If a government decides to provide public transport free at the point of use for all citizens, then:
the demand for public transport will be perfectly inelastic
public transport will become a non-rival good
some form of rationing will have to be used in the allocation of public transport
there will be no opportunity cost involved in the provision of the transport service
53 exam-style questions on OCR A Level Economics The economic problem. Each one has a worked solution and a mark scheme showing where the marks go.