Depends on where you are. On I5 it is 70 miles an hour. On most freeways it is 65 except when approaching a city and it drops to 55. In towns/cities it ranges from 35 to 40 except in school zones and...
From Califonia DMV: The maximum speed limit on most California highways is 65 mph. You may drive 70 mph where posted. Unless otherwise posted, the maximum speed limit is 55 mph on two-lane undivided...
Coax cable is OK for R.F. up to several gigahertz, over medium to short runs. For data, we went to twisted-pair with 100 megabit Ethernet, and twisted-pair is now used in 10 gigabit Ethernet. So......