Almost 80 miles round trip (125 km).
Depending on the route it could be 3 to 5 miles more.
It's almost flat, only a 150 HM's a day.
In summer I do it 3 times a week, in winter (it's usually just above freezing here, and lots of times wet) once a week.
My average is between 17 (winter) and 20 (summer) mph.
Before I got this job, I commuted for 8 years 21 miles a day, every day.