Photo: WCBV Boston

Another major city has lowered urban speed limits in an effort to make its streets safer. As of Monday, Boston’s default speed limit dropped from 30 miles per hour to 25, about the same as going from 50 km/h down to 40. The move is part of Boston Mayor Martin Walsh’s Vision Zero commitment.

Vision Zero is traffic safety philosophy that acknowledges the inevitability of human error, and focusses on designing systems so that common mistakes don’t result in major injuries and deaths. The city of Boston’s announcement explains how the lower limit fits in to its Vision Zero mission:

Legislative efforts, like lowering the speed limit, combined with enhanced street design, education and enforcement policies work together to create a street system and standard of behavior [sic] that dramatically reduces the consequences of everyday mistakes. Mistakes can and will happen, but they should not be deadly or lead to serious, life-altering injury.

Right now, Halifax is perfectly poised to consider a similar move. Our new 10-year transportation plan (Integrated Mobility Plan, or IMP) is in its final stages, and with it, we will be asking city staff for the next decade to embrace the idea that our streets are meant for people of all ages and abilities, using all modes of transportation. We will be reclassifying roads to better reflect their actual use, and further using modern street design tools to make them safer and more efficient for all. The IMP promises to bring the reign of vehicle traffic flow as the priority in our cost-benefit analyses to an end. Moving cars is no longer the end game. In fact, the goal is to move less of them.

I can think of few simpler and more useful ways to express this new value system than to follow the lead of cities like Boston, New York, and Montreal, and reset our default urban speed limits.

Let’s draw a line around our urban streets, the areas where large amounts of pedestrians, cyclists, buses and cars mix, and collectively state the need to slow down.

There are parts of Halifax and Dartmouth where walking and cycling are the primary ways people commute.  It’s time that the laws of our streets reflected this mixed mode reality.

Halifax Mobility Map (download), from The green slices of the pies indicate active transportation as the primary commuter mode in each zone. Yellow indicates motor vehicle, and blue indicates transit.

We need to have a conversation about this: We need to talk about how certain streets, even within our urban core, are designed for speeds above 50 km/h, while others are designed for speeds well below. We need to determine once and for all which is worse: to perpetuate the idea that it’s safe to drive 50 km/h everywhere in the city, or to have to work towards actually building our streets to match our new values.

We need to talk about the fact that changing blanket regulations like speed limits in isolation won’t necessarily change driver behaviour. And so we also need to talk about how to bring our street design in line with our values. The law doesn’t work in isolation, but the law should reflect our collective ideal. And right now, our blanket limit of 50 km/h is too high for safe mixing of modes that we have decided time and again we want on our streets.

The current speed limits in Nova Scotia have been set using something called the engineering method, which relies heavily on a measurement of 85th percentile speed. “That’s basically the speed at which 85 per cent of your traffic is going at or below,” provincial traffic authority Mike Crofts explained to me in June when I last wrote about speed limits. “The thinking behind that, and this has been studied to death actually, is that 85 per cent of your drivers drive at a safe and prudent speed. They’re reasonable drivers. That 85th percentile speed is often a key determinant in setting the speed limits.”

The 85th percentile method simply measures what drivers do. That means 15 per cent of drivers go faster. The premise is that people are reasonable and know what’s safe — that we can feel when our speed is getting dangerously fast.

My question about the 85th percentile method is: What if average people driving cars are wrong? I mean, I trust my instincts while driving will kick in to protect me and my car, but will they kick in in time to protect a teenager crossing the street or a cyclist beside me?

What if the idea of “safe and prudent” from a person seated comfortably in a moving metal box is different than the idea of “safe and prudent” from the average pedestrian? What if, in the decades of using the engineering method to determine speed limits, we have failed to update our own premises, like what exactly constitutes “safe and prudent”? How many traffic injuries and deaths do we accept at “safe and prudent” speeds?

The traffic safety capital of the world, Sweden, has long since abandoned the engineering method of speed limit setting. The originators of Vision Zero way back in 1997 use a “safe systems” approach, where the goal of injury minimization is key. For a deeper look at the very interesting thinking behind Vision Zero, check out this interview with Swedish traffic safety strategist Matts-Åke Belin.

We also use 85th percentile speed to determine if we have speeding problems on streets. Maybe, instead of measuring vehicle speeds to determine where there’s a speeding problem, we should instead be interviewing pedestrians and cyclists. They are much better poised to have a sense of what is “safe and prudent” on a mixed-mode street, after all.

From page 5 of Speed Management, A Road Safety Manual, published by the World Health Organization in 2008. Their source: OECD/ECMT Transport Research Centre: Speed Management report, Paris 2006.

Of course, Halifax cannot single-handedly reset the default speed limit. We need approval from Mike Croft, the provincial traffic authority, who has traditionally said no to municipalities looking for speed limit changes on isolated streets.

But with the IMP, Halifax is setting a new direction for how we move people around the city, and we are committing to changing our streets to better match our values. We will have centrally organized, comprehensive design goals for our streets. A reduced default speed limit as part of the IMP could stand a chance of being approved by our provincial traffic authority.

At the very least, the IMP should be starting this important discussion.

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  1. Speed limits are easily enforced approximations to good driving judgement, but they are not the same thing. I see them as legal expedients.

    Like double yellow lines, speed limits nominally set out to fake good diving judgement in people who might otherwise lack it. Could you imagine the cost and wasted time of courts crammed with people charged with poor driving judgement? which police would have to prove to meet even the low test of ‘the balance of probabilities’, much less that of ‘beyond reasonable doubt? Such charges would be laid in only the most egregious, easily proven cases.

    On the other hand, being deemed guilty on site by a traffic cop citing a Lidar of exceeding some rather arbitrary number saves court costs and implemented the right way can be quite lucrative (especially in jurisdictions with traffic light cameras). The right of an accused to argue they were still exercising good driving judgement although exceeding the speed limit is naturally forbidden.

    I believe there are plenty of open, straight sections of highway one could drive at even 200 km/h without hugely increasing the risk of an accident. There are also sections of 70 km/h road you would be nuts to drive at that speed when deer are out or in blowing snow. Factors other than designed safe road speed that determine speed limits are people’s apprehension that they or their kids would be at heightened risk walking along their street, complaints of neighborhood noise or increased greenhouse gas emissions and these often do have merit, especially where there is likely to be a lot of pedestrian traffic. Still…

    Metro Transit being what it is, I believe cars are essential for many people to get around in HRM, and I don’t see that changing any time soon. Roads have always been more dangerous places than living rooms. That’s just life and it’s not going to change. Forcing down speed limits to reduce accidents a little more (based on curious statistics) is just going cause further aggravation IMHO. That rarely leads to good driving judgement.

    In my experience most NS people drive 10-20 km/h over speed limit on the highways and nearly all of them (and everyone nearby) survive almost all the time. These are people voting with their accelerator – literally road democracy in action. Whatever the official speed limit, I consider that the true road speed.

  2. My favourite example of speed limits in the HRM is the bit of St. Margaret’s Bay Rd from the 103 to the rotary. The first stretch has some curves but runs past a lake and a forest, and has a speed limit of (mostly) 80 km/hr. The piece between Northwest Arm Dr and the rotary has a fairly steep grade, multiple crosswalks, sharp curves, and lots of unmanaged intersections with driveways and residential roads. It has a speed limit of 50 km/hr. Given that this is one major route onto the peninsula, the limits are,in my view, reasonable for most driving conditions.

    The number of people who drive 60 in the 80 zone AND in the 50 zone is amazing to me.

    It’s amazing because I can usually understand why people drive the way they do, whether they drive well or poorly. But these people clearly aren’t driving a speed based on judgment of what is reasonable in the given conditions and road design. They aren’t basing their speed on limits. They aren’t basing it on being in a hurry, or on sight-seeing in no particular hurry. It seems to be based on a level of skill equivalent to “I press gas, car goes zoom”: mindlessly going through the motions of driving while being completely oblivious to be world around them.

    My point is given the people oblivious to the world while driving, I’d suggest rather than mucking about with default speed limits, to identify the roads where slower speed will make the most difference and go all out with signage and enforcement at 35 km/hr. Spring Garden, University Ave, Barrington, Gottingen. As a frequent pedestrian and frequent driver, I’d rather see that resourced than a half-hearted effort at keeping people to 40 on Joe Howe at midnight.

  3. The frequency of car crashes, injuries, and deaths suggests that the “safe and prudent speed” is anything but. When a plane crashes, it’s big news, but we somehow overlook the auto equivalent of a 767 crash (in Canada) every month. Part of the problem is language – we talk about car ‘accidents,’ as if they were unavoidable. Lowered speed limits, strictly enforced, and supported by changes in road design, would improve safety for everyone, and help shift us away from car dominated culture.

  4. We need lower speed limits. Absolutely. I’m encouraged that the Transportation Standing Committee, at Lorelei Nicoll’s request, got the ball rolling last month. If all goes well the city will ask the province for the power to set its own speed limits, removing the need for provincial oversight, by amending the Motor Vehicle Act.