Timetables and headway

Its job in the system

A public timetable tells passengers when to travel. The operational plan contains much more: empty train movements, depot access, intermediate timings and the use of shared infrastructure. On a frequent metro, the passenger promise may be a regular interval rather than a departure minute, but the railway still needs an achievable plan behind that promise.

How it works

Headway is the time between successive trains at a specified point. A scheduled two-minute headway corresponds arithmetically to 30 trains per hour if sustained. That calculation is not proof that a particular railway can deliver it. The limiting station, signalling arrangement, junction or turnback can require more time, and variation in actual operation needs allowance.

Operating margin creates room for small disturbances without immediately forcing the following train to wait. It is not an invitation to disregard safety limits. A plan that uses every theoretical second may be fragile: one extended station stop can meet the next train’s path. A more robust pattern can provide a better passenger service than a higher advertised frequency that repeatedly breaks down.

What it connects to

Timetabling connects nearly every component in this family. It must match fleet availability, station dwell, power demands, route conflicts and maintenance access. Turnbacks matter too: a train reaching the end of its route must be ready for its next trip. Delays can therefore return in the opposite direction through the same train or crew.

Different places, different designs

A self-contained metro differs from a railway shared with express, regional or freight trains. Different speeds and stopping patterns can consume additional capacity. The British working-timetable example illustrates this coordination; it does not prescribe planning rules for every city. Our numerical scenario isolates one bottleneck and deliberately omits the complete scheduling problem.