Reconnaissance survey - Defecation and Objective.

The second stage of the survey for highway location is the reconnaissance to examine the general character of the area for deciding the most feasible routes for detailed studies.

Some of the details collected during reconnaissance are given below:

1) Valleys, ponds, lakes, marshy lands, hills, permanent structures and other obstructions along the route which are not available on the map.

2) Approximate values of the gradient, length of the gradient, and radius of curves of alternate alignment.

3) Number and type of cross drainage structure, maximum flood level and natural groundwater level along probable routes.

4) Soil type along the routes geological features.      

5) Sources of construction materials, water, and location of stone quarries.

The details to be collected during reconnaissance :

Upon completion, the reconnaissance survey should support the routes surveyed and provide a basis of study shouting the advantage and disadvantages of all routes reconnoitered. Typical data collected in a reconnaissance survey are-

- Sketches of all routes reconnoitered.

-Reports of feasible routes.

-Data on clearing and grubbing.

-The number of stream crossings involving bridge spans exceeding 20 feet or 6 meters.

-The approximate number of culverts and spans less than 20 feet or 6 meters.

-Descriptions and sizes of marsh areas and natural obstacles.

-Unusual grade and alignment problems encountered.

-Anticipated effects of landslides, melting snow, and rainfall.

-Soil conditions and stream and substrata conditions at proposed bridge sites.

-Discrepancies noted in maps or aerial photographs.

-Availability of local materials, equipment, transportation facilities, and labor.

-Photographs or sketches of reference points, control points, structure sites, terrain obstacles, and any unusual conditions.