A new continuous forming machine that casts concrete pipe in a freshly cut trench at a rate of 8 to 12 feet a minute has been developed by a company in Arizona. The technique eliminates joints and seams, and is said to cut construction time and overall costs. Developed over the past nine years, the construction process consists mainly of a double-hoppered forming machine that is pulled along the rounded bottom of a ditch, while enveloping an inflated inner form. As concrete is discharged from the ready mix truck into the machine's double hopper, the forming machine is drawn forward by a cable on a winch. An electric motor on top of the machine operates the tamping devices that distribute concrete uniformly and tightly around the inner form. Although the first commercial installations have been limited to irrigation pipe lines, it is believed t the new pipe building process is not confined to this field. Work is in progress with the city of Phoenix on plans to lay storm sewers with the new system and to adapt it to the vast sanitary sewer and other concrete pipe markets.