Reconnaissance survey information

Reconnaissance is a rapid field study of the alternative routes that were picked in the map study. The following information is collected.

1. Topography: general terrain, ridges, valleys, cross-slopes, possible gradients, mountain passes.
2. Streams and rivers: number and size of stream crossings, high flood level, river course, bed material, suitable bridge sites.
3. Soil: type of soil (clay, silt, sand, rock), suitability as subgrade, swamp or black cotton soil.
4. Geology: rock type, landslide zones, faults, unstable slopes.
5. Drainage conditions: water table, flooding, seasonal streams.
6. Land use: forests, farms, settlements, graveyards, religious sites, protected areas.
7. Construction materials: quarries, sand and aggregate sources, water and the lead distance.
8. Climate: rainfall, snow, fog, wind, temperature.
9. Existing roads and bridges, their conditions and possible use.
10. Cost of land and property, utilities (electric, telephone, pipes) to be shifted.
11. Labour and equipment availability, and accessibility to the site.
12. Social and environmental aspects, e.g. effect on local people.

Instruments used: Abney level, compass, tape, pocket altimeter, GPS and camera. The final output is a comparison of the routes with rough lengths and cost, from which 1-3 are selected for the preliminary survey.