9. Construction

The construction phase is the moment of truth for a road development. The best planning and design is useless unless it is incorporated into the finished product. Competent planning and supervision of the construction phase is probably the single most important factor leading to success. This requires a thorough knowledge of construction methods, equipment, materials, and testing coupled with a sense of diplomacy to communicate with the individuals doing the work. Such background will not only enable the construction supervisor to develop the road as planned, but will also allow him to effectively deal with the inevitable design changes required during construction because of unforeseen circumstances (especially in earthwork and drainage installations).

Some important erosion control practices to consider during construction include:

1. Keep slope stabilization work as current as possible with road construction.
2. A thorough job of cleaning and grubbing is required to insure proper construction of fills. Overcasting onto brush and timber or incorporating brush and timber into the fill material can lead to serious surface and mass erosion problems. In addition, provide a good base for fills and assure proper compaction as fills are constructed.
3. Where possible, the cleared vegetation should be spread evenly over the soil surface beneath the toe of the road fill. The vegetation material should be cut up or somehow crushed into the surface to assure close contact with the soil. This practice should enhance the buffering qualities of the slope beneath the road (see Table 2).
4. When installing culverts, avoid channel changes and place culverts so they conform to the natural stream channel as closely as possible. Remove as much debris from the channel above the culvert as possible. Carefully compact the fill material around all culverts to prevent seepage and ultimate culvert failure.
5. Keep stream disturbance to an absolute minimum and avoid it altogether during high flow periods.
6. Vagaries in weather conditions are important factors leading to erosion during construction. In areas where the climate permits, plan jobs for completion during dry periods. Elsewhere, limit the work area to small sections that can be completed before proceeding further. This exposes a minimum of disturbed area to erosion forces in the event of weather changes. Light rains usually have limited erosional impacts. However, if obvious impacts occur during larger storms, be prepared to cease operations after installing emergency drainage as needed. It is advisable to install all designed drainage from the downstream end of the job to the upstream end in areas of unpredictable weather.

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Last Modified: 07/05/2007