[johansch]

http://www.forbes.com/sites/wadeshepard/2016/01/28/why-china...

However, this article says:

"The exit customs inspection for the Su’Man’Ou trains is done on-location in the bonded zone. The next time these containers will need to go undergo a customs inspection will be at the border of the EU, and they will typically not be opened until they arrive at their destination."

and

"These cargo relays are generally very simple procedures: the incoming train and the outgoing train are lined up side by side and a crane moves the containers from one to the other. At Khorgos Gateway, a new junction on the Silk Road Economic Belt on the border of Kazakhstan and China, this transfer can be done in just 47 minutes."