Arial photogram try induces the use of photographs taken in a systematic manner from the air they are then controlled by lend survey and measured by photogrametric techniques. Since the First World War the terrestrial photographic surveying has been replaced by aerial photographic surveying or aerial surveying for most of survey work due to development of aero plane.

It is the maximum pressure which may be applied to the soil such that the two fundamental requirements are satisfied Limiting the settlement to a tolerable amount. It is the net loading intensity at which neither the soil fails in shear nor there is excessive settlement which may be harmful for the structure preventing shear failure of soil.

The pre-stressing of concrete has several advantages as compared to traditional reinforced concrete (RC) without pre stressing. A fully prestressed concrete member is usually subjected to compression during service life. This rectifies several deficiencies of concrete. The following text broadly mentions the advantages of a pre-stressed concrete member with an

Verticals are taken with the axis of the camera pointing vertically downward. These photographs can produce more accurate maps as the variation n scale over the area is smaller and no area remains hidden. However the details in photograph can not be easily identified as the view offered is unfamiliar to eyes. Oblique are produced by giving a camera a tilt up to 30 to the

Aggregate is a granular material, such as sand, gravel, crushed stone, crushed hydraulic-cement concrete, or iron blast-furnace slag, used with a hydraulic cementing medium to produce either concrete or mortar. Those particles that are predominantly retained on the 4.75 mm (No. 4) sieve, are called coarse aggregates. Those particles passing the 9.5 mm (3/8 inch)