Foreword

Electric interlocking gives increased speed of operation and, due to the ease with which an extensive area can be handled by one man, effects substantial economies in operating costs. In the following pages is described the latest electric interlocking on the Great Western Railway at Bristol, supplied and installed by The General Railway Signal Company Ltd.

Since this is one of the most extensive installations of Electric Interlocking in the world, the engineering information contained in this bulletin should be of value to those interested in the latest methods of protecting and expediting the movement of traffic by rail. he East and West signal boxes and works at 400 volts 50 cycle A.C., this being transformed at the East and West boxes to 110 volt A.C. which is used for all signal circuits.

The point operating current is taken from the 120 volt 200 ampere hour batteries trickle charged from the A.C supply, a D.C. ring main being provided between the East and West boxes.