The term «slot» denotes a journey on a specific track at a specific time by a specific train. Since 1991 it has been not just a logistical unit but also an economic one. When a transport operator acquires a slot, it obtains the right to use a specific stretch of line at a specific time. Since trains run at different speeds and some stop more than others, the number of slots available is limited - and the complexity of planning them infinite. The process of sharing out the increased number of slots made available by the NRLA involves weighing up various needs: the financial viability of the railway, the time constraints on passengers, and keeping traffic flowing constantly.
« A path (comparable to a ‘slot’ in air traffic) is the right to drive a train along a specific stretch of railway at a fixed time. »Swiss Train Paths Ltd, Swiss Train Paths Ltd brochure, November 2012