The program allows you to designate military or civilian travel.
Anyway, according to records, normal delegations of government officials could indeed make 60 miles/day, but only under perfect conditions and only for a short while. Government officials normally travelled around 25 miles/day. Meanwhile, relay couriers, in emergencies, can travel about 150 miles/day. But, again, they are the exception.
As for the ability to govern the outlying areas, its worth noting that, for most of its history (say, until the 3rd century, when everything started to fall apart at the seams), the Roman government was very decentralized and relied upon local governments for almost all of the actually governing. It is difficult to compare to the Chinese Empire, where there was a much more centralized government.