You know, you're kinda violating physics while saying that
1 tyca > 1 mile, but 1 TaPH < 1 MPH, as velocity = distance / time. For example, let's assume that you are driving 150 tycas for two hours and also 100 miles for two hours.
150 tycas > 100 miles
150 tycas / 2 hour = 75 TaPH
100 miles / 2 hour = 50 MPH
75 TaPH > 50 MPH
Otherwise, a great update, your roadgeekery-"skills" (idk how to put it :D) are magnificent and your cities are also very well done!