There are literally manuals about Highway Capacity..
https://sjnavarro.files.wordpress.co...tal_manual.pdf
You get 1900ish Veh/Lane/Hour... You add in friction for 90 degree turns at the bottom of a big hill in the mountains, a merge point, interchanges, that number comes down.
If you are then to reference OTIS:
http://dtdapps.coloradodot.info/otis/TrafficData
AADT is about 50,000 spread on 4 lanes (?)....
8-11 and 8-12 observe some math on k and d...
when you have a level of service of C or less (I think) and you have someone touch the brakes.... you then get a chain reaction reaching back in the platoon, you do have most drivers slow, and you also have interchanges there.