Roller supports are free to rotate and translate along the surface upon which the roller rests. The surface may be horizontal, vertical or slopped at any angle. Roller supports are commonly located at one end of long bridges in the form of bearing pads. This support allows bridge structure to expand and contract with temperature changes and without this expansion the forces

The irrigation system in Pakistan has brought great benefits to many people. Dependence on the natural hydrological system has been minimized and new settlements in canal irrigated areas have been established. However, the canal system has been accompanied by problems, which are increasingly difficult to overcome. Water logging and salinity are two of

A mixture of soil particles ranging in size from coarse to fine. Processing involve crushing oversized particles and screening where it is necessary to secure the desired grading. The requirements of a satisfactory soil aggregate surface are; Stability, Resistance to abrasion, Resistance to penetration of water, Capillary properties to replace moisture lost by surface evaporation

Land use pressures are particularly mounting on the edges of the urban areas; much of the land resources and capital lies in private hands. This puts a heavy responsibility on public bodies to maintain the balance between urban development and conservation needs. Urban planners do not seem to realize that class I and class II agricultural soils are a scarce and

Excessive size both in population and geographical area 
 Where the economic base of the cities is inadequate to cope with problems created by excessive size Tremendous amount of land being gobbled up by sprawl of cites, especially giant conurbation. The loss of agriculture land to urban/industrial sprawl is of grave concern. Once loss this prime land cannot be replaced.