If a Human is in desperate need to run away from a monster and he decides to use three Move actions (Standard, Move, Action Point) on his turn to run, how fast is he running?
Assuming speed 6:
A square is 5'. Running gives him two extra squares of movement per move action, so he'll move 8 squares per action. He gets three actions in your scenario; thus, he's moved 24 squares. 24 squares is 120 feet.
A round is six seconds. Therefore, the human is moving 120 feet in six seconds, or 20 feet per second. That's 72,000 feet per hour, or about 13.6 miles per hour, although he can't sustain that speed for more than one round.
I've already done the math for this, so I just posted it in case anyone else was interested.
A few things need to be factored in, here. First, we need to establish the presumption that the Human in question is not using any equipment or feats that enhance or restrict his speed. Then, we have our first important value:
Human's Speed = 6 squares (PHB, p. 46)
Next, how many squares does the Human move in total? First, add two squares to his speed for Running (PHB, p.291), then multiply by the number of actions he's used to run.
Human's Running Speed = 6+2 = 8; Actions Used = 3; 3*8 = 24
Now that we know how far in squares he's run, we need to translate that to real-world metrics.
1 Square = 5 feet (PHB, p. 266); Squares Traveled = 24; 24*5 = 120 feet
The next question is, how long did it take the Human in question to travel that far? This will eventually lead to a measure of his real-world speed.
1 Round = 6 seconds (PHB, p. 26); 120 ft./6 s. = 20 ft./s.
Now, let's extrapolate that to a more common measure to give us something more easily recognized.
1 ft./s. = approx. 0.6818181818 MPH; 20 ft./s. = approx. 13.63636364 MPH
So, without any feat or equipment bonuses, a Human's top speed in D&D 4.0 is a little over 13 MPH.
Also, for those interested, here's a conversion rate I came up with that can be used for other calculations.
1 square per round = approx. 0.5681818182 MPH
I don't think you can count the AP speed boost outside of sprints.
World class sprinters are hitting 100m in under 10s
Using an AP ... running for 1.5 rounds (9s) so getting 3 actions in round 1 and 1 action in round 2, gives 32 squares = 160 ft = ~50m .... so pretty poor for a sprint
Middle distance runners are doing 1500m in 4 min
So 40 rounds x 2 actions / round + 1 AP = 81 actions x 8 sq / actions = 648 sq = 3240 ft = ~1000m .... again pretty slow.