In full size rolling stock, standard gauge is designated as 4 feet, 8 inches and was created by George Stephenson as he designed the Stockton & Darlington Railway. The size of gauge was determined by the width of the rolling stock used at the Killingworth Colliery that was served by the railway. In 1838, Isambard Brunel created a larger gauge railway of 7 feet, 2 inches, allowing larger, faster locomotives to operate on the London-to-Bristol railway more safely than large locomotives traveling on standard gauge lines.
The layout for large, fast moving express trains requires a track design with long areas of straight track allowing high-speed trains to move quickly along the track. For high-speed trains with long carriages, the bends that are included in a track layout should be long, winding turns that allow the train to take the turn at high speed without derailing. Slower moving trains, such as those with wagons, do not require as many straight lengths of track that allow high speeds to be reached. Track design for slower moving trains can include changes in height for hills and valleys, and sharper bends, according to New Railway Modelers. The use of model railways has different gauges, with O and O-27 gauge trains and lines being interchangeable.
The design of a layout for a larger scale model railways on any gauge requires the designer to consider the size and width of the rolling stock traveling on the line no matter what gauge of track is used. A track should be designed to ensure there are no blockages that could hinder the movement of the rolling stock; the dimensions of the rolling stock is known as loading gauge. Using the tallest and widest rolling stock, the layout should be created to allow easy movement of the loading gauge around the track.
When a track is designed with a turnaround loop at the end of a line, the payout must include points allowing the charge running through the line to be reversed. One side of the line runs a positive charge and the other is powered with a negative charge. As the loop turns, the negative and positive sides will overlap as the loading gauge returns to the line, and a small area of the line can be isolated, allowing the train to continue on the line.
