From the Summary in Observations on marching Roman Legionaries ..
the Roman legionary probably carried no more than 40 kg of clothing, equipment, food, arms and armour;
a legionary in a typical campaigning day, marching on-road 29 km in approximately 7:30 h and building a temporary marching camp, probably expended between 5500 to 6000 kilocalories of energy, and required the same in replenishment;
the legionary would require between 9 and 11 litres of water to avoid dehydration and heat stress;
off-road marching required the expenditure of less energy than when using a road;
a typical legionary (body weight 80 kg, load weight 40 kg, march velocity 1.2741 m/s), could have marched along any of the roads in Britain for an energy expenditure of between of 501 to 542 watts;
Roman legionaries had an on-road march velocity in the range 1.2741 to 1.3411 m/s (2.85 to 3.0mph or 4.59kph to 4.83kph), with the lower value being more likely to have been the more common velocity;
at an on-road velocity of 1.274 m/s for 29 km, the last ranks of armies greater than 3 legions in size would have arrived after sunset, therefore, large Roman armies marched in multiple columns (August 11th daylight hours);
Roman legionaries were expected to march for 7 to 9:30 h each day – these times were not exceptional, did not overly tire the soldiers, and would have been sustainable, that is, the norm for either on- or off-road marching;
off-road velocities were probably in the range 0.6706 m/s (1.5 mph, 2.41 kph) to 0.7639 m/s (1.71 mph, 2.75 kph);
off-road, single column marching over 15 km or more, and for legion strengths greater than 2, was not a normal, sustainable option and requires other marching strategies;
all armies over 2 legions in size probably marched off-road in multiple columns to reach their destinations;
a) Roman armies of 1 and 2 legions in size could have marched in single column along a road; b) armies greater than 2, possibly 3, legions marched in multiple columns, whether on- or off-road.