Most trademarks filed are words and logos, the more traditional trademarks. Consumers usually focus on these kind of trademarks. Non traditional trademarks like colours and 3D trademarks can be distinctive too, think of the bottle of Coca-Cola. However, as consumers tend to focus on traditional marks, in practice is harder to convince trademark offices of the distinctiveness of non traditional trademarks.
When you think of the ICE, the German high speed train, many people will think of a white train with a red stripe. So, registering the 3D train as a European trademark is not a bad idea. Strange enough, the other remarkable European train, the TGV, has not been registered. Actually just one other train has gained protection as a 3D trademark: Thomas the Tank!