The U.S. Department of Transportation, through the John A. Volpe National Transportation Systems Center, is seeking to renew two licenses for the NUCARS software, which is critical for conducting rail dynamics studies. The NUCARS software is the only validated simulation package capable of predicting the nonlinear dynamic response of North American railroads, making it essential for accessing decades of simulation results previously generated by Volpe Center engineers. The procurement is classified as a sole source award to Transportation Technology Center, Inc. DBA MxV Rail Software Products, due to the proprietary nature of NUCARS and the significant costs and delays associated with transitioning to alternative software. Interested parties can contact Darcy Hubbard at darcy.hubbard@dot.gov or by phone at 617-494-3816 for further details.