The document discusses modal split and traffic assignment in transportation planning. It defines modal split as the process of separating trips by travel mode, usually expressed as a percentage of total trips. Traffic assignment involves allocating trips between zones to routes in the transportation network. Common traffic assignment methods include all-or-nothing assignment, which assigns all trips to the shortest route, and capacity restraint, which considers road capacity. The document provides examples of calculating modal split using a utility function and performing all-or-nothing traffic assignment on a sample network.