Table 4-2. Ditch sections (continued)
Some of the factors in determining ditch shape are discussed below.
TRIANGULAR OR V
The triangular or V-shaped ditch is good for flows of less than 60 cfs. *Suggested side slopes of 3:1 allow
vehicles to get out of the ditch easily and prevent accidents related to overturned vehicles.
TRAPEZOIDAL
The trapezoidal ditch is good for flows larger than 60 cfs. *Suggested side slopes of 1:1 are sufficient where there
is no possibility of the ditch being a vehicle hazard.
*NOTE: The 60 cfs limit between triangular and trapezoidal ditches should be used only as a guide. The type of
ditch that is used will also depend on the equipment available to construct the ditch. For example, if scrapers are
not available, then the construction of a trapezoidal ditch may be much more difficult than a large triangular ditch
cut with a grader.
EN5465
4-8
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