If the supply of the transport is less than the passenger demand the passengers are obligated to wait for the transport service for a long period of time which resulted in delay. Delays are the result of a great difference between demand for a service and the capacity available to meet that demand. Usually this failure to correspond is temporary and due to natural liable to vary in the timing of demands and in the duration of time needed to provide service. This delay, in turn, is resulted in the creation of the passenger queue. According to (The federal democratic republic of Ethiopia Ministry of transport, 2011) as the world population increases, life requires competition which needs increased mobility. Ability of moving from place to place with comfort, reasonable cost and desired time is one of the major factors affecting the competency of individuals. Human beings use different modes of transport for mobility. The growth of modes of transport varies based on the level of development of countries.
As Ethiopia is a developing country, the transport service accessibility is low. According to (Tilahun Meshesha Fenta, 2014,) the increase of population of Addis Ababa is a mixture of three basic processes: rural-urban migration; natural increase, and re-classification of land from rural to urban categories. This population growth leads to the change to another social group of the residents and consequently the demand for public transport for the movement. Compared to the developed countries the change to another social group rate and service standard observed in the city of Addis Ababa is low. In the cities of developed countries average mobility rate per person or trip/day is 2.5. According to (The federal democratic republic of Ethiopia Ministry of transport, 2005) transport study the Addis Ababa mobility rate or average trip/day/person is 1.08. Old neighborhoods far from the main roads and expansion areas of the city are not well served by public transport. The city’s growth in economy, geographical area and population, brings urgent attention and needs additional mass transport service provision supported by capacity and technology.