City of Calgary Bicycle Pathway Speed Limits

This week is the annual City of Calgary bike path "crackdown" designed to ensure the denizens are safe. Certainly a worthy cause.

Having said that, many worthy causes become diluted or misguided when mixed with bureaucracy.

A reminder from physics is that kinetic energy equals half the mass of an object at rest multiplied by it's velocity squared, or K=1/2mv^2. K therefore also approximates "how much it could hurt when the object described by K runs into you". For the remainder of this exercise, I won't even delve into awareness (ie. time to recognize a need to divert course or brake) or braking distance (time to rub off some kinetic energy) or skill (ability to divert course successfully), which are large factors in the real world. We'll stick to velocity, as bureacracies best function by making rules, and for rules to be effective (and revenue generating), measurement is key.

Examples:
Bicycle going 10kph as mandated in certain pathway zones, with the total mass of the bike and rider assumed to be 100kg, has a kinetic energy of 385 Joules.

If that same bicycle is going a more reasonable 20kph as mandated in certain other pathway zones, has a kinetic energy of 1,543 Joules, or 1.543 kJ. Note this is 4x as much (velocity doubled, and it's a square relationship).

A Smart car "fortwo", approximately 1,000kg including a driver, driving 30kph through a playground or school zone within striking distance of our next generation has a kinetic energy of 34kJ. Note this is approximately 90x as much as a bicycle rider's potential to inflict damage.

What about a 2,000kg minivan/SUV driven at 34kph through a playground or school zone, because 30kph is a little slow, and the driver might be a little late, so need to hurry a little, but not fast enough to really get busted too bad. That's an 85kJ situation... or about 220x the destructive potential of a bicycle.

Which is the most frequent event? There are more cars than bicycles, and plenty of school and playground zones. Not to mention more SUVs and minivans than Smart cars.

Dare I even mention awareness again? How about braking distance - a huge relationship to kinetic energy, and bicycle brakes are notably efficient. Or how about skill of evasive maneuver? Moving a bike one foot to the left to dodge a potential collision vs. an SUV...

Which events lead to a greater severity of injury? With all due respect to Lonn and his compound fracture, and the subsequent bicycle collision at the same location a month later that resulted in a broken jaw... how many dead or permanently marred vehicle accident victims would trade their state for a broken arm, even with bones temporarily exposed?

If one took a frequency distribution and multiplied it by potential for destruction (injury), times the likely severity of those injuries, where would the danger zones be mapped? Well that seems self evident.

If a bureaucracy was faced with scarce resources, but the task of keeping the citizenry "most safe" with those resources, wouldn't they be allocated to the areas that do the "most good"?

Nope, that's not how bureaucracies work.

I was pulled over and chatted with by the bylaw officers just to let me know how I was affecting societal safety in my own little way. They even brought up Lonn's incident as justification for keeping the speeds low, because obviously that blind corner, no center line painted, under a low bridge by the zoo is directly applicable to the 20' wide, straight, plain visibility path by Eau Claire.

It seemed to me that discussing the physics of moving objects and the irresistable gravitation of bureaucracies to rule by measureable quantities that may have a proxy correlation to risk with this bylaw officer wasn't going to change the fact that at 6:45am on a sparsely used pathway, I should be riding only as fast as joggers.

For the record, I'm not a pathway blazer intent on proving I can hold over 35kph the whole way home, although they definitely exist... I usually ride about 20-25kph. I use a bell in vain as a good portion of the pathway user community is equipped with bell cancellation devices (iPods).

I'm just happy that we're all moving towards a greater level of safety, and that enforcement of bicycles helps us all.

Hey cops, remember that time I called in with the licence plate of the car who was a) taunting me, then b) tried to run me off the road, and you said that's too bad, because as long as he had tinted windows he was effectively safe with his licencse to knock off cyclists, as I was unlikely to be able to identify the actual driver if I saw him? I'm sure the liklihood that it was the registered owner was pretty low... isn't that good enough a standard to send multinova tickets out with? Oops, sorry. Bureacracy is fine with contradictions, especially when they facilitate revenue.

Thanks. Next time take a picture of my tax dollars being flushed down the district 1 police station main toilet and send it to me, maybe that'll have the same effect.

ps. I'm still bylaw ticket free, unlike that danger at large I live with who got two tickets a few years back. So I'm officially opining from the sidelines.