  Transportation agencies have an opportunity to leverage
increasingly-available trajectory datasets to improve their analyses and
decision-making processes. However, this data is typically purchased from
vendors, which means agencies must understand its potential benefits beforehand
in order to properly assess its value relative to the cost of acquisition.
While the literature concerned with trajectory data is rich, it is naturally
fragmented and focused on technical contributions in niche areas, which makes
it difficult for government agencies to assess its value across different
transportation domains. To overcome this issue, the current paper explores
trajectory data from the perspective of a road transportation agency interested
in acquiring trajectories to enhance its analyses. The paper provides a
literature review illustrating applications of trajectory data in six areas of
road transportation systems analysis: demand estimation, modeling human
behavior, designing public transit, traffic performance measurement and
prediction, environment and safety. In addition, it visually explores 20
million GPS traces in Maryland, illustrating existing and suggesting new
applications of trajectory data.
