deciphering speed bumps

While travelling recently , I became fascinated about how speed bumps work, and what they reveal about us. If you’re like me, you probably haven’t thought much about them, and aren’t interested in reading thousands of words on the subject. So here’s a point form summary, and you can decide whether or not to read more.



  • We put speed bumps in front of cars so that drivers will hit fewer people
  • They are an uniquely hostile form of behaviour modification, used on mostly law-abiding people
  • Their prevalence and positioning has more to do with politics than traffic and safety planning
  • The delay and damage they cause has not been optimized for public safety
  • This politicized, inexpert approach to traffic flow and safety epitomizes the way Toronto decides bigger issues
  • Adversarial resolution of competing interests wastes time and money
  • A different approach is required to avoid divisive processes and suboptimal outcomes

Now, for the policy wonks and insomniacs among you, here are some further ruminations on these themes…

There should be nothing complicated about speed bumps. They are half logs of cement and asphalt, laid across the road to damage cars travelling more quickly than is deemed safe by concerned residents and bureaucrats.

Still, that’s a fairly complex purpose for a device that has no moving parts. They work by slowing cars to a near stop or by tearing off their exhaust systems. It sounds so simple and effective, it’s almost too good to be true.

Although their effect is on the driver, their benefits are for everyone else, especially pedestrians who aren’t alert or quick enough to cross the road safely. To the extent that they detract from the convenience of driving, demanding extra time and care from drivers, and nothing of pedestrians, they are implicitly hostile to drivers.

If we translate the meaning of a speed bump into words, we are telling drivers that the rest of us believe they lack the judgement and ability not to maim or kill pedestrians in their path. Furthermore, our reliance on speed bumps implies that we cannot pass or enforce laws that will adequately curb their behaviour. It’s an admission that legislation, enforcement, training, testing, and public education cannot match the power of these inert lumps.

The fact that we’ve given up on other means of behaviour modification tells us that drivers aren’t to be trusted. Once they’re behind the wheel, we anticipate they’ll break the social contract that enables us to share space in crowded cities. Only by creating concrete bulwarks can vulnerable pedestrians and dangerous drivers co-exist on narrow residential streets.

Speed bumps cast doubt on whether or not drivers believe as deeply in the sanctity of human life as the rest of us. These bodies of cement laid out on the road act as surrogates for human bodies. Given our fear that drivers are going to hit something, we try to ensure that it’s concrete rather than flesh. Although both will slow a car’s progress, we’d rather replace the car’s exhaust system than replace a beloved child or grandparent.

Whether or not you’d articulate the meaning of a speed bump as I have, it’s hard to escape the conclusion that our reliance on them is a sign of a more pervasive problem. I can think of nowhere else in the public realm where we concede that we can’t draft or enforce laws to protect us from each other and can't train or educate people to respect life. Instead, we build concrete humps on our streets.

It’s not comparable to fencing or barricades that keep people from harming themselves, as in the case of fencing around a rail line, swimming pool, or hydro installation. And, it's not like the placement of median barriers on highways to stop vehicles from straying accidentally into oncoming traffic. Speed bumps are used to correct the behaviour of a group that recklessly imperils the lives of another group.

Where else is such behaviour corrected by building concrete impediments except at the Zoo? Or maybe it compares with the tire puncture spikes that are spring loaded in recesses under the pavement at embassies, prisons, and military compounds. They lurk unseen, ready to shred the bad guys’ tires, whether they be intruders or escapees.

The point is that such impediments are normally reserved for bad guys or animals, which is implicitly how we view ordinary drivers when we resort to building speed bumps to protect ourselves. But are drivers inherently murderous or beastly?

If speed bumps go beyond the capabilities of the law in controlling the behaviour of incorrigible drivers, then we ought to acknowledge a few obvious facts about who these “bad guys” are, and how bad they actually are. That might help us understand the true necessity and value of speed bumps.

First, no one spends more time driving in our neighbourhood than our neighbours and no one is more affected by the retarding effect on local traffic. If we think at all about the people we’re targeting with our speed bumps, we should acknowledge that they’re not faceless strangers who have no stake in the communities we’re trying to protect. The vast majority of encounters with speed bumps involve the people who travel those roads the most: local residents.

Second, the majority of them aren’t habitually speeding or breaking any other law. And, if they were, we would expect a response from the police, not the road workers. According to the City of Toronto, speeds are reduced approximately 20 km/hr at the bump itself, and 15 km/hr between bumps. Add that 15-20 km/hr back to the speed at which cars can safely avoid being damaged (about 15 km/hr, depending on vehicle weight and clearance), and they’d be going 30-35 km/hr, which is less than the standard residential speed limit of 40 km/hr.

My point is that we’ve taken a measure to prevent criminally negligent behaviour and applied it, in the main, to law abiding citizens. Speed bumps are encountered by Toronto drivers millions of times in a year, with most of the delay and occasional damage inflicted on residents of the very neighbourhoods the speed bumps were built to protect.

Speed bumps operate 24 hours a day, seven days a week, 52 weeks a year, whether or not there are any pedestrians or “bad guys” on the road. They delay and damage the cars of the “good guys” mainly, meaning their corrective effect on bad behaviour is proportionally slight.

Perhaps we’ve misjudged drivers and overestimated the net benefit of speed bumps. If so, we add insult to injury by discussing it in euphemisms. Planners and policy makers prefer to talk about “traffic calming,” when what they really mean is “slowing cars.”

Slowing cars by physically obstructing them is a curious was to calm traffic. Cars are meant to take passengers long distances in a short time. Speed and range are their advantages over horses, ox carts, and bicycles. It is Orwellian truthspeak to equate the emotion, calm, with the crude use of concrete impediments against drivers who are lawfully navigating public thoroughfares.

I know that sounds a bit dramatic, but it is nevertheless true. Read the City of Toronto’s explanation of traffic calming, and observe how little is said about measurable safety improvement and how much is said about slowing things down and correcting behaviour (

Note also the City’s explanation of how speed bumps come into being. They are not part of a coherent traffic and safety plan, they result from ad hoc political activity. Residents must complain in sufficient numbers to animate their ward Councillors, who then press City staff to put the bumps (or stop signs, or pinch points, or cross walks) where their constituents want them. City staff can try to resist if the request is unreasonable, but the outcome is nevertheless determined by how strenuously local residents petition the Councillor, and how concerned the Councillor is with re-election.

This abdication of planning to politics is, to an inexcusable degree, what governs traffic flow and safety in Toronto’s residential neighbourhoods. It suffers the same ills as our master planning process, which is constantly harried by the OMB, rapacious developers, and opportunistic politicians. Unfortunately, like most amateur, self-interested, plans or designs, it suffers from unintended consequences.

Because we use speed bumps as an alternative to collisions with people, we equate them with safety. Thus, if one speed bump is good, many speed bumps will be better. Only by this crude reasoning would the City of Toronto be bragging about slowing the flow of traffic, not only where there are speed bumps, but also between them. In many places, there are so many speed bumps, placed at such short intervals, some cars never attain the posted speed limit.

Of course, if this was the main objective, the City could have achieved the same result by taking down the 40 km/hr speed limit signs, and replacing them with 25 km/hr signs, saving the public millions of dollars and reducing driver aggravation. Instead, we have a proliferation of speed bumps, irrationally targeting illusory “bad guys.” To make matters worse, we’ve subtly vilified drivers for being incorrigibly irresponsible, when what is most needed is their sincere effort to share space in a more responsible manner.

We can agree that speed bumps have been successful in slowing cars down, which appears to have become the intended consequence. The unintended consequence of traffic calming is that it makes drivers frantic. That is an observable result of the way we’ve let our streetscapes evolve. While the average speeds may be reduced by speed bumps, we’ve all observed those desperate drivers who speed up between bumps in order to recover lost time.

People can contend with normal traffic volume and regular stops at intersections, provided they can drive at the speed limit some of the time. But put a concrete bump across their path every block or so, and traffic slows unpredictably. Tight schedules constrict until panic sets in, and people try to make up time between speed bumps.

Without making excuses for frustrated drivers, (I cycle everywhere and don’t own a car), it must be admitted that the more we obstruct our streets with bumps, the more tempting it is to speed where there are no bumps. And if you can admit that speed bumps contribute to this state of impeded haste, then you must also admit that the installation of too many speed bumps might, in certain circumstances, increase the hazard they’re intended to reduce.

Returning to the distinction between the objective of slowing cars and the objective of improving safety, I’d like to argue that our promiscuous use of traffic calming devices has dissolved the assumed link between them. As evidence, I offer the cross walk.

Cross walks are built level with the road, not elevated like speed bumps. If we really wanted speed bumps to protect pedestrians, wouldn’t it be logical to put them at cross walks, where we induce pedestrians to enter traffic, rather than everywhere else?

Let me say that a different way: We put up our concrete bulwarks against lawless driving everywhere except at the designated pedestrian crossing points. If the point of speed bumps is to slow cars down for people crossing the street, and the point of cross walks is to create safe places for crossing, why aren’t there speed bumps at cross walks?

Remember, speed bumps are necessary because we don’t trust drivers and can’t adequately police them. Yet at cross walks, where there is nothing except the X-symbol, sometimes illuminated, and sometimes not, we trust the driver not to speed through the intersection. If the message of speed bumps to drivers was, “We can’t make or enforce a law that will keep us safe from you,” the message of cross walks to pedestrians is, “Cross here, the law will protect you.”

Here too, there are unexpected consequences. Who hasn’t seen an angry pedestrian dodging an errant driver who blows past them in the middle of a cross walk? Under certain circumstances, speed bumps induce speeding, and cross walks expose pedestrians to greater danger.

So what would it look like if we brought the objectives of traffic calming and public safety back together?

You might, as some municipalities have, put the speed bumps where the pedestrians are and allow drivers to travel at the posted speed limit everywhere else. The purpose of the speed bump is to add a degree of caution. So, why not add caution to the cross walk by elevating it to the height of a speed bump? When that becomes a standard and predictable feature, the cautionary threat of damage occurs where it is most relevant to pedestrian safety.

Also, you’d take steps educate pedestrians to share the road more safely too, perhaps relocating cross-walks to make them more convenient, enforcing jay-walking by-laws to discourage it in high traffic areas, and handing out lots of speeding tickets to drivers who exceed the limit. There always remains the option of lowering the speed limit, if that was ultimately the intent of speed bumps anyway.

But, from my lay perspective, the prevalence of speed bumps on Toronto streets epitomizes the way we address competing interests. We politicize planning and design, using policy mechanisms that enable one group’s desires to displace another’s, rather than brokering solutions that give both parties more of what they want. Our adversarial approach leads to suboptimal outcomes on large and small decisions.

In the case of speed bumps, the obvious problem is that we sacrifice too much for too little, in terms of travel times and public safety. The less obvious problem is that we sharpen the false conflict between drivers and pedestrians in a City that demands that we sometimes use automobiles and, at other times, walk. (Is it too obvious to note that we’re all pedestrians when we’re not in vehicles?)

The resulting divisions only make it harder to reach fair, wise, and enduring solutions. By fortifying the streets to impede drivers, pedestrians are given license to act carelessly. The conscience and care of drivers, which is essential to any question of safety, is devalued by the use of physical impediments to control their behaviour.

Now you might think, after reading thousands of words on the subject of speed bumps, that I’m making too much of a small problem. However, tell me if you don’t agree that the same divisive and wasteful habits are at work behind Toronto’s current transit and traffic plans.

In defiance of all the experts, aren’t electoral politics behind irrational decisions about the Gardiner Expressway and the Scarborough subway? Isn’t it amazing how, in a time of austerity for the City of Toronto, cost is not an issue, despite a total price tag of almost $2 billion? And, apart from appeasing Scarborough voters, in ridings that all levels of government desperately covet, what have these decisions done to the fabric of civic life in a metropolis that is almost ungovernable already?

That’s why I think speed bumps say a lot about us. We make decisions in a way that dissolves the link between action and intention. We govern ourselves by pitting interest groups against one another, unproductively and unnecessarily, creating empty dramatics at City Council meetings, and tying the hands of qualified planners and designers.

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