When designing the layout of a coaster track, all features have to consider if the cart can pass through without much trouble and complete the track without suddenly slowing down. To do this, all part of the train of cart must be observed. You have to remember that the coasters are a train of multiple carts and each cart is not experiencing the same forces as others and this may affect how the train of cart performs on the track. This is shown in the picture as one cart feels forces downwards, while an other  feels it mostly upwards. Each force jars at part of the cart in different direction. These forces can slow down the coaster and the loss would need to be considered later on in the track to make sure the coaster reaches the end. If these forces are not considered, the coaster may not function properly as it coasts through the track and may not function correctly. This can lead to problems later on such as rapid degradation of part on the coaster that can lead to accidents.