In general, obstacles are perfectly normal. The trick is to use the energy of engaged and committed employees to sufficiently clear the obstacle so the cart can keep moving. If it becomes clear that the task of moving the obstacle is proving too hard for the employee, it is essential that the job is passed onto someone else. When employees are stuck with a frustrating task for too long, there runs the risk that they can go from leading the cart along its journey, to disrupting the journey.