FYI - most empty/residue placarded cars need to be buried by at least 1 car from the engines or occupied caboose.
Loaded cars have to be buried by 5 cars if train length permits (ie if there are 5 non hazmat cars in the train to use as spacers). This is why they get away with only using 1 spacer in unit trains.
There are exceptions to the rule - some placarded cars are not considered hazmat like the Sodium Chlorate (UN 1495)hoppers and hot asphalt tankers (UN 3257) - they can all go right next to the engines.
Loaded cars have to be buried by 5 cars if train length permits (ie if there are 5 non hazmat cars in the train to use as spacers). This is why they get away with only using 1 spacer in unit trains.
There are exceptions to the rule - some placarded cars are not considered hazmat like the Sodium Chlorate (UN 1495)hoppers and hot asphalt tankers (UN 3257) - they can all go right next to the engines.