Abstract :
NOT INFREQUENTLY bridges provide a means of crossing streams, highways, railroads, natural depressions, and so on, with power cables that is more economical than such alternates as submarine cable, tunnels, and underwater ductline. The number of circuits involved in the crossing usually determines whether the crossing will be an aerial cable or a conduit type of installation, and also provides a basis for determining the space and weight requirements which must be accommodated on an existing structure.
