Transverse drains are similar in construction to lateral drains, except that they run perpendicular or slightly skewed to the centreline of the carriageway (Kasibati & Kolkman, 2006). They are mostly used to drain water that may infiltrate into the road bases and sub-bases at joints, see Fig. 13.18 (FHWA, 1980).
It is important to provide drains at joints in rigid pavements as the joints’ sealing can deteriorate with time allowing water to flow into the pavement. Perforated pipes are usually used as transverse drains and they may empty directly into the side ditches. Pipes as transverse drains are classified as passive drains, meaning that they do not constrain the water movement but they are placed in the hope that water will find its way into the drain. However, some of the water may move past the drain and cause some problems. Transverse drains should be used with caution in frost heave prone areas as differential frost action may damage the pavement structure.
Outlet Pip*
Coarae Filter Perforated Collector Pipe
—^Traneveree ‘ Interceptor Drain tatlet Pipe
■ Longitudinal Collector Pipe
Legend
Traneveree Draine on Superelevated Curve (16)
