What is the minimum height of train tunnels in the US?

The minimum height for train tunnels in the U.S. is typically set at around 21 feet (6.4 meters) to accommodate the standard clearance for most freight and passenger trains. However, specific requirements can vary based on the type of rail service, the region, and local regulations. Some tunnels may have higher clearances to accommodate double-stacked containers or specific types of rolling stock. Ultimately, standards are determined by the Federal Railroad Administration and may differ across various rail networks.