Traffic patterns in residential buildings, either private or publicly owned, usually resemble those of hotels. Peak traffic density usually occurs in the early morning, but peaks will vary both in time span and in intensity. The peak traffic value for use in planning, is suggested as 6 per cent of total building population. The acceptable service interval for residential buildings is a highly variable quantity and must be assessed on criteria relevant to each application. Thus it is difficult to give general guidance. However, it should not be overlooked that extended waiting due to low quality of service can antagonize and frustrate elevator users. This in turn can lead to unpleasant reaction and social problems. If there is a requirement for a residential elevator system to access public areas, service levels must be given special consideration. Elevator equipment must also be designed to suitable standards for such application. Often the planning criteria will be set by the principal, such as a housing association or local authority. Further, modern residential buildings also need multiple use elevators like stretcher, service cum goods elevator
