Tunnel Warning Signals

Discussion in 'G / O / S Scale Model Trains' started by Malcolm G. Stewart, Mar 25, 2008.

  1. Malcolm G. Stewart

    Malcolm G. Stewart New Member

    A spur of the G-Scale, Digitrax DCC-RC, Penobscot & Pee Dee Railroad runs thru the Big Mountain via an 11' North/South-oriented tunnel. There isn't a set schedule; trains run in either direction as business dictates. Folks living in the North Village use the tunnel to visit friends in the South Village and vice versa. The P&PD RR cannot afford a full-time watchman for this infrequently used tunnel but, out of concern for the safety of the villagers, desires to install Dallee #557 beacons at the tunnel portals to flash warnings when a train approaches from either direction.

    The concept is that a sensor will be installed an appropriate distance from the tunnel portal which, when triggered by the passing engine, will initiate the beacons. [The "appropriate distance" being sufficiently long to allow a tunnel walker to exit before the train enters.] After the train exits the tunnel, the engine passes a similarly distanced sensor and the beacons will be shut down.

    Matters are straightforward for the Southern approach. This is a single track of sufficient length to accomodate placing the South sensor that "appropriate distance" away from the South portal. But things are not so easy for the Northern approach. An East/West main line runs close by the Northern portal and the track exits the tunnel into a right turnout (i.e., turns East) onto the East/West main line. There is not an "appropriate distance" between the North portal and the turnout. To provide the "appropriate distance" the North sensor must be located beyond the turnout, somewhere along the East leg of the main line.

    The above sensor placement will work as desired for tunnel traffic but any main line train proceeding in either direction along the East/West main line would falsely initiate the tunnel beacons--and they would remain operating indefinitely. To prevent this false alarm, the beacon circuitry must be conditioned by the status of the turnout: When it is open (i.e., routing traffic thru the tunnel), the beacon circuit is switched "on"; when it is closed (i.e., traffic moves along the main line), the beacon circuit is switched "off".

    [It follows from the above that, when the turnout is open, traffic cannot move Eastward on the West leg of the main line. And, when the turnout is closed, traffic cannot move Northward thru the South tunnel portal.]

    I have three questions concerning the above scenario:

    1. I would like to have a klaxon (or clanging bell, siren, what-have-you) incorporated into the beacon circuit. I've drawn blanks in my Googling; any suggestions?

    2. I haven't a clue as to what hardware is needed to sense and control the warning signals as outlined in the scenario. Recommendations, SVP!

    3. A sophisticated setup would also provide to give Red signals and/or effect dead track blocks for the two collision conditions [noted in the bracketed comment above]. Recommendations/suggestions, here?

    Thanks for your time and attention--and, hopefully, your comments.

    Malcolm Stewart
  2. kpolak

    kpolak Member

  3. Malcolm G. Stewart

    Malcolm G. Stewart New Member

    Thanks for the reference. However, I can't get any response when I seek it--can you provide a URL for the site?
    Thanks again,
  4. kpolak

    kpolak Member

    Just click on the underlined blue type, and it will open a new window for you, or z-stuff.net

    De nada

Share This Page