Public transport is a system of multi-passenger vehicles that transport people along a pre-determined route. There are several different types of public transport system: road-based transport (buses, coaches and trams); railways (trains); underground urban transport (primarily the metro system and the RER); maritime and river transport (ocean liners, water shuttles, river boats and ferries); and airborne transport (primarily planes).
Increasingly, public transport systems operate in or on dedicated lanes, such as bus lanes, metro and RER lines, etc. The term "dedicated lane" is used to denote a public transport system that operates on a route (space) that is entirely dedicated to that form of transport.
Users of all types of public transport are required to possess a ticket in order to use the service (either a ticket or a subscription card for regular users).
As well as carrying passengers, public transport systems play an important environmental role, as they consume less energy and produce fewer emissions per passenger than individual modes of transport. Depending on the characteristics of the urban or rural area they serve, these systems also help to ease road traffic congestion. Public transport systems therefore offer a beneficial alternative for users, as well as for local or regional authorities, both in terms of logistics and transport.