 4.531 metres, was transmitted to a mechanical counter in the coach by means of a chain.Zürner's assistants used a measuring cart in the shape of a wheelbarrow for those tracks unsuitable for a coach, which likewise measured the distances by the turning of a wheel and which was carried as the so-called "fifth wheel on the wagon" ("fünftes Rad am Wagen") in a case on the surveying coach.Both methods enabled a very accurate survey of roads.