H0 scale (HO scale in North America, Japan, and Australia, and sometimes in Europe, including the UK) is the most popular scale of model railway in most of the English-speaking and non English-speaking world (in the United Kingdom, OO gauge—with trains built to a larger scale but using the same track as H0—predominates). In H0 scale, 3.5 mm (0.14 in) represents 1 real foot (304.8 mm); this ratio works out to about 1:87.086. In H0, rails are usually spaced 16.5 mm (0.650 in) apart which models the standard railroad gauge of 1,435 mm (4 ft 8½ in).
Construction of the HO scale model railroad display began in 1991. As with most model railroad displays, there is always more work to do. Per the National Model Railroad Association (NMRA) Kalmbach Memorial Library, the SLHRS has the largest HO scale helix in the United States both in height and in diameter.
There is over 4,000 feet of track on 3 levels, dozens of switches, and miles of wiring that have been installed by society members. It takes about 45 minutes for a train to travel the entire length of the display at scale speed. Most locomotives and rolling stock are membership owned and cared for.
The HO scale display represents the Southern Pacific Overland Route from here in San Leandro through a variety of cities along the way through to Reno/Sparks, Nevada. This route can be followed today by taking Amtrak from Oakland to the station in Reno. Of special note represented centrally in the display is the icing platform in Roseville that was used to supply the cars for the Pacific Fruit Express trains, the Alameda Mole, and the Snowsheds of Donner Pass and Emigrant Gap.