Walk, bike, or drive? The efficiency of getting around

 

It’s summer, which means I’ve been commuting by bike. I’ll do anything to avoid the TTC (Toronto Transmit Commission, which runs the city’s public transportation). If you’re from Toronto, you know why.

I see people going to and from all sorts of ways. Cars dominate, but driving isn’t the only way to get around. Many bike. Many walk. Some skateboard or rollerblade. Others (if they’re like my dad) take any opportunity to hop on the Vespa.

I often think about the weight of my bike — my chosen method of transportation — because I have to lug it down a flight of stairs whenever I head out. But it got me wondering, “How efficient is riding a bike in terms of weight?”

More specifically, I wondered how my weight compared to my bike’s weight. I’m heavy compared to my bike, which is around 20 lbs, so I figured biking was a pretty efficient way of getting around. Especially compared to cars, which weigh a lot, but usually transport a single person.

I decided to investigate.

Weight, keep reading

To compare different modes of transport, I calculated the weight efficiency of each one. I have no idea if it’s a real term that I’m misusing, but I calculated it as follows:

Human weight / (Human weight + Vehicle weight)

In other words, assuming each mode of transport carries one person, what’s the human’s weight as a percentage of the total weight, including the human?

vehicle-weight-efficiency-1

I chose 11 vehicles. Five of them are human-powered:

  • None (walking) [weight]
  • Rollerblade [weight]
  • Skateboard [weight]
  • Racing bike (Cervélo Rca) [weight]
  • Mountain bike [weight]

The other six are engine-powered:

Human power vs. Vroom vroom

It looks like there are two main groups of efficiency, which are neatly broken into human-powered vehicles and engine-powered vehicles. We start at 100% when walking, then slowly drop until we get to 87% efficiency with a mountain bike.

vehicle-weight-efficiency-2

Once we strap an engine on, efficiency drops to 43% efficiency with the Vespa, then again to 18% with a motorcycle. After that the efficiency loss tapers until the most inefficient vehicle, the Ford F-150 truck, at 4%.

vehicle-weight-efficiency-3

Even the Smart Car, which is one of the lightest cars you can get, has a weight efficiency of 8%. That means that, assuming you’re just getting yourself from Point A to Point B, the vast majority of energy is being used to move the method of transportation instead of the thing that’s being transported.

Here are the two groups again, for comparison.

vehicle-weight-efficiency-4

 

Not so fast

If we look at weight efficiency, engine-powered vehicles are a silly way to get around. But we all know that there can be a big difference between hopping onto your Cervélo and hopping into your Ford F-150.

Engine-powered vehicles have two-and-a-half big advantages I can think of:

  1. They’re fast. If I’m making a long-haul trip, walking and biking become less and less appealing. For example, it takes 2 hours to drive up to my family cottage and 10 hours to bike…and, since I know you’ll ask, 33 hours to walk.
  2. They can carry lots of stuff. You’d be surprised at how much you can pack on to a bike, but once you reach a certain point it becomes too much. Some things are easier to transport by car, like passengers.
  3. They keep you comfortable. I live in Canada, which can get cold. Cars have climate control.

(Point 3 only applies to some engine-powered vehicles — Vespas and Harleys weren’t designed for Canadian winters — so I only gave a half-point on that one.)

 

It’s a complex issue

Weight efficiency is a narrow way of looking at methods of transportation. Many factors go into the “how do I get there?” decision and I’m not arguing that just because something is more weight-efficient means that it’s the right way to travel.

It is striking, though, that even the least efficient human-powered method here (mountain bike @ 87%) is twice as efficient as the most efficient engine-powered method (Vespa @ 43%). Something to think about on your next commute.

 

Update: I’ve added some information on public transit

Someone pointed out that they’d like to see information on public transit. Here you go!

vehicle-weight-efficiency-5

The efficiencies in the graph are based on the seated capacity of each vehicle. I decided to use seated capacity, instead of maximum capacity, because I thought it would more closely represent average usage. Plus, using maximum capacity for a bus and not for a car wouldn’t really be fair.

Specifically, I added:

  • Bus (Nova Bus LF series) [weight]
  • Streetcar (CLRV variant) [weight]
  • Subway (single car) [weight]

And, once again, here are each of the groups.

vehicle-weight-efficiency-6

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