In the past decades, we have learned to accept that the capacity of freeways is limited, and that designing freeways with such capacities that daily congestion can be avoided is often not optimal from both a social and an economic point of view. This paper studies the potential benefits of slot reservation. Slot reservation implies that users do no longer have random access to certain freeways; instead they have to reserve a slot in advance. By analysing the difference between user equilibrium departure times and system optimum departure times, it appears that, theoretically, all queuing costs can be eliminated without increasing the mean rescheduling costs. The magnitude of this cost reduction is about 50%. Alternatively, congestion pricing could be used to help to restore the balance between supply and demand. However, this solution has a number of disadvantages, including the problem that the toll raisers have limited knowledge about the future traffic demand, and the limited acceptance of welfare redistribution effects by the public. Thus, it can be concluded that slot reservation is an interesting option, though the final conclusion can only be based on a complete assessment of both the benefits and the costs of the system.