New Delhi, July 17 -- The Centre has decided that all national highway projects costing over Rs.300 crore must use precast material-slabs of concrete that fit into each other-a government official said, in an attempt to improve the quality, speed, and efficiency of road projects.

These precast slabs can be made either in factories or near the highway in contrast to on-site construction, which is known to cause pollution, delays, and traffic problems especially in urban and built-up areas.

Pre-cast concrete is currently used in infrastructure like bridges and metro pillars. The project cost stipulation is aimed at ensuring that they will be used in bigger highway projects. Facilities to make pre-cast concretes will have to be set up by c...