what trains do you make controllers for

Question: what trains do you make controllers for
- Keywords:
  build,
  controller,
  make,
  research,
  train
Asked by 11crawatr1 to Andy on 16 Mar 2012.
- Andrew Hearn answered on 16 Mar 2012:
  
  Underground trains – there was one which was like the trains on the Docklands Light Rail. They’re controllers to detect different signals alone the line so that the train “knows” where it is, and when they should start stopping, that kind of thing.

Question: what trains do you make controllers for