Special Report: Walkable Streets

Cognitive Psychology and Vehicle Speed

A seemingly small difference in vehicle speed can mean life or death for a pedestrian or cyclist, and not just because it heightens the force of impact in a collision. It's not just because physics. It's also because psychology.

By Michelle Martin
Published August 04, 2016

Perhaps I need to disclose an interest before writing about lower speed limits, since streets designed to eliminate traffic accidents involving pedestrians would definitely make my day job easier.

Teaching people with developmental disabilities how to cross an intersection safely would be much more straightforward if pedestrian movement was the priority always and everywhere.

But I also have an interest for my own sake. After all, on the days when I walk or take the bus to work, I count on arriving alive. I have an interest for the sake of my children, grown and not, who walk, bike and take public transit every day.

Actually, everyone I know and love has to walk and cross streets sometimes, even if they usually travel by car. And I don't think it's too much of a stretch to say that we all have loved ones who have to walk somewhere, sometimes. So let's all disclose our interest together.

Speed kills: we know this. We know that the faster a car is travelling when it hits you, the more likely you are to be killed - because, as we learned in high school, Force = Mass x Acceleration.

We know that a big part of the campaign to reduce pedestrian fatalities has been lowering speed limits on city streets. We also know that a posted limit of 50 km/h often translates, in practice, to traffic flowing at 60 km/h or even more.

The unconvinced among us retort that they are good drivers, so they don't hit people and they should be allowed to drive at 50 km/h and faster if they feel they need to. And if a pedestrian makes an error, well, that's the pedestrian's fault.

With Great Power Comes Great Responsibility

There's clearly a power imbalance here: in a serious accident where a pedestrian is "at fault", one person gets a cracked windshield and maybe a "failure to yield" charge, the other ends up dead or seriously injured.

Obviously the onus is on the driver to take all the care necessary to avoid hitting pedestrians or cyclists, whether or not those pedestrians or cyclists are in error.

"With great power comes great responsibility" - this approach to justice that has been around for centuries (no, Marvel Comics did not invent it), reaching at least as far back as the New Testament ("From everyone to whom much has been given, much will be required"), maybe farther, I don't know. Philosophy wasn't my course of study.

I'll stick to psychology for now. Consider what the human brain is capable of doing at any given moment. Think about how much you can attend to at one time. Think about the complicated endeavour that driving is.

When we drive, we have to attend to our own speed and use our car's signals correctly (did you turn off that left indicator?). We have to attend to road signs and traffic lights. We have to judge the speed and distance of other vehicles, including bicycles. We may be navigating an unfamiliar neighbourhood. We have to listen for emergency vehicle sirens. And we have to watch for pedestrians.

We have to take all of these pieces of information in as they occur, and make split-second decisions about how we will respond.

Even the most practiced drivers among us do not do all these things simultaneously. Multitasking was debunked long ago. We may think we are doing several things at once, but we are actually switching very quickly between individual tasks. Adding an unnecessary, immediately unrelated task while we drive can tip the balance dangerously.

Our increased understanding of human cognitive abilities, informed, unfortunately, by carnage on the road, has led to distracted driving laws with large fines attached to them, and rightly so.

Driving Speed and Visual Field

What do speed limits have to do with this? Consider that when we drive, we have to pay attention to road signs, traffic signals, other vehicles, and pedestrians as we approach them. The faster we travel, the less time we have to make a decision and act on it.

And when we increase our speed, our useful visual field decreases. Even if objects or people are in our actual visual field, on either side of it for a split second, we just aren't aware of them. As our speed increases, we experience a kind of tunnel vision.

Driver's peripheral vision at 16-25 km/h (10-15 mph) (Image Credit: National Association of City Transportation Officials, New York, NY, accessed August 3, 2016)
Driver's peripheral vision at 16-25 km/h (10-15 mph) (Image Credit: National Association of City Transportation Officials, New York, NY, accessed August 3, 2016)

Driver's peripheral vision at approximately 16-25 km/h (10-15 mph). Notice how a driver can take in who is on the sidewalk at this speed and, to some extent, at the speed illustrated below.

If you are driving close to this speed and notice a child on the sidewalk bouncing a ball, or riding a tricycle, you've got time to cover your brake and be on guard, just in case.

Driver's peripheral vision at 32-40 km/h (20-25 mph) (Image Credit: National Association of City Transportation Officials, New York, NY, accessed August 3, 2016)
Driver's peripheral vision at 32-40 km/h (20-25 mph) (Image Credit: National Association of City Transportation Officials, New York, NY, accessed August 3, 2016)

Driver's peripheral vision at approximately 32-40 km/h (20-25 mph). A Swedish initiative on road traffic safety called Vision Zero, which sets a standard of zero traffic fatalies that has quickly spread around the world, including to Hamilton City Council [PDF], recommends a speed limit of 30 km/h.

A comparison of the first and second pictures shows why: it would increase the chances of a driver noticing if a pedestrian has just stepped off the curb.

A large number of Hamilton streets (250 to date) have had the posted limit reduced to 40 km/h. One Hamilton neighbourhood has had their posted speed limit reduced to 30 km/h. We aren't the only city to do this.

Driver's peripheral vision at 48-56 km/h (30-35 mph) (Image Credit: National Association of City Transportation Officials, New York, NY, accessed August 3, 2016)
Driver's peripheral vision at 48-56 km/h (30-35 mph) (Image Credit: National Association of City Transportation Officials, New York, NY, accessed August 3, 2016)

Driver's peripheral vision at approximately 48-56 km/h (30-35 mph). In Ontario, the statutory speed limit, or the assumed limit in the absence of any signs, is 50 km/h in urban areas. Many municipalities (including Hamilton) are lobbying the provincial government to reduce it. Our province's chief coroner has recommended reducing it to 40 km/h.

Driver's peripheral vision at 64+ km/h (40+ mph) (Image Credit: National Association of City Transportation Officials, New York, NY, accessed August 3, 2016)
Driver's peripheral vision at 64+ km/h (40+ mph) (Image Credit: National Association of City Transportation Officials, New York, NY, accessed August 3, 2016)

Driver's peripheral vision at approximately 64+ km/h (40+ mph). In Ontario, the statutory speed limit is 80 km/h in rural areas. This picture explains why Highway 5 can be a death trap for cyclists who have no other means of transportation.

It may also prompt you (like it prompted me) to ask yourself how often you've found yourself inadvertently driving 60 km/h on Hamilton streets, like King, Main, Mohawk, Stonechurch or Rymal, and to think about the risk you may have incurred.

Yes, a seemingly small difference in vehicle speed can mean life or death for a pedestrian or cyclist, and not just because it heightens the force of impact in a collision. It's not just because physics. It's also because psychology.

And if you weren't aware of the effect of speed on your peripheral vision before, you are now. Knowledge is power, and with power comes responsibility. Slow down, especially when there may be pedestrians and cyclists around. Because philosophy.

Michelle Martin lives in Hamilton where she and her husband are watching their 10 children fly the nest, one by one. She has been published in both the Hamilton Spectator and Raise the Hammer, as well as in the online edition of the National Post and, more recently, in the Canadian Urban Transit Association's Urban Mobility Forum. Michelle is coordinator of the Community Access to Transportation program. She was formerly on the writing/copy editing team of the original Crown Point hub paper, The Point. However, the opinions she expresses in Raise the Hammer are her own. She sometimes tweets @deltawestmom

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By JWilbur (registered) | Posted August 04, 2016 at 10:24:21

Great piece, thank you!

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By kevlahan (registered) | Posted August 04, 2016 at 12:08:29

Really interesting article that taught me something new about why speeds greater than about 30km/h are risky for pedestrians and cyclists in urban areas. I knew about the shorter reaction times, longer braking distances and greater chance of injuries at higher speeds (kinetic energy increases like speed squared).

But I didn't know about the tunnel vision effect that makes it difficult to see pedestrians or cyclists at the side of the street. It does make sense though: the faster you travel the more you need to focus on increasingly distant objects on the road ... which produces the "tunnel" vision.

Comment edited by kevlahan on 2016-08-04 12:21:26

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By RobMullan (registered) | Posted August 04, 2016 at 20:16:28

While I am fully supportive of reducing speed limits on many of our roads, I think we are skipping past a larger issue - how it has become socially acceptable and practically required to ignore posted speed limits. Most people view the posted 'limit' as a posted 'minimum', and will angrily let you know if you aren't exceeding it enough to keep up with traffic.

We have come a long way as a society in combating the social norms of drinking and driving, and more recently texting and driving. The imposing of huge fines, demerit points, and even jail time or impounding of vehicles have made the cost of intoxicated or distracted driving too high for most people. For sure there are those that still do it, but most don't take the chance because they don't want to pay.

As dumb as this sounds, I believe speeding is the gateway traffic violation to many of the other bad habits drivers have. If you don't have to bother doing what that speed sign says, why bother coming to a complete stop at a stop sign? Or signalling when you turn? Or yield to that bus as it's pulling out?

What's the point of a 40 or even better a 30 limit if everyone still just does 50 or 60?

Maybe it's time to increase the cost of speeding?

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By Brandon (registered) | Posted August 05, 2016 at 08:18:42 in reply to Comment 119770

I think the solution is an engineering one as opposed to behavioral modification through punishment.

People tend to drive at a speed that feels safe, and studies have shown again and again that the best way to set a speed limit is to remove the signs, measure the speed at which people travel and set the speed at the 85th percentile rounded up to the nearest 10 km/h mark. http://onlinemanuals.txdot.gov/txdotmanu...

If people feel comfortable at a given speed and we determine socially that that speed is too fast, we need to change their environment so they feel comfortable at a lower speed. Narrower lanes, street parking, medians, etc... are all means of accomplishing this.

I think our highways do us a great disservice in this because if you've driven on the 400 series highways at the speed limit outside of rush hour, you'd better be in the right lane and be prepared to be passed by most other vehicles.
http://stop100.ca/

This teaches us that speed limits +10 or +20 or even +30 are fine and that speed limit signs don't really mean anything.

Set speed limits properly and enact engineering changes and the roads will be much safer.

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By kevlahan (registered) | Posted August 05, 2016 at 08:44:56 in reply to Comment 119774

I agree entirely.

The fact that 120-125 km/h is more or less the de-facto speed limit on the 400-series highways really teaches people that the posted speed limit of 100 km/h can be safely ignored. I wouldn't be surprised to see a motorist driving a legal 95 km/h being given a ticket for blocking traffic!

The speed limit should be 130 km/h, 110 km/h in rain or snow and enforced extremely strictly. This would actually correspond better to the reality of the design of the roads and how people actually drive. Note that pedestrians and cyclists are not an issue on these roads! It is bizarre that stretches of Highway 6 and other rural roads with non-controlled access have speed limits essentially the same as on a 6 lane controlled access freeway!

On the other hand, local urban streets should be designed and enforced strictly for 30m/h, and a few major arteries designed and enforced at 50km/h. This is the trend in Europe. In fact, Hamilton's arteries are designed for 70-80km/h and enforced at over 60km/h. Even the smallest side street has an official speed limit of 50 km/h, unless otherwise posted.

Comment edited by kevlahan on 2016-08-05 08:45:48

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By fmurray (registered) | Posted August 05, 2016 at 18:16:02

There is another factor on the "behaviour" side of speeding and that is societal pressure. My confession: I used to have a lead foot. I was one of those people who felt my driving was completely safe, but I drove fast. A big factor in creating that behaviour was the fact that I was always under pressure. Perhaps it was self-induced, but consider for a moment what it's like to be a working parent living 30-40 minutes from your work-place. Being held up for a couple of minutes at work meant possibly being late to pick up your child from day care. Add to that dentist appointments, etc. and what you get is high stress -- always feeling like you're 10 minutes behind and people are going to be pissed at you for being late.

Now I live close to work, my daughter is an adult, and I just don't get that feeling of stress anymore. I drive sloowly - 40 km or less on side streets and never over 50 on Main. Except....when I had an evening meeting in Winona, and I was running late. I could feel that pressure again and my brain was telling my foot to press harder on the accelerator. Luckily, I've become conscious of my speed when I drive and I've also learned that being late is not the worst thing in the world. I choose to drive calmly and defensively no matter what.

We need to teach our children that punctuality is over-rated. Yes, you should always try to be on time, respecting other people and their schedules, but if you are late there are worse things. Much worse -- like driving aggressively and rudely through other neighbourhoods.

Perhaps this is a bit pie-in-the-sky, but the world is not slowing down. Pressure on working parents is horrendous and is, I believe, another factor in speeding.

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By RustyNail (registered) | Posted August 15, 2016 at 14:00:19

Cars and people don't mix. Cars and kids are an even worse combination...

As I watch John Tory bungle his way through his own 'Vision Zero' (which started out as a Vision 80-20, as in, 'Well it's OK if we kill 20% of our injured pedestrians...') it seems to me municipalities could greatly simplify their pedestrian safety plans by:

  1. Mandating 30kmh for residential zones and 40kmh for through streets. Make this a blanket approach for simplicity
  2. Setting up speed traps like they do in England (signposted stretches where, if you get caught, you either get points or have to go to 'Speed School' for a whole day (http://www.telegraph.co.uk/news/uknews/1585097/Go-back-to-school-to-avoid-speeding-fines.html)
  3. Set up traffic free zones. Many smaller European cities ban cars from their entire downtowns.

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