Tyer's Electric Train Tablet

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Tyer's Electric Train Tablet system is a form of railway signalling for single line railways used in several countries; it was first devised in Great Britain by engineer Edward Tyer after the Thorpe rail accident of 1874, which left 21 people dead.^[1] It was used in New Zealand for close to 100 years until June 1994. The system used a hard disk called a tablet, a form of token.

The purpose of the system was to use the tablet as a physical guarantee to the traincrew that their train had exclusive right of way on the single-line section. Without it, they could not proceed beyond the section signal which protected entry to the next section of the single line.

With advances in electrical locking of the lever frame within the signal box, the tablet instrument also electrically locked the section signal lever. That was marked with a white stripe on the red background.