Extra trains are considered what in relation to regular trains?

Extra trains are considered inferior to regular trains. This classification is based on operational rules that prioritize regular scheduled service over any additional or temporary train services that may be added. Regular trains typically have established schedules, routes, and precedence in terms of operations and signaling.

In the context of the rail system, this means that if there are any conflicts in the use of tracks or other resources, regular trains will take precedence over extra trains. Extra trains, being additional services that may not be regularly scheduled, do not have the same guarantees and are generally given lower priority when it comes to operation and track usage. This hierarchy is vital for maintaining efficient and safe rail operations.

Other options like superior, equal, or competing do not accurately reflect this operational structure. Superior suggests a higher status, which does not apply here, while equal implies a parity that does not exist in this context. Competing would indicate a rivalry or direct competition between services, which is not the case with extra trains in relation to planned regular service.