The Impact of Terrain
The terrain we travel over impacts our speed and even reliability. Sand will impact a two-legged species less than a wagon, with wheels that are bogged down, but remember, from Chapter 4, that most deserts are rocky rather than sandy. A forest with thick underbrush slows everything. A light forest will have less impact. The density of underbrush in a forest is a moot point if there’s a cleared road through it. Rolling hills, foothills, and mountains will slow everyone whether there’s a road or not; it takes time to go up and down and this is worse on the legs of humanoids or animals, increasing fatigue.
Roads paved with cobblestones aren’t very smooth and can not only slow travel but fatigue feet and even wagons, where the bumpy ride strains construction. Such roads are more common near a city, extending only a short distance from the walls. Very dry, hard ground is tough on feet, which is why horses will prefer the grass. An unpaved roads means potholes and potentially mud.
Paving, when present, seldom extends far from a settlement due to expense. This is one way to indicate wealth, such as in an empire. We may want to decide that most roads are unpaved for most of their length.
Rivers can require traveling to a known crossing, which might be guarded by creatures or species who charge a toll or simply won’t let others pass without a fight. Given fords’ importance, such a crossing might be controlled by a city, sovereign power, or band of opportunistic thugs. But our main concern is to decide where a river crossing is between two settlements and measure the distance to it from both places, unless the bridge happens to be directly between them.
The Impact of Life
Wild animals and sinister species make traveling more perilous. On a wide open plain with low grass, one could see trouble coming from a long way off, but tall grass or a thick forest could slow our travelers even if there’s a road through the terrain. Due to this, there’s a difference between the theoretical travel time and the actual. This is another way to slow our characters.