The cursus publicus — the postal service of the Roman Empire — being, together with the army, the main beneficiary and priority user of the Roman road, it used these stages for the rapid delivery of messages and news. The system worked so well that its vehicles could travel, under favorable conditions, up to 75 km per day (for comparison, the same service, in 1550, only covered a maximum of 45 km daily).
Security on these routes was relative. We very quickly saw the need to build forts and military camps near them, whose role in policing the Empire is undeniable. Some, like at Jublains in Roman Gaul, are veritable fortresses. Also, the garrison could be used for track repair.