FTA defines oversight as a continuous review and evaluation of grantee and FTA processes to ensure compliance with statutory, administrative, and regulatory requirements. The Office of Engineering, through the Regional Offices, performs oversight of grantee project management that focuses on the management of major investments (New Starts, rail modernization, etc.) in transit projects. This activity begins early in project implementation, usually at the time of preliminary engineering. PMO contractors monitor the large caseload of projects, following guidelines established by FTA. They serve to supplement the FTA technical staff to evaluate grantee project management and technical capacity and capability to successfully implement these major transit projects. They also monitor the projects to determine whether they are progressing on time, within budget, and in accord with approved grantee plans and specifications. Other activities are also involved, such as reviews of whether a given design can in fact be constructed, change order reviews, and value engineering.