Demurrage and detention can happen for a variety of reasons: when the containers are not being picked up due to port congestion, limited chassis supplies, customs exams, lack of truckers, etc. 

Demurrage charges can be difficult to plan your way out of, as these circumstances can be unknown at the time of booking or arrival. 

Detention charges most often occur due to a lack of clarity around who is supposed to report back to the truckers when the containers are empty and ready to be returned. When miscommunication happens between supplier, trucker and the logistics partner, then containers are stranded outside the ports for longer periods of time. This means that detention charges may apply.