[23] It is, or was until recently, in some parts of India, the custom to omit the preparation of site plans, and to leave the fixing of the exact site of a work and the arrangement of ramps and other details to the judgment of the assistant engineer who was building it. Much unsightly work resulted. A chief engineer in the Punjab recently issued some orders on the subject.
For each kind of masonry work there is usually a type design. A few of its dimensions, which are fixed, are marked on it. The other dimensions are variable. It would be a great advantage to add to the design a tabular statement to show how these dimensions should vary under different circumstances.
Fig. 17.
Fig. 18.
13. Pitching.
The object of pitching upstream of bridges or regulators or downstream of bridges where there may be little or no scouring action, may be partly to protect the bank from damage by cattle or wear, or to prevent sandy sides from falling in. In such cases there may be pitching of the sides only, and it may be of brick on edge laid dry and under this one brick flat resting on rammed ballast ([Fig. 17]). Downstream of regulators or weirs and downstream of bridges if contracted or having piers which cause a rush of water, especially if the soil is soft, the side pitching may be as above, but with the bricks over one-sixth of the area placed on end and projecting for half their length. This “roughened pitching” tends somewhat to reduce the eddying. The bed protection should be solid concrete or blocks of concrete or masonry. Immediately downstream of regulators or weirs where there is great disturbance, both side and bed pitching may consist of solid concrete or of concrete or masonry blocks ([Fig. 18]).
Fig. 19.