chapter 2 (parts of a road)

crown

an established slope from centerline of a roadbed to the outside of the shoulders 1/4"- 1/2 "drop per foot of slope on pavement 1/2" - 3/4" drop per foot of slope on gravel or dirt allows water to run off from the centerline outward toward each ditch

surface course

area of the road vehicles travel on usually made of: asphalt (flexible pavement) concrete (rigid pavement) crushed stone

existing grade

elevation of the project site before any construction has been done driving surface of an existing road that is to be replaced

roadbed

is the width of the surface course to include both shoulders

base course

layer of compacted soil located between the surface course and the sub-grade

roadway

the entire width of the project including the ditches on both sides DITCH TO DITCH

travel way

the surface course that vehicles travel on

ditches

used for drainage "v" drainage ditch is usually used for unpaved roads flat bottom ditch is usually used for a permanent road with an asphalt or concrete surface

shoulders

ACT LIKE A RETAINER act as a retainer to hold in place each side of the surface course allows an area for emergency parking

sub-grade

MOST IMPORTANT FOUNDATION prepared base ready for placement of base course most important part of the road, if this fails the rest will break apart