There are very large model railways for the garden and very small ones for the table at home. Each size has its advantages and disadvantages, with space requirements competing with detail accuracy. The size often determines feasibility, including in terms of cost.
The track gauge describes the distance between the inner edges of the two rail heads of a track. Size 0 is therefore about half the size of size H0, which stands for half-zero.
The standard gauge in the Central European rail network is 1435 millimeters. This is probably the most widely used gauge worldwide and is often referred to as standard gauge. In addition, there are many narrow-gauge and industrial railways with different gauges.
In model railways, the flange sizes also sometimes differ. These are the bulges on the wheels that prevent a wagon from sliding out over the rail head. Models that are decades old may have higher flange heights, which make it difficult to run them on more recent model railway turnouts. For example, Märklin metal track from the 1960s, known as M track, is constructed differently from more modern track from the same or another model railway manufacturer.
The wheel flange keeps the wagon on the track. (Photo: Attenhauser) Anyone who wants to build a model railway must first decide on the desired track gauge. A large gauge requires more space. Those who don't want to depict everything have an advantage. A section instead of a huge station is also a lot of fun. Instead of a double-track line with a large city station and a sprawling industrial area, you can go a few sizes smaller. Experience shows that those who limit themselves to a smaller section are more likely to get started and enjoy tinkering and technology sooner. Standardized modules or custom segments can be expanded or exchanged as desired. This allows model builders to try out different eras and regions, give free rein to their imagination, and not have to adapt to the theme of one large, space-consuming layout. Incidentally, for those who string modules together, room doors are no longer an obstacle.
I am convinced that those who build a 50-centimeter-long and 30-centimeter-deep section are more likely to end up with a large layout than those who spend decades daydreaming and planning. It is better to start with a few small things, a locomotive, a few cars, and some track than to spend years studying track plan literature and waiting for the big thing to happen sometime in the distant future.
The table shows a scale comparison of common model railway sizes (designation, European scale, standard gauge):