@Edward T - 1.) Where have you been? Missed your "unique' posting & mostly informative posts. Trust all is well with you and your dog.
2.) Just a little tweek to your post- the average walking speed of people is 3.5 mph. Worked in product development of A-C class III products in the 70's and later with other companies (like Raymond) in the development and private label agreement of Mitsubishi Class III, low lift, walk behind, battery powered trucks. You will find that the top travel speed of just about every manufacture these units have a make speed of 3.5-3.6 mph when empty - ~ 2.9 with load.

Just a side note I walk every other day & have since 2007 on an indoor track (part of my program to get at least 10K steps in every day) and my averaging walking speed is 3.1 mph over a continuous 45 minute walk (fast paced for me & most other folks on the same track -some blue haired people there with me). Plus, I don't have long legs and when some one asks me "whatcha' up to", my pat answer is 5' 7" and stopped. That is a good thing as it means I'm not shrinking yet. With 7 decades, 1 year & 21 days on this planet that ain't too bad.

Now when I actually worked & received a pay check for a living - there were some people that really walked fast once a day. They were labeled members of the 501 Club and you better get out of their way when the clock says 5:01 PM - they probably were going 5.5mph+. They are easy to identify as they are most always just sitting at their work stations around 8:01 AM to 8:15 AM & booting up their computer.