The Safe Freight Act of 2024 requires major Class I railroad carriers to operate freight trains with a minimum two-person crew consisting of a certified conductor and locomotive engineer. The law applies primarily to trains operating on heavily-trafficked main line tracks and to high-hazard trains carrying dangerous materials like flammable liquids, explosives, or toxic substances. Certain operations are exempt from this requirement, including trains on non-main line tracks, locomotives providing roadside assistance, short-distance locomotive movements under 50 miles, and some train operations that were already staffed with smaller crews before the law's enactment. However, high-hazard trains and trains exceeding 7,500 feet in length cannot use these exemptions and must always operate with two-person crews. The bill allows railroads to request waivers from these requirements and preserves the Secretary of Transportation's authority to enforce safety standards.