The buses are running on three lines – 7, 9 and 17 – for a trial period until September 22nd, Lausanne's public transport services (TL) said in a statement.
The 25m-long, double-jointed trolleybuses have a capacity of 150, up from 110 for regular buses, and can run at 18km/hr.
They have been loaned to the city by Lucerne, which has been trialling the extra-bendy buses for a while and is in the process of integrating them into its transport system.
During Lausanne's test period the new buses won't take passengers, apart from on September 9th when people may board one on the number 9 route.
The point of this technical trial period is to see what type of urban planning will need to be done in order for the buses to operate effectively in the city, such as lengthening bus stops, a TL spokesman said.
The company will also evaluate the impact of the buses on TL itself, in terms of maintenance and parking facilities.
Any necessary roadworks will be funded by the commune, with federal and cantonal support, said news agency ATS.
A roll-out of the buses isn't expected until 2022.