Traincar asset has invalid length.
KIND Traincar assets use "a.limfront" and "a.limback" attachment points to indicate the absolute front and back position of the vehicle along the y-axis. Typically, the "a.limfront" will be at a negative value on the y-axis, while the "a.limback" will be at a similar-magnitude positive value on the y-axis. This validation error results when there is insufficient separation between these attachment points.
This validation results in an error at trainz-build 4.5 and higher. In lower trainz-build assets, the validation is considered a warning for compatibility reasons, however it is likely to lead to undesirable runtime behaviour.