Bus utilization compares the time spent in revenue-earning service to idle time. It expresses the number of buses in service as a percentage of the buses available for service.
Aim for 100% utilization
Bus utilization should be 100% unless there are reasons to keep one or more buses on stand-by. Reasons to be on stand-by might include surges in demand or to cover for breakdowns. Normally, however, in the event of a breakdown on a low-frequency route it’s possible to divert a bus from a high-frequency route to cover.
Even when a bus is in service, inefficient scheduling may lead to poor utilization. A bus may spend an excessive proportion of its time idle at terminals between journeys, or operating without passengers before commencing, or after completing, a revenue-earning journey.
Beware of fixed costs
When a bus is idle, it’s incurring fixed costs (depreciation, insurance, license fees, etc.), but not earning revenue to cover them. If it’s operating empty between its depot and the route terminus, it’s also incurring operating costs, which are not covered by revenue.
Poor utilization will result in low profitability, and may also result in inadequate service capacity unless there is an excessive number of vehicles.
Ideally, bus utilization should be maximized, with each vehicle spending as much time in revenue-earning service as possible.
However, a balance must be found between utilization and load factors. There is no point in operating buses on journeys where there is insufficient demand to cover the direct costs of the journey.