Vendor’s compliance with FRA guidance. Vendor officials told us the other reason it has not yet met FRA requirements is because they believe that the regulation governing model validation is ambiguous about what is ultimately needed. Vendor officials also told us the FRA requirements related to computer modeling are significantly different than how they verify trainset safety in Europe where the vendor is based. FRA and DOT officials said they have been working closely with the company and the vendor to answer questions and help them comply with the requirements, including demonstrating a step‐by‐step process on how to comply. For example, as early as October 2017, the DOT subject matter expert outlined in detail to the company and the vendor the steps they needed to take to comply with the requirements. Additionally, company officials said that as early as July 2021 and many times since then, they offered to assist the vendor in its model validation efforts. For example, company officials said they offered to troubleshoot challenges in developing the computer model itself within the software the vendor uses, including an in‐person session in Montreal, Canada, in fall 2021. In January 2023, the vendor’s Chief Executive Officer, the company’s Chief Executive Officer, and other executives began meeting regularly to discuss the model validation process and other issues related to maintaining the legacy fleet. Despite these offers to assist the vendor and the recent executive‐level discussions, the vendor has denied the company and DOT subject matter experts direct access to the trainset model input files, according to program documents and officials from the company, FRA, and DOT. During a March 2023 interview, vendor officials told us the contract does not require them to share the trainset model. Vendor officials said that the input files were their intellectual property and sharing them would risk disclosing proprietary information.