Engine Summer

It's possible, even in surprisingly ancient times, to have hugely sprawling cities -- but they're not quite the same type of sprawl we see today. The reason is simple: how are you going to get around?

A city that is a mile or so across can be traversed on foot in half an hour, give or take, depending on how fast the individual in question walks and how much traffic and crowding get in their way. Two miles, you can cross it in an hour, or get from the periphery to the center in half an hour. And when you look at historical cities in places like Europe, you frequently find that's about how big they are. One to four square miles is a manageable size.

Cities with a larger footprint did exist, but they require you to change what you imagine when you think "city." It's more like the agrarian version of suburban sprawl -- and, as Annalee Newitz mentions in Four Lost Cities when discussing Angkor, there's some reason to think that pre-modern urbanism in tropical areas simply looks different than it does in temperate zones, due to differences in agriculture. Lidar surveys indicate that Angkor may have covered three hundred and ninety square miles! But that's not a thousand square kilometers of densely packed buildings surrounded by a wall; that's a complex patchwork of fields, houses, temples, and markets, connected by the complex works of irrigation infrastructure that were necessary to maintain it all.

That infrastructure points us toward one possible solution for getting around an enormous city: go by water. I've mentioned before that water transport is often more efficient than land until you get motorized options . . . but when it comes to cities, that's far from a perfect answer.

See, odds are good that you'll be more reliant on muscle power to move the boat, with a paddle, oars, or pole, rather than being able to benefit from natural forces. A river's current will carry you downstream just fine -- but going home? Now you have to fight that force. (Unless the river is tidal in that reach, but then you're constrained to the timing of tides.) And within an urban context, you have much less space to maneuver about with wind. Don't get me wrong; water is still often better. One or two people can operate a boat full of produce brought in from an outlying field, as opposed to needing to wrangle a draft animal for a cart or being limited to what they can carry on their own backs. But it's not as dramatic of an improvement as being able to sail an entire ship or barge hundreds of miles for long-distance transport.

I'm talking about produce because that's going to be the most common reason people in a large city need to move around. (Other goods, too, but food is the first ten items on the list of "what needs to be transported in or the city dies." Water pretty much has to be there already or the city is dead to begin with.) Commuting of the sort that's a dreary feature of daily life for many people in modern times was vastly less common in the past, because most people lived at or very near their places of work, i.e. within walking distance.

This starts to change with the Industrial Revolution -- but not because we got motorized transport, not right away. Instead you started having factories that employed huge numbers of people in a very small area, and while some of them had associated lodgings nearby, the explosion of urban populations as people came thronging there for work meant that density became horrifically unmanageable. Cities had to spread outward, and somebody had to come up with a way to move people around faster.

Early on, the answer to this was the horse-drawn omnibus. (Which is where we get the word "bus" from; in older works, you see an apostrophe marking the bit we dropped, as 'bus.) They were essentially the same idea as the hired coaches between cities, just repurposed for urban use and focused far more on moving passengers than luggage. They also didn't require buying a ticket in advance, instead having the kind of hop-on, hop-off service we're used to nowadays. As the nineteenth century progressed, many of them became double-decker buses, with passengers sitting on the roof as well as inside the carriage -- though the top was usually only for men, as women would have more difficulty climbing the ladder in their dresses, and be exposing themselves to up-skirt ogling besides.

The earliest attempt at this was in the seventeenth century . . . so does that mean it could exist in any era? Perhaps, but I suspect the answer is that it's unlikely. The challenge of the omnibus is making it sturdy and stable enough not to be a hazard to its passengers -- at least, by the lax safety standards of the Victorian era -- and also making the service profitable. Industrialization meant it was easier to produce steel for things like braces and wheel rims, and the sheer scale of demand for transportation allowed for entire networks of routes, rather than just one line that might or might not see enough use. Earlier eras are not going to offer the same favorable conditions.

Of course, we didn't stop at horsebuses. Laying down metal rails in the street greatly increased the amount of weight the horses could pull (and gave passengers a smoother ride to boot); then we got engines that could move the trams in place of the horses; then we realized we could put the trams underground, where traffic wouldn't slow them down, and we were off to the races with subways. Meanwhile, motorized water transport made regular large-scale ferry services possible, without having to worry as much about the vagaries of current, wind, or tide.

Expanding public transit made it easier to expand cities, because now people could live farther away from the noise and the stench, without spending half their day getting to work and the other half getting home again. Even now, though, it can often be an imperfect solution, because not all areas are equally served. If you look at a map of the London Underground, you'll see that while the north side of the Thames has an abundance of lines, the southern bank -- where there are fewer elites and important institutions -- has vastly less. It isn't always the case, though, that elite = access; where I live, in the San Francisco Bay Area, the residents of wealthy Marin County to the north consistently oppose efforts to extend public transit up to their neighborhoods, because then the hoi polloi could get there more easily.

I should note in closing that public transit is not always mass transit. Our modern taxis and pedicabs are the descendants of horse-drawn hackney carriages and human-carried sedan chairs for hire, both of which became common long before we had omnibuses running regular services for large numbers of people. Those more individualized options really only require enough urban density for profit, and enough people with the money to pay for them -- you're not likely to see them hanging around slums waiting for passengers. (Even today, it can be notoriously difficult to get a taxi in a bad part of town.)

And, as usual, speculative fiction throws a few wrinkles into the mix! Science fiction often includes mass transit, because most of it assumes both the technology for such a thing and populations on a scale to make it necessary. Fantasy, by contrast, often leaves it out -- but it doesn't have to! Depending on how magic works, you could have self-propelled vehicles, animated constructs pulling them, even regular flying carpet service from the suburbs to the urban core . . . or no magic at all, beyond the straightforward ingenuity of past invention.



(originally posted at Swan Tower: https://is.gd/W9jkpG)