The aim of a time slot booking-system is mainly to avoid waiting time at the loading or unloading place. A freight forwarder or driver who wants to unload cargo at a supermarket, for example, must book a time via a portal (time slot booking-system). In the portal you can see which times are still free at the unloading place and can be booked (e.g. 2:00 p.m. - 3:00 p.m.). The driver should arrive as punctually as possible. Short waiting time can occur. If the driver cannot make it on time, because of a traffic jam or an accident, he has to book a new time. It is similar to aircraft dispatching. Airlines have "time slots" in which a flight must take place. Otherwise, the time slot expires and they must face harsh penalties.