In Britain trains usually keep to the left­hand track of a double line of railway, and it is this arrangement that is meant by the rule of the road. In some countries where there is very little double track any rule is of less significance since in almost all the countries surveyed there is no fixed rule about which track is used at passing loops on a single line route. In other countries reversible working is common and it may not be at all obvious which is the "normal" arrangement. Where the word "varies" appears under this heading, this situation is implied. Other countries with a well­established "rule" but having a certain amount of reversible working ("banalisation" is the French term for this) are distinguished by a note to that effect.

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