The designation "On30" in model railroading refers to the SCALE of the model (O scale) and the GAUGE of the track (30" Narrow Gauge.) On30 train models have become popular within the last 10 years, due largely to the efforts of the train manufacturer, Bachmann, which has introduced a wide variety of reasonably priced, but high quality products in this line. The results are trains that are an excellent choice for use in any ceramic Christmas village, or for modeling the lesser railroads of farms, logging, small ports and industries. OK, now what does "On30" mean?


    The "O" part of the designation refers to O SCALE, which indicates a 1:48 scale reduction from real ("prototype") size. So if something is 48" long or tall in the real world, its O SCALE model is 1" (1:48 ratio) long or tall. 1:48 scale is also expressed as "1/4 inch equals 1 foot" so a 6 foot tall conductor would be 1 1/2 inches (6 x 1/4") tall in O scale. A 30 foot tall tree or a 30 foot long boxcar would be 7 1/2  inches (30 x 1/4") tall or long as the case may be. So that covers the "O" (scale) part of On30, now on to the "n30" (gauge) part.

    Gauge in railroading refers to the distance between the rails that the trains wheels roll on. In the real world the usual distance between these rails is 4' 8 1/2" or 56 1/2".  This gauge  has been used on all  major railroads and trolleys in the USA for over 125 years, so it has become the railroad "standard" gauge. For various reasons some railroads built track and rail equipment with a wider or narrower gauge. The "n30" designation indicates a narrow gauge with the rail 30" apart. Reducing 30" gauge track to O (1:48) scale puts the rails of On30 model track 0.625" apart. As it turns out, HO (1:87) scale track (standard gauge) has rails 0.649" apart. This very small difference (0.024") makes it easy and generally acceptable to operate On30 trains on widely available HO track. In fact Bachmann, the industry leader in On30 trains, provides "HO" track with all their On30 train sets. The ability to use existing HO track to operate On30 scale trains has been a major factor in the rising popularity of models in this scale. Just be aware that if you already have an established HO train layout, although the On30 trains will operate on the TRACK, your buildings, figures, and landscaping will be too small in relation to the On30 trains, and you will have serious clearance problems in tunnels, under bridges and any place where scenery is in close proximity to the track. This is because the On30 trains are quite a bit taller and wider than HO trains. Even though the wheels a similarly spaced ("gauged"), the locomotive and car bodies of On30 equipment extends over the rails and ties in terms of width. If your layout is not established beyond a table with track, you will be good to go running On30 trains on your HO track layout.

    As just established, On30 trains run on HO track, therefore On30 trains DO NOT operate on Lionel or other O/O27 gauge 3 rail track.  Conveniently, On30  trains are designed to run on the  same electrical systems  as HO trains which is a DC (direct current) system, or recently (and optionally) a DCC (Digital Command Control) system. Lionel and other O/O27 3 rail trains operate on an AC (alternating current)  electrical system. So do not use your Lionel transformer to run On30 trains! But ... Lionel O/O27 is based (often rather loosely) on O scale (1:48), just like On30, so all the buildings,  figures, and landscaping for Lionel (etc.) are suitable for use with On30.  It certainly would be reasonable (rather interesting actually) to operate Lionel O/O27 trains and On30 trains on separate track systems on the same layout. Hmmm.... gotta go now.... off to the train room... time to come up with a new track plan!