A small pit is excavated at each end of the pipe that is being replaced, and a small section of the old pipe is broken out. The slightly smaller plastic pipe is inserted into the old pipe and pushed along the section to be replaced. Although the new plastic pipes are smaller, the smoother surface ensures the amount of water carried through the pipe is not reduced by an unacceptable amount. The technique is not suitable for all pipe materials.
This technique was used in Queens Street, Portsmouth (above) in order to minimise traffic disruption, and again in Eastney Road, Southsea (below). The excavator is pushing / pulling the blue plastic pipe into the open end of the old cast iron main.