Road space
It is sometimes difficult to visualise the size of the army and the various units of formations of which it was composed. This table might help. It is the officially defined length of road that a unit or formation would take up if it was on the march and laid out in the approved format.
| All distances are in miles (1 mile = 1.6 km) unless stated | |||
| Unit or formation | Fighting portion | 1st Line Transport | Transport and Ambulances |
| Division | 8 | 5 | 1.67 |
| Cavalry Division | 6 | 4.87 | 0.62 |
| Infantry Brigade | 1.5 | 0.75 | – |
| Infantry Battalion | 590 yards | 210 yards | – |
| Field Artillery Brigade | 1230 yards | 860 yards | – |
| RE Field Company | 400 yards | 90 yards | |
| Divisional Train | – | – | 1755 yards |
Imperial War Museum image Q1084. A column of motor lorries on the Contay-Amiens road in September 1916.
Road speed
Units and formations were constantly on the move in the rear areas behind the battlefield: new ones arriving; formations going into action; formations coming out of action and moving out for rest; formations being redeployed from one sector to another. Planning these movements by road and rail required much work and expertise, for not only did the road space taken up vary by type of unit, but they moved at different speeds. The table below shows the standard rate, but of course in practice the rate of movement would vary:
| 1 mile = 1.6 km; 1760 yards = 1 mile | |||
| Arm | Yards per minute | Minutes required to cover a mile | Miles covered per hour inclusive of rest halts |
| Infantry | 98 | 18 | 3 |
| Mounted – at the walk | 117 | 15 | 3.5 |
| Mounted – at the trot | 235 | 8 | 7 |
| Wheeled transport | 2.5 | ||
| Motor lorries | 6 | ||