Worldbuilding Part 1: Travel and Time

Anyone who knows me should know that I love worldbuilding.  I've been bodging together the fantasy world Kallvor for the last thirty years and it's where pretty much all my games take place.  That's a long time and a lot of stuff has morphed and changed over the years as I define, refine, and redefine things.  This post kicks off another potentially-multi-part series, this one covering one of my favorite topics.  We start small but my hope is that somewhere in my column scribblings and random research someone finds some value.

Obviously, anything I say here is my own experience and opinions unless otherwise stated.  I don't have to say this stuff anymore but it's good to point it out now and again.

Before We Begin...

Some of my leanings should probably be enumerated before we get too far otherwise it'll sound like I think you should always do things the way I did.  You obviously don't--it's your world, do what you want.  

• I like low fantasy worlds where magic is rare and powerful but relatively weak compared to other fantasy worlds.
• Things should make sense where they, governed by predictable rules.  This goes for the peoples of the world as much as the other mechanics and the metaphysics.
• The corollary follows that we should draw from historical data wherever possible though note that history occasionally makes less sense than things we might make up ourselves.
• Try not to overbook too many things.  Yes, I have two and a half feline races and have broken my own rule.  It seriously could have been a lot more.
• Verisimilitude is important.  Explain away anything that otherwise doesn't make sense.
• Keep true to the source material wherever possible even when it's scattered, incomplete, or downright contradictory.  This will apply more to future posts than this one.  
• Mechanics should flow from the world wherever possible.  This is more for the game design crowd, but it's how I work with this stuff.
• Depth isn't important to all players, but it'll be suspiciously absent for those looking for it.  Build the history of things wherever possible.

How Big Is Your World?

"Big" in this case is really shorthand for "travel-able" because that's what's really pertinent.  We often see folks on Critical Role travelling huge distances or between planes with relative ease.  If you can go halfway across the known multiverse in the blink of an eye it implies quite a few things not limited to "distance is not an obstacle".  For instance, characters with access to boats in an island world have a lot more options than those without.  This is why Commander Shepard has the Normandy.  

Beyond where you can go, how fast can you move?  More importantly, how long does it take to get there?  We're going to focus on low fantasy worlds since that's what I like and know most about but there are obvious parallels in sci-fi settings.  So what are some basics of travel?  We'll assume ideal conditions for most of this (safety, roads, good weather, etc).  Here are details and I'm sure someone will correct me if I get 'em wrong (this is the Ineternet, after all):

• Humans are pretty good at endurance but not so great at speed.
• Human walking speed is right around 3 miles per hour.  
• In an 8 hour day you can get about 24 miles; not coincidentally, the size of hexes on my "world" map (really a continent map).
• Marathons run by modern people (mostly human) complete at right around 4.5 hours and a marathon is just over 22 miles.  Some maths (sorry) lead us to a speed of just under 6 miles per hour.
• In an 8 hour day at marathon speeds a human can get ~48 miles.
• Note that long distance runners (I know one) sometimes go a lot further.
• Army movement is a little more complicated than "a bunch of people walking in a group."  For one, they tend to carry a lot of gear for...armying...and stuff like that.
• An army can really only move at the speed of the slowest element.  This is usually the support train containing supplies, pack animals, and whatnot.  While you'd think that a cavalry-only column could get a lot further, this isn't really the case but more on that in a bit.
• Loaded oxen and mules might only move at 10 miles per day (mules apparently faster).  
• Peasants tend to not be the best pack animals.
• Horses are better at speed than endurance, at least compared to humans.
• Walking speed is right around 4 mph which is ~32 miles per 8 hour day.
• At a trot they can go 8-12 mph depending on the horse or 12-15 mph at a canter.  We might be tempted to multiply these by 8 to find out how far we can get but normal horses don't really work this way.  Working backwards from endurance horse riding records we see that the 100 mile challenges come in at something like 12-15 hours which implies sustained travel at speeds of around 8.3mph and 6.6mph.  For an 8 hour ride we end up with ~53-66 miles per day which is slightly ahead of where our marathon runners are.  Note that these are modern races with well conditioned and well bred modern horses.  The Pony Express over much longer distances with dedicated relay stations to swap horses didn't beat these speeds on average.  
• And if you're curious like me, at a full gallop a horse can go 25-35 mph but really can't do this for more than a few miles.  Think of a gallop as the horse version of a human sprint.  
• Wagons move rather like horses assuming that they're being pulled by horses and not, I dunno, griffons or manticores or something.
• Note that most of the time a wagon is going to be moving at walking speed (~32 miles per day) but it depends on the wagon.  A really light sports wagon might be closer to the endurance riding speeds; probably less than 50 miles per 8 hour day.
• I don't have any experience with horses so this was all news to me.
• All of this assumes movement on well-kept roads which is pretty much the best case.  Adjust accordingly for weather, terrain, and other conditions like sickness and foraging and whatnot.

Why does any of this matter?  Understanding travel times and distance covered is the same in writing/GMing as understanding latency in network programming and how time and distance relate for interstellar distances.  Knowing how long it takes to get from A to B with basic (read:  common) modes of transportation is tantamount to knowing how fast information can travel from A to B.  Assuming no palantir style communication or other type of magical intervention, this is how long it'll take for word of, say, a village burning down from reaching the lords the next city down.  This is a thing that we're rapidly being desensitized to (err...speed of communication, not village burnings) in our modern world of supercomputers in our pockets and Amazon next day shipping (that's mostly logistics, though).  Back to fantasy-land.

Given basic movement speeds, what kinds of structures need to be in place for things to function?  How close do villages have to be to their protecting lords to get a message that skorchers were on the way in time that the village isn't pillaged before defenders could arrive?  How much wealth can a lord generate based on the maximum density of villages he can protect?  How would we increase this in meaningful ways while still maintaining "enough" security?  A podunk village out in the middle of nowhere had better be a) so poor it's not a target, b) so hidden as to not draw attention, and/or c) so defensible that the inhabitants can deal with the majority of raiders that might get up in their grill.

Aside from our far-flung villages being mercilessly raided by bads, there are other practical concerns.  Where is the governing body of an empire?  Information moves incredibly slowly where travel isn't expedient meaning that revolts or invasions or something could be in full swing before anyone at the palace might hear about it.  What does this mean for its far-flung edges?  What about the length of military campaigns?  What about the length of military service?  What about trade?  Lots of forces fall out of thinking about the basics.  This is where verisimilitude lives--in the details that we often overlook but we'll dig into those more later.

[And for those of you wondering, this is day 9 of Shoe's 30 for 30]