oh - there's MY ETA and the ETA I give the company.. I didn't mention that. I never cut it that close when talking to dispatch. I take MY ETA and add 3 to 5 hours, depending on terrain and likely traffic conditions at the end points.
We use mostly interstates - but even then, I can't figure based on even 60mph average - that's what I'm governed at. I initially used 55mph, but that's over-optimistic going from Denver to the Bay area. It was much closer to 50. A run from the bay area to Upper OR on a US highway actually came out to a hair under 48mph average.
Hills, even small ones, kill me, if I have any kind of load at all.
On the other hand, the other day, I went from Billings MT to Casper WY and averaged just under 58. Of course, the load was only 15K pounds, and the hills are less steep.
Another thing I'm making notes on is what companies accept early arrivals. Some don't care, some have "windows", and some are #### particular about when you roll through the gate.
A database is a wonderful thing!