Propane restrictions on Maryland tunnels limited to 10 lb containers of propane gas with a limit of 10 containers :h:
Code of Maryland Regulations (COMAR) govern the transport of hazardous materials across our toll facilities. Under these regulations, vehicles carrying bottled propane gas in excess of 10 pounds per container (maximum of 10 containers), bulk gasoline, explosives, significant amounts of radioactive materials, and other hazardous materials are prohibited from using the Fort McHenry Tunnel (I-95) or the Baltimore Harbor Tunnel (I-895). The Francis Scott Key Bridge (I-695, the Baltimore Beltway) is a convenient alternative route for crossing Baltimore's Harbor.
If you are not making any stops between Yorktown and Suffolk Va, I can give you advice on driving through. The traffic is slower city and slower rural, with many traffic lights if you try to follow rt 17 exactly until you get to Suffolk.