This paper deals with the various types of partial prestressing which were mentioned in the First Report on Prestressed Concrete of the Institution, published in 1951. These are compared with the classification suggested by CEB-FIP. The permissible working stress, ultimate load and limit state designs are discussed. Service ability
under normal working load should be achieved without danger of collapse under the greatest probable excess loading. Prestressed concrete, with its variety of types, is
particularly suitable, and its behaviour under sustained fatigue and impact loading is described with special reference to micro and visible cracking in composite members. To illustrate this, a number of partially prestressed structures built by British Railways, Eastern Region, during the period 1949-63 are described together with their state when they were re-examined by the author in 1970. Partial prestressing in other countries is also covered.