Paths should be built with a cross-fall or camber to shed water off the path. A cross-fall is normally used on paths which cross slopes, and a camber on paths on level ground.
On existing paths that are badly drained, the construction of a camber or cross-fall is the simplest method of improving drainage. This can be done to the path without the addition of any surfacing material. For short sections spades and shovels can be used, but on wide paths and for major improvement schemes a tractor with a grader, or an excavator is needed. Surfacing material simply laid on a poorly drained path will not make any long term improvement, as it will get trodden in and dispersed under waterlogged conditions.
On a path which crosses a slope, the cross-fall can either shed water straight down the slope, or into a side drain leading to a culvert. The choice depends on the general conditions listed below.
‘Lowland’. Porous soils, with surface run-off in streams. Removes flow from path only.
‘Upland’. Impervious soils, with surface run-off not in streams. Takes run-off from path and slope.
The best use of a camber is on wide paths on flat, poorly- drained ground, where it is necessary to raise the path, and to provide as much drainage as possible. A camber can be made using material from ditches dug on either side. Cambers are also usually made on forest tracks and rides, which are wide enough to make a functional camber that is comfortable to walk or drive on. Most footpaths are relatively narrow, and a camber steep enough to work is awkward to walk on.
The same profile of cross-fall or camber should be followed through any layers of surfacing.
Make the cross-fall about 1 in 40. For example, on a 2 metre width path, level using a block of wood 50mm high. Paths for cycles and wheelchairs should have a cross-fall of 1 in 50. The camber on a 2 metre width path should be 25mm, as shown. Wheelchair users generally prefer a camber to a cross-fall.
