| Model train enthusiasts have many different | | | | provides the right balance between the detail of larger |
| preferences and requirements. Some like trains that | | | | scales and the lower space requirements of smaller |
| run through the garden, back yard, or park. Others | | | | scales. |
| may have plenty of indoor space that can handle a | | | | HO model trains, which first appeared in the UK during |
| major train layout. Still others might have less space, | | | | the 1930s, were introduced as an alternative to the |
| but still want it to accommodate a complete setup. | | | | then standard OO scale. But OO scale was already |
| Model train makers seek to meet these needs by | | | | well established and therefore the HO scale had a |
| offering model trains in several sizes, or scales. | | | | hard time competing. Luckily, hobbyists in the United |
| Of the large-scale trains, the most popular size is O. | | | | States during the late 1950s were demanding more |
| The scale for O is 1:48, meaning that it is one-48th the | | | | realistic toys. This high demand allowed the HO scale |
| size of an actual real-world train. The gauge for O (the | | | | model trains to succeed throughout the 1960s and their |
| width of the track, between the rails) is 1 1/4 inch. | | | | popularity continues right up to the present time. More |
| HO - continental Europe's and North America's most | | | | than two-thirds of train lovers prefer HO to other |
| popular model railway scale - is half the size of the | | | | scales. |
| larger O scale (HO stands for "half of O"). The HO | | | | Due to the growing popularity of the HO scale, many |
| scale is 1:87. | | | | companies produce a great array of locomotives, sets, |
| In the UK, OO scale is the most popular. In this case, | | | | accessories, and rolling stock. As of 2008, |
| trains are built to a larger scale than HO, but they still | | | | approximately 70 significant manufacturers and |
| use HO gauge track (16.5 mm or 0.65 inch). | | | | marketers of HO railroad equipment were active. Train |
| HO scale is popular because it is small enough to allow | | | | enthusiasts can find HO scale train sets with |
| the creative use of scenery without sacrificing too | | | | ready-to-run trains and modular track, high quality kits, |
| much space. But it is also large enough to allow a | | | | supplies for scratch-building, and even limited-edition |
| great amount of detail in locomotives, rolling stock, and | | | | locomotive models. |
| accessories. HO train cars and landscape elements | | | | Today's HO trains run on two-rail track, powered by |
| are big enough for children to handle without much risk | | | | direct current or by Digital Command Control. Some |
| of small parts or tiny components being swallowed by | | | | trains, notably those of Germany's Maerklin, run on |
| accident. For many model railroaders, the HO scale | | | | alternating current. |