Road construction technology and activities

Road construction technology

Road construction technology is the set of methods, materials, tools, equipment and procedures used to build a road from the survey stage to the finished pavement, so that the road meets the design standards of strength, durability, safety, economy and time. It covers the planning of operations, the choice between labour-based and equipment-based methods (in Nepal, labour-based methods are common for rural roads), and quality control as per the specifications (Nepal DoR "Standard Specifications for Road and Bridge Works", IRC and MoRTH).

Activities in road construction

The main activities in constructing a road are:

1. Survey and setting out - final location survey, fixing the centre line, bench marks, and clearing limits (right of way).
2. Site clearance - cutting trees, removing stumps, boulders and topsoil; demolition of structures.
3. Earthwork - excavation in cut, hauling and filling to form the formation level; compaction of embankment in layers (150-200 mm) to 95-97 percent of Proctor density; benching and slope trimming in hills (planned using the mass haul diagram).
4. Drainage and protection works - side drains, catch-water drains, cross-drainage (culverts, causeways), retaining/breast walls, bioengineering for slopes.
5. Subgrade preparation - scarifying, watering, compacting the top 500 mm of soil to specification and checking CBR.
6. Sub-base and base courses - granular sub-base (GSB), WBM/WMM or stabilised base; each layer spread, watered and rolled.
7. Surfacing - prime coat, tack coat, bituminous binder course (DBM/BM) and wearing course (BC, premix carpet, surface dressing, Otta seal), or a cement concrete pavement slab.
8. Shoulders and kerbs - construction of earth/gravel shoulders, kerbs and edge drains.
9. Road furniture and finishing - signs, markings, guard rails, kilometre posts, plantation.
10. Quality control and measurement - field tests, levels, thickness, density and payment measurement, following the Nepal DoR "Standard Specifications for Road and Bridge Works" and IRC/MoRTH specifications.