Flyover track Lego City High speed Passenger train 60051

The flyover track had to be made a certain height because of the engine capacity of train, if the flyover track is too high then the train struggled to move forward and backwards. Also for moving on flyover, the train should be going at maximum speed and at a certain distance. When the train is coming down from flyover, the speed should be decreased immediately otherwise the train will derail. Thank you for watching