The big four railway companies operated their internal trains with their own coaches, presenting a unified image. There was variety under the surface however and many trains crossed the boundaries, being passed on to another company with just a change of engine. Through trains linked major cities, with the participating companies providing coaches or trains in proportion to the milage run on their tracks. Many connections were provided by through coaches, some trains were even formed entirely of portions from/to the other railway companies.

All of these coaches are Era 3 models. Details of the periods covered by the era numbers can be found here.