<a href="https://en.wikipedia.org/wiki/Cab_signalling" class="extiw" title="w:Cab signalling">Cab Signal</a> used on <a href="https://en.wikipedia.org/wiki/Metro-North_Railroad" class="extiw" title="w:Metro-North Railroad">Metro-North</a>
<a href="//commons.wikimedia.org/wiki/User:Darienredsox" title="User:Darienredsox">Darienredsox</a>
CC BY-SA 3.0
<span class="int-own-work" lang="en">Own work</span>