Line calculations for major road-lighting schemes

The paper employs a ladder-network method for calculating the voltages and currents at the lamp junctions in a major road-lighting scheme. The lighting circuit is dealt with in unit lengths of one mile, and, (partly to demonstrate the method), use is made of a step-up transformer at the supply point with simple chokes at the lamp positions. Only by the use of circuit theory can the minimal size of cable become known, and the paper suggests that an increase in the supply voltage might further assist in reducing the size and cost of the cable, at the same time giving the lamp designer greater scope in the development of more efficient lamps. Planning the lighting scheme in unit lengths would necessarily introduce a measure of standardisation, with resulting economy. Further economies might be made possible by the use of low-cost conductors in road-lighting circuits, and by the use of cheaper joints and looping techniques which such conductors could bring in their train. Consequent upon the enforced use of crash barriers, a simple procedure for laying cables on the centre reservation of motorways is put forward in the paper.