Railway modelling is a hobby in which rail transport systems are modelled at a reduced scale, or ratio. The scale models include locomotives, rolling stock, streetcars, tracks, signalling, and roads, buildings, vehicles, model figures, lights, and features such as streams, hills and canyons.
The earliest model railways are the 'carpet railways' in the 1840s. Electric trains appeared around the turn of the 20th century. But these were crude likenesses. Model trains today are more realistic. Today modellers create model railway / railroad layouts, often recreating real locations and periods in history.
Involvement ranges from possession of a train set to spending hours and large sums on a large and exacting model of a railroad and the scenery through which it passes, called a "layout". Hobbyists, called "model railroaders" or "railway modellers", may maintain models large enough to ride. Modellers may collect model trains, building a landscape for the trains to pass through, or operate their own railroad in miniature.
Some older scale models reach high prices.
Layouts vary from a circle or oval of track to the realistic, real places are modelled to scale. One of the largest is in the Pendon Museum in Oxfordshire, UK, where an EM gauge (same 1:76.2 scale as 00 but with more accurate track gauge) model of the Vale of White Horse in the 1930s is under construction. The museum also houses one of the earliest scenic models - the Madder Valley layout built by John Ahern. This was built in the late 1930s to late 1950s and brought in realistic modelling, receiving coverage on both sides of the Atlantic in the magazines Model Railway News and Model Railroader. Bekonscot in Buckinghamshire is the oldest model village and includes a model railway, dating from the 1930s. The world's largest model railroad in H0 scale is the Miniatur Wunderland in Hamburg, Germany. The largest live steam layout, with 25 miles (40 km) of track is Train Mountain in Chiloquin, Oregon, U.S..
Model railroad clubs exist where enthusiasts meet. Clubs display models for the public. One specialist branch concentrates on larger scales and gauges, commonly using track gauges from 3.5 to 7.5 inches (89 to 191 mm). Models in these scales are usually hand-built and powered by live steam, or diesel-hydraulic, and the engines are often powerful enough to haul dozens of human passengers. Often railways of this size are called miniature railways. List of model railroad clubs.
The Tech Model Railroad Club (TMRC) at MIT in the 1950s pioneered automatic control of track-switching by using telephone relays.
The oldest society is The Model Railway Club (established 1910), near Kings Cross, London, UK. As well as building model railways, it has 5,000 books and periodicals. Similarly, The Historical Model Railway Society at Butterley, near Ripley, Derbyshire specialises in historical matters and has archives available to members and non-members.