Page 178 - RoadCem Manual - PCT BV
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SKEW CULVERTS
Water courses intercepting the road at an angle of skew less than 20 degrees can generally be accommodated by a culvert placed at right angles to the road centre line.
INLETS
To avoid silting, culvert inverts should be placed at a grade of not less than 1.25 % for pipes and 0.5 % for box culverts.
OUTLETS
The invert level at the outlet of a culvert should coincide with the ground level. At steep situations energy dispation structures should be provided to avoid erosion.
FOUNDATION
Ideally, culverts should be located on sound foundations such as rock. Soft, saturated and expansive clay soils may cause settlements or seasonal movements and should be stabilized with RoadCem.
Figure 6.16 Low level drift. Figure 6.17 Vented drift.
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