А что они тогда тестировали и испытывали?

Brussels needed new trams and Siemens took the opportunity to test the Combino in Brussels. This is not a superfluous luxury: there are steep gradients, tunnels with complicated junctions, and so on. These tests also took place, but only at night.
In the end, Brussels opted for the CityRunner of Bombardier and 219 trams were bought, with which they are very satisfied.