Percentage of Peak-only Buses
In every city there are fluctuations in demand during the working day. Demand is normally higher during the morning and evening, when people are traveling to and from work, than at other times.

However, the variations in demand between peak and off-peak periods varies considerably between one city and another, depending on factors such as levels of activity, the extent to which working and school starting and finishing times are staggered, and land use patterns.

Catering for peak demand is expensive since it requires some vehicles which are used for only a limited time each day; in most cases such vehicles are unable to earn sufficient revenue to cover their costs in full.

Some operators charge higher fares at peak periods, reflecting the higher level of demand, and lower elasticity of demand, at these times; depending on the extent of the difference between peak and off-peak fares, this may make a substantial contribution towards the cost of providing additional peak vehicles.

A small number of peak-only buses may be provided cost-effectively if maintenance schedules can be organized so that buses required for routine maintenance are serviced at off-peak times, and are available for a limited time at the peaks. Approximately 5% of the fleet may be made available for peak use in this way.

The percentage of peak-only vehicles in urban operations is typically between 10% and 20% although in some cities may be as high as 50%..

In many operations, particularly the more informal ones, the number of vehicles in service remains almost constant throughout the day, but buses spend much more time standing idle at off-peak times. This is the case where full load dispatching is practiced, with buses queuing at terminals for long periods before a full load has accumulated.