xkcd.WTF!?

Explanation ➲

The comic is a parody of a common comparison done in arguments for public transport and walkable cities - the amount of usable space taken up by cars and car-centric infrastructure that could be eliminated for other useful public amenities. The first of these may be from 1965[1].

The first 4 images are common, real-life comparisons involving people walking, people on bicycles, public transport, and cars, which distinctly show how cars take up significantly more space for the same number of people than the other methods of transport. However, from this point the comic becomes more and more absurd in its comparisons.

• The 5th image shows 50 people on what is reported to be a tandem bicycle, although it seems more likely to actually be a string of trailer bikes, due to it not being rigid and the separation from one person to the next is larger than is typical for tandem bicycles. This would obviously be impractical in a city due to the tandem's sheer length and it would not be able to work with fewer than 50 people due to its sheer mass. The longest compound cycle holds 52 people, while an actual tandem bicycle exists that has at least 35 seats.

• The 6th one involves 20 people driving 40 cars, with each person driving 2 cars at a time by straddling them in the middle. Besides being unwieldy and impractical, it would also be extremely dangerous as the cars could go out of control at any time. Perhaps the cars would be a paired mix of left-hand-drive and right-hand-drive models, although with enough push-rods/levers (to also reach the traditional foot controls, and also gear sticks unless fully automatic) this might not be as important. However, even if the cars were perfectly safe to drive, it would be unsafe to drive them on most roads; roads with only one lane per direction are common, everywhere from city streets to exit ramps, and attempts to drive a pair of cars down such a road side by side are unlikely to end well.^{[citation needed]} (Of course, worse than any of these petty safety concerns is the fact that each person takes up twice as much road space, making most infrastructure a bit less efficient. Of all the examples, this is the most wasteful of space, with the entire road being taken up by only 20 people.)

• The 7th one has 30 cars riding on 6 buses by stacking them on top of each other. Assuming the same people-per-car/bus from the earlier examples, this arrangement would have about 345 people riding on the same road! (Unless, of course, the buses are carrying 30 cars instead of their normal passengers.) In addition, people getting out of the cars when they reach their destination would be a problem for most cars in this arrangement due to them being stacked under other cars or surrounded by them. And as in the previous example, it would be impossible to safely drive anywhere without two clear lanes...and the body count would be considerably higher.

• The 8th panel has 50 people in hamster balls. Randall has shown his interest in human-sized hamster ball transportation before, and indeed, for some people, this might be an enjoyable way to traverse a road, provided no other hamster balls try to drive into you and knock you off the road, and other traffic that could pose a greater hazard has been eliminated.

• The 9th panel has 40 tiny cars pulling a big one. Such feats of strengths are a common sight while setting world records, so maybe this is a world record attempt by the cars in question. It is unknown how many people fit in the big car; judging by its size, it likely fits more than a single bus and less than three. It is also unclear whether the tiny cars can fit a human driver, or if they would need to be driven remotely.

• The 10th panel is a 50 person variation on the classic wolf, goat and cabbage problem (which has been referenced before in 589: Designated Drivers, 1134: Logic Boat, and 2348: Boat Puzzle) except this one involves 30 goats, 20 cabbages and 10 wolves trying to cross a section of road that is underwater, using a single boat. The fact that there is a conveniently placed dock at the edge of the water suggests that this is a ford with provision for those crossing by foot, or at least that the road gets flooded often enough to warrant a permanent dock to be installed. It is not known how many people (or cabbages for that matter) the boat fits, but since humans significantly outnumber the goats, cabbages and wolves, it seems like a much simpler problem, though not necessarily without difficulty.

The initial bicycles and singular bus are actually (mostly) using the left-hand lane of the three shown, for whatever reason. This would not be unusual on British highways or other countries using their system, whether the lanes seen are just one of the directional carriageways of a multi-lane split highway or the centre-lane is a gantry-signed 'tidal lane' of a fully two-way street. Yet people who have to walk on a road (due to no footway) are advised to walk facing oncoming traffic (the right-hand side, in the same jurisdiction) and not bunched up. It would be interesting to know why Randall, much more familiar with US road conventions, would have offset these various road-users the way he did (rather than hogging the central lane, or across the entire highway width as he did with the other diagrams in the series).

The title text proposes a problem related to another alternative form of transport — the electric scooter. Randall wonders how well an electric scooter would function when run inside the hamster ball. While this could function like a spherical monowheel, it might also be very dangerous.