Definition of "zonal"

Decisions made at the DfT inevitably reflect a London-centric experience, with a comparison being made with the closure of ticket offices throughout the London Underground network. This is not judged to have been detrimental, but there is a simple zonal fares system that is hardly comparable with the range of ticket types used on the national rail network.

2023 July 26, 'Industry Insider', “Ticket offices RIP?”, in RAIL, number 988, page 68