Transportation engineering is a sub-discipline of civil engineering which deals with the application of technology and scientific principles to the planning, functional design, operation and management of facilities for any mode of transportation in order to provide the safe, rapid, comfortable, convenient, economical, and environmentally compatible movement of people and goods (transport).The planning aspects of transport engineering relate to urban planning, and involve technical forecasting decisions and political factors. Transportation engineering, primarily involves planning, design, construction, maintenance, and operation of transportation facilities. The facilities support air, highway, railroad, pipeline, water, and even space transportation. The design aspects of transportation engineering include the sizing of transportation facilities (how many lanes or how much capacity the facility has), determining the materials and thickness used in designing the geometry (vertical and horizontal alignment) of the roadway (or track).