Light railways are non-public railways for transporting goods. Decades ago, they were used widely in quarries and other resource exploitation areas. Forest railways existed in large numbers, too, for transporting trees and logs out of hardly accessible forest terrain.
The light railway tracks were usually assembled from premounted track pieces - just like »king size« model railways. The track widths (500, 600 or 750 mm) were »toylike« compared to the normal gauge of 1435 mm. A solid foundation was neither necessary nor common: Varying destinations caused continuous rearrangements of the track layouts. But the low velocities of the trains did not call for high precision in track geometry anyway...
The rolling stock was produced by several manufacturers for sale »by catalogue«. In Germany, famous companies like Gmeinder, Deutz, O&K (Orenstein und Koppel), Diema, Demag and others delivered thousands of the small steam-, diesel-, electrically or compressed-air-driven locomotives to small and large firms. Cars existed for many purposes, ranging from dump cars to specialized tree transporters. Most equipment producers didn't survive until today, only very few are still active in this virtually extinct business.
The last of the many light railways are to be found in areas which are unreachable by heavier trucks and lorries, like moory landscapes or sandy coast areas. Also, mineral or metal mines deap within the earth still offer a »natural reservation« the tiny and flexible small railways. Some companies with large factory grounds do use the reliable and sturdy light trains even today. Several narrow gauge railways survived in scenic areas, transporting happy tourists now instead of raw materials...