage wreaked by humans. But even after the tech is mature and proven, the no-tech safety strategy of minimizing exposure to crash risk by simply driving less will remain the most powerful. The safest mile will always be the mile not driven.
That’s where it pays to build more compact urban form. Areas with higher residential density and more connected street networks have the lowest per capita traffic fatality rates, according to an analysis of 101 metropolitan areas in the US published in 2003: the fatality rate in Manhattan, for example, was a ninth the rate in a suburb of Kansas City. People in denser areas with better connected streets simply drive shorter distances and, better yet for everyone’s safety, often travel by foot, bicycle, or transit instead.
Still, zero deaths and serious injuries on the roads might seem an unattainable fantasy. Perhaps it would be more reasonable to aim for a level of safety comparable to that seen in other forms of transport. Like flying, for example. Which happens to be closing in on zero: until the death of a passenger on a Southwest Airlines flight in April, US passenger airlines had been fatality-free since early 2009. The last fatality on a UK airline occurred 29 years ago. At a global level, there’s still some distance to go, though the numbers show remarkable improvement: out of the almost 37 million commercial passenger flights around the world last year, the total death toll was 44. [Note added 18 May: clearly the numbers for 2018 will be worse.] That’s compared to 2,469 deaths in 1972, when there were a mere 9.5 million flights. As far as air travel is concerned, then, endeavoring for zero deaths doesn’t seem to have killed mobility. And there’s no indication that getting close to but not quite reaching zero has satisfied the public’s desire for safety—at least, one doesn’t often hear complaints that the trouble with flying today is that too few people are killed.
Eliminating deaths on the roads requires cities to rein in dangerous traffic speeds, no question; but beyond that, it calls for a shift to modes of urban transport that are both more space-efficient and safer, like public transit, walking, and cycling. That means that rather than hindering people trying to move about cities, efforts to save lives could even boost urban mobility along the way. In that case, though road diets and other safety improvements currently face their share of opposition, if cities resolutely commit to saving lives on the roads, resistance to Vision Zero will eventually be about as common as protests against excessively safe airlines today.