What specific traffic study finds out where people start their trips and where they are headed?

The specific traffic study that finds out where people start their trips and where they are headed is called an Origin-Destination (O-D) study, also known as an O-D survey. This study systematically collects data to understand the flow of people and goods from their starting points to their ending points. An 'origin' refers to the precise location where a trip begins, such as a person's home, workplace, or a specific business. A 'destination' refers to the precise location where that trip concludes, like a shopping center, school, or another workplace. The primary goal of an O-D study is to map these travel patterns, showing where trips are generated and attracted within a defined area. Data for O-D studies are collected through various methods, including direct household travel surveys where residents log their daily movements, roadside interviews where drivers are briefly stopped and asked about their trip's start and end points, and the analysis of anonymous aggregated digital data from sources like cell phones or GPS devices. Beyond just origin and destination, these studies often gather additional information such as the purpose of the trip (e.g., commuting, recreation), the mode of transportation used (e.g., car, public transit, walking), and the time of day the travel occurs. The comprehensive data gathered from O-D studies is essential for transportation planners and engineers to design new infrastructure, optimize existing road networks and public transportation routes, and accurately forecast future travel demand and potential congestion issues.