Transportation Workforce Modernization Act This bill directs the Department of Transportation (DOT) to provide grants to institutions of higher education (IHEs) and other entities to develop a curriculum for and establish transportation worker training programs in urban and rural areas for workers whose jobs may be changed or worsened, or who may have been separated from their jobs as a result of being replaced by the adoption of automated driving systems. The Government Accountability Office (GAO) must study and report on the impact of driverless vehicle adoption on specified sectors of the economy. Additionally, DOT must seek to enter into an agreement with an IHE or nonprofit organization to conduct research on such impacts for inclusion in the GAO study.