Interestingly, they are supposed to be connecting while moving:
One of its unique features is the proposal for trams to automatically connect to each other while in motion. It is planned that up to three trams can be linked within the city, and even more on suburban routes. Each 17-meter-long tram is designed to accommodate 140 passengers.
(source)
Definitelly cool - even though I struggle a bit to find a practical justification. Maybee to be able to spread the passengers more equally among free seats ?