Show RAILROAD QUIZ what is known as a slide detector fence to prevent train accidents due to falling rocks or earth slides in hilly or mountainous regions e electrically I 1 e charged r wire fences are made to serve as detectors if a fallin falling 0 rock or an earth slide breaks one or more of the wires in the fence a relay is released and stop si signals nals are set up to halt a train approaching from either direction the rio grande railroad has constructed many such fences at selected points throughout its system |