How Fast are We Really?
Bring on the Concept of Effective Speed
Judging by the numbers from the Berliner Senat (or from speedometers), cars are a lot faster than bikes. However, a re-evaluation of the way in which we think about speed would have cyclists (and in some cases pedestrians) whizzing by motorists almost all the time: enter the concept of effective speed.
How fast do we go when we move around our cities? For Berlin, estimates of the average speed are about 25 km/h for motorists. But that’s just the average speed from the time a journey begins to when it ends, depositing you at your destination. But when does a journey really begin? Did you have to brush snow off your windshield or pump up your tires? If you walk, did you include the time it took to tie your shoes? Is the last hour you spent at work dedicated to earning the cash to enable your drive home? Or the first fifteen minutes of your income allotted to paying your bike mechanic for the tune-up you got last week?
Traditionally, we measure speed in terms of distance traveled divided by the time it took to travel that distance. That’s how we arrive at ideas like ‘kilometers per hour.’ The most recent data released by the Berliner Senat claims that motorists in Berlin travel at an average of 24.9 km/h. Cyclists, it reports, have an average speed of 12.3 km/h. This difference might seem large, but what if we figure in the time that motorists and cyclists invest in paying for and maintaining their vehicles?
What about all the other things involved in our mobility? The work to afford a car or bike, or time to clean a windshield or pump up tires all adds up, and the number of kilometers to work (or wherever else you’re going) remains the same. It’s time we re-conceptualize our notion of speed. But what should we include when we do? Luckily, some people have already done this, offering us helpful alternatives. ‘Effective speed’ offers us a way to evaluate our speed that includes more of the things that make us mobile in our measurement of speed. Henry David Thoreau contributed to the idea of effective speed in his 1854 book Walden, claiming that if he set out to walk around the world he would be faster than a friend who worked to earn wages to make that same journey by train. And this is what is at the heart of the notion of effective speed: all the time devoted to enabling your mobility ought to be included in your distance per hour calculation.
So we still measure speed in the same terms (distance traveled divided by time), but we include more in our measurement of time than simply the time spent on the journey. A rough calculation of my effective speed on my bicycle is 15.5 km/h (I live in Berlin, earn slightly less than a public employee, bike fast and arrive sweaty). If I owned a car and drove the same distance, using the 24 km/h average of Berlin traffic, my effective speed would be around 8.1 km/h with a Renault Twingo, or 2 km/h if I drove a Mercedes S 500. (Keep in mind, if you earn more than me, you’ll be ‘faster’ than me!)*
I cycle at an average of 17 km/h, earn ~15 Euros/Hour, and spend ~300 Euros per year on my bicycle. The estimated average speed in Berlin for motorists is 24 km/h, and ADAC has estimated the costs of a Renault Twingo at 4,392 Euro/year and a Mercedes S 500 at 24,792 Euro/year.
Of course I can tweak my speed measurement to include the time I spend oiling my chain, pumping up the tires, maintaining my bike or working to be able to pay for the maintenance of my bike, or to buy a helmet or lock, etc. Arguably all this should be accounted for when I think of the speed with which I can travel on my bike. There are some who do very thorough calculations of effective speed. Paul Tranter, an associate professor at the University of New South Wales in Canberra, Australia (one of the very few places where one would really have to cycle very fast to keep up with a car in terms of effective speed), reckons that the money saved by owning a bicycle instead of a car could allow city-dwellers to retire 10 to 15 years earlier. Dr. Tranter writes on effective speed and mobility, using much more exact (and complicated) measurements than I do here. For example, he compares effective speed to social speed, which is effective speed plus external costs. External costs include the costs for streets to be built and maintained, noise control and damage, and the costs of greenhouse gas emissions for society.
Those points aside, he finds that to be faster than a motorist in Canberra, Australia, a cyclist’s effective speed would need to be 21.5 km/h. But that’s the extreme; in Melbourne, Tokyo, or Los Angeles, a cyclist would only need to have an effective speed of around 14 km/h; in Hamburg, 12 km/h; and in London or Delhi, it would only have to be about 8 km/h.*
So next time you climb into your car, bound onto your bike, step onto your Segway, or strap on your sneakers, think about how fast you’re really going to be going, and where your priorities are. Even better, when it comes around to the end of your workday, think about whether that last hour or two is worth it — staying at work to be able to leave in a car. After all, it might not just be 2 hours…it might be 10 years.
*Tranter, P., 2012, ‘Effective Speed: Cycling Because It’s “Faster”’, in J. Pucher and R. Buehler (eds.), City Cycling, MIT Press, Cambridge, Massachusetts.
Originally published at www.urbanist-magazine.com on June 12, 2015.
