1.   New York City has used barges before to handle periodic overflows of detainees from its jails.

2.   The city has long used barges to move trash from Manhattan to its Fresh Kills landfill in Staten Island, which closed earlier this year.

3.   The barges were used during the Middle Ages by merchants in northern Europe to transport goods.

4.   The organisation is aiming to use barges to transport some of the aid from Kigoma, in Tanzania, as well as lorry convoys.