@ Halfinax, I agree. Not a few meters deep. A 200,000 pound atlas has a footprint that might be approximately be 36-40 square feet of area but I could be wrong. I drew up alot of 'Mechs to scale in AutoCAD years ago and might be getting some mixed up. (im being overkill here because the entire surface of the foot does not contact the ground. It likely has high-low points like a hiking boot and will have some kind of tread). High grade concrete with adequately compacted backfill today on terra should be able to withstand 6000 pounds per square inch, which equals with the worst case (worn foot?) 40 square feet of Atlas boot: A resistance of ~2,880,000 pounds. Based on its supposed weight, it should be putting something like 10,000 pounds per square foot of pressure down per slow, gentle, sneaky footfall. So that's 120,000 pounds per square inch.
Whoa an Atlas wouldn't dent it then! Not necessarily true. High grade concrete would be at the starport where dropships land. Ferrocrete is probably an order stronger even than our typical high-grade crete. More likely medium grade will be lining the city streets, since they still need to support the weight of construction 'mechs and other heavy utility vehicles. Medium grade is supposed to withstand somewhere around 4000 pounds per square inch which converts to a resistance per 40 sq-ft atlas boot of 1,920,000 pounds. See if you factor that the bottom surface area of the foot actually has more like 20 feet of square footage, or even a little less... that brings the resistance to nearly a million pounds per square inch.
While the math suggests you shouldnt have any footprints, many factors abound. It might be old and not at full-strength, there might be sand, dirt, stress fractures or decay, etc... there SHOULD be footprints. Because all the above numbers are based on the fact that we are gently setting the foot down. If he is stalking something, it might not leave a depression, but the math changes exponentially when you are slamming 200,000 pounds of death into the ground with inertia and a near jog. I don't know how to do that math exactly, but I am sure you might leave a depression of a few inches in either, but not much more than 6 inches or so by my reasoning. With all factors of concrete psi, initial construction, curing, etc... etc... the Atlas might be bringing down its foot at close to 30,000 lbs per square foot, but the concrete should still hold or just barely give.
As usual, feel free to correct me if I screwed up math class again.
SIDE NOTE!
I'm not sure we should consider persistent footprints despite the technology and capability to do so even on a low to medium grade computer. The reason is a possible tactical imbalance. Your team drops and their team drops. You aren't supposed to know what kind of 'Mechs they have until you spot a scout, or engage their other elements.. but if footprints are persistent, you not only know where they went, you should be able to tell what type of 'Mech it is based on the tread and footfall pattern. If you all tuned down radar (I dont recall reading whether this would be possible or not) and circled the city a few times, each team might stumble upon multiple treads and be able to determine the type of 'Mechs they are up against. I'll agree that would be a classic bait tactic but then a scout 'Mech is such a lightweight, based on the math upstairs, it might not make an impression even on medium grade crete.
Pro / Con. Footfalls can be a good thing! Is it realistic? Absolutely. Will the Devs consider it.. I dunno. It does need to be put on the table and tossed back and forth. I am sure persistent footfalls would challenge the current vision of gameplay and tactical balance even at this fairly early stage. To give those geniuses some credit, they might already have it ironed out and included, but it would be one of the tiny details that they might leave out and just surprise us with at launch/beta day.
My 2 cents.
Edited by TimberJon, 25 February 2012 - 12:52 AM.