Three complete Thameslink Desiro City carriages will make their world premiere next month at Innotrans 2014.
Siemens is manufacturing 1,140 Class 700 carriages for the new Thameslink, Southern and Great Northern (TSGN) franchise, which Govia begin operating in September.
The first of the new Desiro City trainsets will go into service in 2016 on the existing Thameslink route. In 2018, the full peak service of 24 trains per hour will operate in and out of London Bridge.
A programme of climatic testing has already been completed and a Class 700 trainset recently hit 160 km/h while conducting trial runs on the Wegberg-Wildenrath test circuit in Germany.
The Department for Transport (DfT) confirmed the £1.6 billion order with Siemens in the summer of 2013- two years after the German manufacturer was named as the preferred bidder for the contract.
As well the new trains, the order has required Siemens to build two new depots at Three Bridges and Hornsey to maintain and repair the fleet.