Deliveries will take place between mid-2017 and the second quarter of 2018, with the vehicles being assembled at Siemens' Simmering plant in Vienna. The contract includes an option for six additional vehicles.
The 31.5m-long LRVs will accommodate up to 175 passengers and the order is the first Siemens has received for the multi-articulated version of the Avenio.
Ulm needs additional trams for its second tram line, which will run for 10.5km from the Science Park in the northwest of the city to the main station and Kuhberg in the southwest. The 20-station line will share tracks with Line 1 for 1.2km in the city centre.
The line is due to open in 2018 and is forecast to carry around 8300 passengers per day.
In April Germany's Federal Ministry of Transport and Digital Infrastructure (BMVI) approved a €65m grant for the €155m project, which is being facilitated through the Municipal Transport Financing Act (GVFG). The remaining funds will come from the city of Ulm and the state of Baden-Württemberg.
Line 2 was finally approved by Ulm city council on May 6.