Ad hoc path

An ad hoc path is a train path requested outside the annual timetable planning cycle — placed after the working timetable has been set and running against residual capacity, at shorter notice than the standard annual process.

Under EU rail capacity allocation rules, the standard route for securing train paths is the annual working timetable process, which closes roughly 11 months before the timetable period begins. Operators with needs that are not foreseeable at that stage — typically spot freight traffic, charter movements, or demand responses — use ad hoc requests instead.

Ad hoc requests can in principle be placed at any time after the annual timetable has been finalised, including hours before a planned train run, though guaranteed response times vary significantly by infrastructure manager and network. The Recast Directive (2012/34/EU) requires infrastructure managers to accommodate such requests where capacity exists.

The practical limitation is structural: ad hoc requests compete for whatever capacity remains after annual and late-request allocation. On congested networks and corridors, residual capacity is often limited or unavailable at the times operators need.

This creates a commercial disadvantage for freight operators whose customers need flexible, short-notice booking — which is one driver behind the EU’s Timetabling and Capacity Redesign (TTR) reform process, which seeks to make more capacity available dynamically throughout the timetable period.

On international Rail Freight Corridors, infrastructure managers collectively define Reserve Capacity — pre-set contingents of slots specifically intended for international ad hoc requests — which can be accessed from 30 days before the planned train run.