The question is not whether public transport has a cost
Buses, trains and subways continue to require workers, energy, maintenance, fleet and infrastructure. The Zero Tariff transfers the passenger's payment directly to the public budget, specific contributions or other collective sources.
In Rio, the municipal system already combines fare revenue with a per-kilometer subsidy. This provides a starting point for estimating how much each source finances and what fare revenue would need to be replaced under a zero-fare policy.
What the estimate should include
A serious estimate cannot just multiply current passengers by the fare. Demand tends to grow, and supply needs to follow. There are also current free services, transfers, and differences between municipal and state modes.
- Tariff revenue actually collected, not counting internal transfers twice.
- Subsidy and other existing public expenses.
- Cost of expanding the fleet and trips to meet new demand.
- Renovation, terminals, accessibility, information and supervision.
- Reserve for variation in costs and contractual quality.
Who could finance
National and academic debates analyze the general budget, employer contributions, vehicle charges, parking, real estate appreciation and metropolitan funds. Each source distributes costs differently and requires a legal basis and governance.
In the case of Rio, it is still necessary to define whether the policy would only cover municipal transport or also subway, train, ferries and intercity buses. Without metropolitan coordination, free services may end at the administrative border.