REGISTER

J. Rose BSc, C. Eng., FIRSE

M.L. Engineering (Plymouth) Limited

Ever since the earliest days of railways there has been a requirement to detect the presence of a vehicle on a railway track. The first such methods were based on the notorious time delay block - a practice which, quite justfiably achieved an unenviable reputation for being extremely dangerous. The invention of the electric telegraph and its application to railways permitted the adoption of the manual absolute block system.

Perhaps the most significant signalling development in the nineteenth century was the invention of the track circuit - most often accredited to an American, William Robinson in the 1870's. Robinson certainly foresaw its use as an essential element in an automatic block system and thus we can begin to see the development of the two basic branches of train detection (or track supervision as  it is now sometimes referred to) continuous and intermittent systems, see Fig. 1.

It is the purpose of this paper to examine the relative merits of various means of train detection for block systems and in particular to discuss the solution adopted on the North Island Main Trunk line.