Example of signal operations for rail transit
<div style="display:inline-block;padding:0 3px;background-color:#BDC"><a href="//commons.wikimedia.org/wiki/File:Rail_signal.png" title="File:Rail signal.png"><b>Original: </b></a></div> <div style="display:inline-block;padding:3px 0;"><a href="//commons.wikimedia.org/w/index.php?title=User:MHickman&amp;action=edit&amp;redlink=1" class="new" title="User:MHickman (page does not exist)">MHickman</a></div> <div style="display:inline-block;padding:0 3px;background-color:#CCF">Vector: </div> <div style="display:inline-block;"><b>Vectorization: </b> <a href="//commons.wikimedia.org/wiki/User:Sushant_savla" title="User:Sushant savla">Sushant savla</a></div>
CC BY-SA 3.0
<a href="//commons.wikimedia.org/wiki/File:Rail_signal.png" title="File:Rail signal.png">File:Rail signal.png</a>