The Campus Transit Lab (CTL) integrates non-automated data collection activities with automated technologies to create a comprehensive platform supporting research, education, and outreach. One such activity currently conducted at the CTL is an extensive passenger origin-destination (OD) flow field survey. These "onboard" surveys, which detail the locations where individual CABS passengers board and alight, typically capture 95% of the passengers on a sampled bus trip. To date, OD trip pairs covering 5 bus routes, 325 bus trips, and over 15,000 passengers have been recorded. OD flows collected during these field surveys can elicit information about campus travel patterns and be utilized as a "ground truth" from which empirical evaluations of various methods that estimate OD flows can be made.