Exploration Movement Rates

How long would it really take to explore a dungeon or cave? I'm just talking moving through the place and roughly mapping the perimeter. Not included: Searching through chests, desks, libraries; looking for secret doors; disabling puzzles or traps; spelunking through tunnels; etc. It does presume at least being on the lookout for possibly dangerous animals or enemies. It's hard to say how you'd even be able to measure this.

Here's the best stab I can take at it so far: the U.S. National Park Service has a very nicely laid-out website for Mammoth Cave National Park in Kentucky. In particular, it details over a dozen different tours on the site, including specifics for duration, distance, and difficulty. From these we can compute the average speed on these cave tours:

Method: The first four columns above are transcribed from the NPS website; "difficulty level" is an enumeration I added for the different difficulty descriptors; and speed is calculated as expected. Side observations: The "Trog" tour is, perhaps ironically, for kids only. The "Violet City Lantern" tour uses only open-flame lanterns (no modern lights) so as to recreate the experience of exploring the caves -- and living in an underground tuberculosis hospital that was located there -- in the early 19th century. (This latter sounds like among the most interesting to me!)

Conclusions: The speeds on these tours range from a minimum of 0.2 mph to a maximum of 1.5 mph, with an average of 0.7 mph. There is effectively no correlation between difficulty level and speed (R² = 0.04). For example, the "Easy" difficulty tours include both the slowest and the fastest speeds. There is a statistically negligible trend for the more difficult tours to be a bit faster.

Can we use this as a metric to properly gauge dungeon exploration speeds? Obviously, the experiment lacks many things: They are all safely pre-mapped routes, no one is in fear of being attacked, they're being led by knowledgeable guides, etc. On the other hand: The tours all have to account for civilians in all kinds of shape, they are organizing fairly large groups, the guides are stopping for discussions and questions, they're being environmentally careful (unlike tomb-robbing adventurers), they go up-and-down through rugged cave areas (whereas dungeons are mostly level constructions), etc. I'm sure the data is biased one way or the other, but I can't tell which.

Let's look at the exploratory move rates in OD&D. First, recall that standard human walking/marching speed is around 3 mph (from whence we get the "league" unit). OD&D sets basic encumbrance levels and move rates on Vol-1, p. 15 (and these are basically copied from Chainmail), with the exploratory turn movement in Vol-3, p. 8. This latter is described as "ten minutes to move about two moves -- 120 feet for a fully armored character". In summary we get this:

So that's pretty slow; only about 1/4 mile per hour for unburdened men; or, approximately equal to the slowest (and easiest) tour at Mammoth Cave Park. Of course, AD&D reduced the rate even further, dictating not "two moves" but only a single move of 10' per inch in a 10-minute exploration turn -- that is, half again slower than the numbers in the table above (1/8 mph at the maximum). The OD&D rate is slow, while the AD&D rate is very slow.

So today I'm thinking that those movement rates are probably too slow. Consider the following: These days I'm in the habit of using half-hour exploratory "turns". That seems like about the right pace for wandering monster checks, and it's also scaled to the approximate number of encounters per game session (e.g., many tournament writing guides suggest planning on about 7 encounters in a 4-hour game slot, plus time for setup; and in my experience this is roughly accurate). If we set exploratory movement conservatively below the average Mammoth Park tour speed, at say 1/2 mph, then this conveniently converts to nearly MV (in inches) × 100 feet per half-hour. This proposed rate is shown below:

Obviously, that's roughly double the exploratory move rate given in OD&D Vol-3 (and 4 times the rate seen in AD&D). On the other hand, it's half the underworld tunnel move rate specified in module D1-3, on the order of 1 mph  (one mile per MV per day, that is, 12 miles in a day for a person with 12" move). This seems possibly about right. It also seems roughly to scale with what my players cover in real gaming time when exploring and mapping, which I like as a usable rule-of-thumb. Of course, extensive area searches, fighting encounters, etc., add to this simple movement figure. Movement through previously mapped/cleared areas can be at a rate of 5 times this (as in AD&D PHB), so around 2.5 mph, a bit less than normal walking speed.

Can you think of any better way to model dungeon exploration move rates with real-world experimental data?