Road maintenance; gully control measures

Road maintenance

Highway maintenance is the work done to keep a road, with its pavement, shoulders, drainage, structures and furniture, in a safe and serviceable condition and to preserve the investment, without changing the original design standard.

Classification (Nepal DoR practice and IRC:82):

1. Routine maintenance - small, regular, yearly works such as patching potholes, cleaning drains and culverts, clearing slips, cutting grass, and repairing shoulders and signs.
2. Recurrent maintenance - works repeated at intervals within a year or two, such as resealing cracks, re-gravelling shoulders and repairing drains.
3. Periodic maintenance - works at intervals of several years (3 to 8), such as resealing, regravelling, surface dressing and thin overlays to restore the surface.
4. Urgent (emergency) maintenance - immediate works to reopen the road after landslides, floods or accidents.

Measures for gully control

Gully erosion is the cutting of deep channels in road slopes, embankments, shoulders and the surrounding land by concentrated runoff. It is serious on hill roads in Nepal, where steep slopes and heavy monsoon rain produce rapid surface flow.

Measures for gully control

1. Diversion - catch-water drains above cut slopes, and side drains and cross drains/culverts at close spacing, to stop flow from collecting; discharge onto stable ground or into natural streams.
2. Lined drains and chutes - stone masonry, concrete or gabion lining for steep drains; stepped channels or drop structures to reduce velocity.
3. Check dams - small stone masonry, gabion or log dams across the gully at intervals to trap sediment and reduce the slope and velocity.
4. Outlet protection - aprons and energy dissipators at culvert outlets and drain ends.
5. Bioengineering - grasses (vetiver, broom grass), bamboo, shrubs and trees planted on slopes; brush layering and fascines (live check dams).
6. Slope treatment - reshape the gully, fill and compact it, terrace the slopes, and use mulching and geotextile or jute mats to hold the topsoil until vegetation grows.
7. Retaining and breast walls at the toe of unstable slopes.
8. Maintenance - keep drains clean and repair erosion early.