HS2 Phase 1 has a committed operational service requirement of 10 trains per hour (tph) in each direction once London Euston is fully operational [1]. This represents the planned service frequency that balances demand across the dedicated high-speed line and connections via the West Coast Main Line to northern destinations.

The infrastructure itself is designed with significantly higher maximum capacity. The line's core infrastructure can accommodate up to 18 tph in the busiest sections, providing future-proofing for potential service increases beyond the initial committed level [1]. This distinction between committed operational service and maximum infrastructure capacity is important: the 10 tph figure represents what HS2 Ltd and the government have committed to deliver, while 18 tph reflects the physical capability built into the system.

During the interim period before Euston completion, when services are expected to terminate at Old Oak Common, the frequency will be reduced to approximately 6 tph due to operational constraints of using that station as a temporary terminus rather than a through-station [1]. Once Euston opens, the service is expected to ramp up to the full 10 tph planned level.

The 10 tph service pattern is expected to include approximately 3 tph serving Birmingham Curzon Street directly, with the remaining 7 tph continuing northward via the Handsacre Junction to serve destinations such as Manchester, Liverpool, and Scotland. However, the exact destination-by-destination breakdown remains subject to detailed timetabling and is not yet fully committed in public baseline documents.