Design-Manual-for-Low-Volume-Roads-Part-G

G - Chapter 9 - 26
Development, if neglected:
Concentration of flood flow causing erosion and possible overtopping and
damage to roadway, paving or shoulders.
Maintenance Activity
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122 Ditch Clearing (Manual);
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230 Ditch clearing (Mechanised).
a) Manual Method (122)
This is a Regular Maintenance activity. The object is to remove all soil,
high vegetation, materials and objects from the ditch which could possibly
interfere with water flow or cause an eventual blockage of the ditch. This
can include for example, rocks, loose silt and sand, weeds, trees, bushes,
including their roots, etc. Dispose of these materials well away from the
roadside so that water flow will not be impeded and they will not fall or
wash back into the ditch. NO soil material or debris should be placed on
the roadway. On unlined ditches a short grass cover can help to stabilise the
bottom and sides of the ditch. Therefore where a side ditch is established to
the correct depth and profile with grass cover and no erosion, it is advisable
to merely cut the grass short. This will leave the roots in place to bind the
drain surface together.
At some locations it may be necessary to RESHAPE/REGRADE/DEEPEN the
ditch.
It is advisable to adopt a trapezoidal ditch shape when using labour
methods. The excavation using a hoe/mattock and shovel is easier than
for a V-shaped ditch. An added advantage is that the flat invert causes less
concentration of water than a V-ditch.
PART G: WEREDA ROAD MAINTENANCE BOOKLET