The types of cross sections commonly used on route surveys are shown in
Figure 26.2. In flat terrain the level section (a) is suitable. The three-level section
(b) is generally used where ordinary ground conditions prevail. Rough topography
may require a five-level section (c), or more practically an irregular section (d). A
transition section (e) and a side-hill section (f) occur when passing from cut to fill
and on side-hill locations. In Figure 26.1, transition sections occur at stations
and while a side-hill section exists at
Thewidth of base b, the finished roadway, is fixed by project requirements. As
shown in Figure 26.1, it is usually wider in cuts than on fills to provide for drainage
ditches. The side slope s [the horizontal dimension required for a unit vertical rise
11 + 21 11 + 64, 11 + 40.