Urban rail
Behind a train journey: platforms, power, signals and the seconds that hold a timetable together.
Follow the flow.
Conceptual stages of an electric urban rail journey, not a real route or track plan. Power, detection, signalling and control support movement continuously; they are not successive places a passenger visits. Arrows indicate a learning sequence, not electrical wiring or permission to operate railway equipment. Select a component to inspect it.
Station access
Entrances, lifts, wayfinding and information connect a railway to the people it serves.
Read the diagram as text
- Station access — Entrances, lifts, wayfinding and information connect a railway to the people it serves.
- Platforms and dwell time — The time spent stopped at a station can shape the capacity of an entire line.
- The train — A train carries passengers while integrating propulsion, braking, doors, control and information.
- Track and support — Rails, fastenings, support layers and drainage keep the train’s path in the required position.
- Braking and energy recovery — Braking reduces motion; regeneration can return some of that energy to a useful electrical destination.
Supporting or alternate roles, not sequential transit stops:
- Signals and separation — Signalling continuously supports safe movement; it is not a passenger stop.
Conceptual stages of an electric urban rail journey, not a real route or track plan. Power, detection, signalling and control support movement continuously; they are not successive places a passenger visits. Arrows indicate a learning sequence, not electrical wiring or permission to operate railway equipment.
You see a train arrive. Behind that ordinary event is an agreement between a moving vehicle, a physical route, an electrical supply and a stream of information. Stations add the human interface: a railway works only when people can reach, board and leave it.
Explore a conventional electric urban railway, using a fictional journey rather than a map of any real city. British and North American examples illustrate particular arrangements; no voltage, signalling technology or accessibility promise is assumed to be universal. The diagram separates the passenger sequence from the supporting systems that operate throughout the trip.
Choose your way in.
Take a train across the city
Follow the passenger, then reveal the systems underneath.
When a longer stop travels down the line
Follow a small change through a connected timetable.
Follow a train’s energy
From the electricity supply to acceleration, then braking.
Before the first passenger boards
Follow a train from preparation to its first useful departure.
After heavy rain, before normal service
Follow water through the railway’s connected dependencies.
Meet the parts that make it work.
Station access
Entrances, lifts, wayfinding and information connect a railway to the people it serves.
Platforms and dwell time
The time spent stopped at a station can shape the capacity of an entire line.
The train
A train carries passengers while integrating propulsion, braking, doors, control and information.
Traction power
Substations and current collectors bring electrical energy from the grid to a moving train.
Train detection
Sensors turn the physical presence of a train into information a signalling system can use.
Signals and separation
Train control preserves enough protected space for movements to remain compatible.
Points and interlocking
Movable track selects the path; interlocking checks whether the proposed movement is compatible with other movements.
Track and support
Rails, fastenings, support layers and drainage keep the train’s path in the required position.
Braking and energy recovery
Braking reduces motion; regeneration can return some of that energy to a useful electrical destination.
Timetables and headway
A service plan coordinates trains, platforms, junctions, crews and maintenance opportunities.
Operations and recovery
Control teams coordinate the service when the railway’s actual state differs from the plan.
Depots and maintenance
A depot turns a fleet of vehicles into trains that are available, prepared and fit for their next duty.
Terminals and turnbacks
Reversing a train requires time and a compatible route, so the end of a line can limit the service along it.
Tunnel ventilation
Shafts, passages, fans and controls connect underground spaces to an environment that trains and people can use.
Drainage and flood resilience
Water routes, storage, pumps and inspections connect a railway to the surrounding catchment and its weather.
A few more seconds at the platform
Change the planned interval and add the same extra dwell to every train at one critical station. Compare spare time and the resulting rate at this one bottleneck.
How do the planned interval and longer stops combine to constrain frequency?
A wider planned gap provides more simplified margin, but schedules fewer trains through this bottleneck.
- Repeat interval
- 120seconds
- Implied rate
- 30trains / hour
- Margin left
- 15seconds
The 105-second occupation still fits within a 120-second interval. 15 seconds of simplified margin remain, so the implied rate is 30 trains/hour. Other constraints and recovery time are outside this model.
03 / Compare A and B
TWO INPUTS. TWO CONDITIONS.Pin the current settings as A, then change either input to test B. A stays in memory only while this page is open. Shared links include the current B inputs, never the pinned A.
No A is pinned. Enable the interactive controls, choose settings and pin them to compare.
| Setting or result | A · Not pinned | B · Current |
|---|---|---|
| Additional dwell at the critical station | — | 15 seconds |
| Planned interval | — | 120 seconds |
| Repeat interval | — | 120 seconds |
| Implied rate | — | 30 trains / hour |
| Margin left | — | 15 seconds |
Inside the modelAssumptions, limits & sources +
At the starting planned interval of 120 seconds, 15 extra seconds make the station occupation 105 seconds and leave 15 seconds of margin. With 45 extra seconds, occupation is 135 seconds and the implied rate is about 26.7 trains per hour. Changing the planned interval changes the comparison; it does not establish an achievable timetable for a real railway.
- This is an original steady-state teaching model of repeated longer stops, not a simulation of one delayed train or a real timetable.
- The planned interval is a second control, from 90 to 180 seconds with a starting value of 120 seconds. A 120-second interval is equivalent to 30 trains per hour if sustained.
- The chosen baseline station occupation is 90 seconds, including the relevant occupation and clearance effects. All other constraints remain fixed.
- Effective headway = max(planned interval, 90 + extra dwell), in seconds. Illustrative sustained throughput = 3600 / effective headway.
- Remaining margin = max(0, planned interval − 90 − extra dwell). A shorter planned interval can offer more trains per hour while leaving less margin at this bottleneck.
- No passenger-crowding feedback, variable braking, junction conflict, turnback, fleet or recovery behaviour is simulated. Actual railway analysis requires these and other details.
Model references: Transportation Research Board / National Academies: Transit Capacity and Quality of Service Manual, Third Edition, Chapter 8: Rail Transit Capacity · National Academies of Sciences, Engineering, and Medicine / Transportation Research Board: Transit Capacity and Quality of Service Manual, Fourth Edition · Network Rail: The timetable
Keep following the connections.
Sources & further reading
Original explanations informed by these sources. Diagrams are conceptual; local systems differ.
- Plan an accessible journey Transport for London · Not stated · Source & rights record
- Using TfL Go for step-free journeys Transport for London · Not stated · Source & rights record
- Review of Transit Station Design Guidelines National Academies of Sciences, Engineering, and Medicine / Transportation Research Board · 2026 · Source & rights record
- Transit Capacity and Quality of Service Manual, Third Edition, Chapter 8: Rail Transit Capacity Transportation Research Board / National Academies · 2013 · Source & rights record
- Transit Capacity and Quality of Service Manual, Fourth Edition National Academies of Sciences, Engineering, and Medicine / Transportation Research Board · 2026 · Source & rights record
- 20-Year Needs Assessment: New York City Transit appendix Metropolitan Transportation Authority · 2023 · Source & rights record
- Third rail Network Rail · Not stated · Source & rights record
- Planned works Network Rail · Not stated · Source & rights record
- Electrification Network Rail · Not stated · Source & rights record
- Recycled energy on Tube trains (2) London Assembly / Mayor of London · 2015-11-23 · Source & rights record
- London Underground: Safety Certification and Safety Authorisation, version 6.2 London Underground / Transport for London · 2022 · Source & rights record
- Track circuits explained Network Rail · 2019-09-30 · Source & rights record
- Signals explained Network Rail · 2018-09-05 · Source & rights record
- Axle counting systems Siemens Mobility · Not stated · Source & rights record
- Signals and points failure Network Rail · Not stated · Source & rights record
- The timetable Network Rail · Not stated · Source & rights record
- A greener railway: more environmentally friendly sleepers Network Rail · 2024-07-24 · Source & rights record
- Track treatment fleet Network Rail · Not stated · Source & rights record
- Buckled rail and summer heat Network Rail · Not stated · Source & rights record
- Flooding Network Rail · Not stated · Source & rights record
- Operational Rules Network Rail · Not stated · Source & rights record
- Knock-on delays Network Rail · Not stated · Source & rights record
- How we keep you updated when there’s a delay Network Rail · Not stated · Source & rights record
- Behind the scenes: Sydney Metro operations Sydney Metro / Transport for NSW · 2022-08-24 · Source & rights record
- Construction completed at Sydney Metro Trains Facility South Sydney Metro / Transport for NSW · 2024-06 · Source & rights record
- Through-Running Regional Rail: Results, section 9, Turnback Operations National Academies of Sciences, Engineering, and Medicine / Transportation Research Board · 2026 · Source & rights record
- Hunter Street Station Newsletter: turnback tunnels Sydney Metro / Transport for NSW · 2024-06 · Source & rights record
- Information Paper A4: Ventilation and Intervention Shafts, version 2 Crossrail · 2007-11-20 · Source & rights record
- Aboriginal artwork adorns Central Station ventilation buildings Sydney Metro / Transport for NSW · 2022-09-15 · Source & rights record
- The Design of Thermal Tunnel Energy Segments for Crossrail Duncan P Nicholson, Qing Chen, Mike de Silva, Alan Winter and Ralf Winterling; Crossrail Learning Legacy / ICE Publishing · 2014-11-03 · Source & rights record
- Fourth Adaptation Report Network Rail · 2024-12 · Source & rights record
- Asset Management: Weather Resilience and Climate Change Adaptation Plan Network Rail · 2021-05 · Source & rights record