 During this time, a high-profile project performed with early PEMS equipment was the World Trade Center (WTC) Ground Zero Project in lower Manhattan, testing concrete pumpers, bulldozers, graders, and later - diesel cranes on Building #7 - 40 stories high.Other early PEMS projects such as Dr. Chris Frey's field work was used by the USEPA in the development of the MOVES Model.However, users such as regulators and vehicle manufacturers had to wait for ROVER to be commercialized to conduct actual measurements of mass emissions rather than depend on estimates of mass emissions using data the OBD port, or a direct engine measurement, in order to have a more defensible data set.