What are those things?
Some of the commonly used devices in a project are listed below. For additional information on each devise please visit the DGLVR website.
HEADWALLS AND ENDWALLS –
A wall built at a pipe opening to support the road, protect the pipe, and guard against erosion. A wall at a pipe inlet is called a headwall. A wall at a pipe outlet is an endwall. Headwalls and endwalls support the road and protect the ends of the pipes from being crushed.
A structure under a road consisting of clean coarse rock wrapped in geotextile fabric through which water can pass freely. French mattresses are used in extremely wet areas, such as wetlands, to support the roadbed while allowing unrestricted water movement.
An underdrain is a drainage system installed under a road or road ditch to collect and transport subsurface water. These buried conduits come in a variety of shapes and sizes and are usually wrapped in geotextile fabric which allows water to enter the conduit while keeping sediment out.
A cross pipe is used as a traditional road drainage material. A cross pipe is placed at a certain angle and depth depending on the elevation of the road to drain water from a ditch line from one side of the road to the other, typically where water will have a good exit pathway. This helps with alleviating erosion problems within a ditch line.
DRIVING SURFACE AGGREGATE (DSA) –
Developed by Penn State’s Center for Dirt and Gravel Road Studies, DSA is a mixture of crushed stone developed specifically as a surface wearing course for unpaved roads. DSA has a unique particle size distribution designed to maximize packing density and produce a durable road surface that performs better than conventional aggregates.
Description/photo source: www.dirtandgravel.psu.edu