culvert design and installation

 CULVERT INSTALLATION
Culverts by definition  are drainage structures used  to convey flood waters along  the  road side drains.There are two main type of culvert depending on  location and type of  inlet,namely;access culvert and cross drain culvert.
Access culvert are  located parallel to the road center-line while as the cross culverts are installed perpendicular  to the road center-line.
Cross culvert mostly has a box type of inlet and usually sited at river gauge to convey water from  left-hand to right-hand side of the road of vice-versa.
For a standard road of 5.4 meter cross section a 9M DIA or 6 M DIA culverts are preferred.

STEPS OF ROAD BENCHING

      Since year 2000 , new road construction technology methods have been   adopted in Kenya  for example benching.  
Benching is a method applied whenever one intend to extend the carriage width  of road section covered by gravel.
It involve digging on both edge of carriage   to a depth equal to depth of the existing  gravel which in  kenya standard road  of  cross section 5.4 meters is 15 centimeters .The bench should be flat and length atleast equal to width of roller used for compaction.
Steps involved  are: