Networked Digital Key Token System


Key Token Signalling for the 21st Century for use on single OR double line working.


Please note that Critical Infrastructure Engineering Ltd no longer manufactures the Ternkey system.

The inventor and owner of the intellectual property has now retired.

If any organisation or individual wishes to acquire the Ternkey system then enquiries should be made via gt@gtaylor.co.uk


This patented Key Token signalling system networks specially designed solenoid-controlled, trapped-key locks. 

Instead of multiple keys controlled by just one lock - as in conventional token machines - Ternkey machines control single keys in multiple locks. 

The state of every lock in every machine is known by a central control unit. A set of rules for the whole railway  enables keys to be trapped or released to allow safe, flexible and efficient train running. 

It really is that simple!

For a full technical explanation, click here or go to the 'press cuttings' tab opposite and open the paper that was accepted as a reserve for ASPECT, the IRSE International Conference in Utrecht in 2019.

*** Click below for a video of the basic Ternkey sequence using some very basic units:


To collaborate in the Ternkey project or to use/acquire the patent, please go to the 'Contact' page.

Site reviewed/updated 20/09/23



© Critical Infrastructure Engineering Ltd. 2023     Company number  05297363

Patent GB2523100

Grahame Taylor - Director