Take a train across the city
Trace a fictional journey between two stations on an electric urban railway. Every stage depends on more than the train itself.
Reach a usable route
You enter the station and find the correct platform. The useful route includes entrances, circulation space, information and any lifts or ramps you need. An interchange shown on a map is not automatically step-free. The journey begins with a continuous passenger path from the street to the boarding point. The destination needs the same continuity check.
Look for a continuous route from the street through any transfer to the intended boarding point.
A train service is useful only when the passenger can reach and use it.
Read the complete journey
- 1
Reach a usable route
You enter the station and find the correct platform. The useful route includes entrances, circulation space, information and any lifts or ramps you need. An interchange shown on a map is not automatically step-free. The journey begins with a continuous passenger path from the street to the boarding point. The destination needs the same continuity check.
Notice: Look for a continuous route from the street through any transfer to the intended boarding point.
Explore Station access
Why: A train service is useful only when the passenger can reach and use it. - 2
Exchange passengers
The arriving train stops and passengers leave before new passengers board. Doorways and platform circulation become the active interface. The stop needs enough time to complete safely, but a long stop also keeps the platform occupied. Its effect on following trains depends on the available time margin and separation arrangements.
Notice: Notice how the busiest doorway can stay active after other doorways have finished exchanging passengers.
Explore Platforms and dwell time
Why: The last part of the passenger exchange can affect when the whole train is ready. - 3
Supply the departure
As the train accelerates, its traction equipment draws electrical energy from the railway supply. A substation and a moving collector connect it to that system. This energy path runs alongside your passenger journey. Other trains may be drawing power or returning braking energy at the same time, so the supply serves a changing pattern of demand.
Notice: Trace the electrical supply alongside the passenger route, rather than ending the energy path at the station.
Explore Traction power
Why: The moving train needs a continuous compatible supply arrangement during its duty. - 4
Move within permission
The train proceeds within the movement permissions and speed limits of its control system. Detection, route status and protection functions support that permission. The driver or automatic driving equipment does not merely aim for the next station on a map: it responds to the current protected movement available ahead. That permission can change during the trip.
Notice: Separate the line drawn on a passenger map from the protected movement available ahead of the train.
Explore Signals and separation
Why: A destination does not establish permission to occupy every part of the route immediately. - 5
Follow the physical railway
Wheels follow rails whose alignment and support carry the train through the city. At a junction, points select a route only within the required control arrangements. Curves, gradients and other trains can constrain the motion. The line on your passenger map leaves out most of this physical and operational detail.
Notice: Look beyond the rails to their supports and to any junction that changes the available path.
Explore Track and support
Why: The train depends on a maintained physical structure and a compatible route. - 6
Travel through a managed underground environment
For this part of the fictional trip, the train enters a tunnel. Its movement also displaces air, while trains and other equipment release heat. Ventilation routes and equipment help manage that enclosed environment according to the local design. The gust you might notice is one visible clue to a supporting network that the passenger map rarely shows.
Notice: Notice the connection between a passing train, moving air and the station or tunnel’s ventilation openings.
Explore Tunnel ventilation
Why: An underground journey depends on environmental systems as well as track and train control. - 7
Slow, stop and continue on foot
Braking reduces the train’s motion for the destination stop. Where equipment and the electrical network permit, some energy can be recovered. You leave the carriage and follow the destination station’s accessible route to the street. The successful trip has joined passenger movement, energy, information and physical infrastructure. The train now prepares for another departure.
Notice: Follow the destination exit as well as the train’s stopping point.
Explore Braking and energy recovery
Why: The passenger journey continues after the vehicle has arrived.
Which supporting systems are still needed while the train is travelling between stations?
Reveal the explanation
The train still depends on a physical track, a compatible energy supply and valid movement permissions supported by detection and control. In an underground section it also depends on the relevant ventilation arrangements. Passenger boarding is only one interface in the journey.
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
- Third rail Network Rail · Not stated · Source & rights record
- Signals explained Network Rail · 2018-09-05 · Source & rights record
- Track treatment fleet Network Rail · Not stated · Source & rights record
- Recycled energy on Tube trains (2) London Assembly / Mayor of London · 2015-11-23 · 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
Another way through the system.
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.