The planning aspects of transportation engineering relate to urban planning, and involve technical forecasting decisions and more difficult political factors. Technical forecasting or urban passenger travel presently involves what is called the four-step urban transportation planning model, requiring the estimation of trip generation (how many trips for what purpose), trip distribution (destination choice, where are you going), mode choice (what mode is being taken), and route choice (which streets, transit routes are being used).
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 pavement, designing the geometry (vertical and horizontal alignment) of the roadway (or track).
Operations and management involve traffic engineering, so that vehicles move smoothly on the road or track. Older techniques include signs, signals, and markings. Newer technologies involve Intelligent Transportation Systems, including Advanced Traveler Information Systems, such as variable message signs, and Advanced Traffic Control Systems, such as ramp meters. Human factors are an important aspect of transport engineering, particularly concerning driver-vehicle interface and user interface of road signs, signals, and markings.