This variation is shown in various studies’-4. Demand for high quality transport service (such as e.g. express commuter buses or frequent rail transit, with public transport-oriented development) tends to increase with income until a medium to medium-high income is reached. Moreover, the demand for a high quality public transport service is potentially much greater in total than for a basic service. Furthermore, even if, as suggested in other studies', changes in income affect public transport demand either directly (positive impact) or indirectly through increased car ownership (negative impact), the indirect impact may be negligible for urban public transport. This is because car owners may still choose to use public transport for urban mobi lity instead of the car, or use both.