Signalling interfaces, tunnel ventilation and possessions
Commissioning software for rail and metro projects where every test runs inside a possession, and the safety case depends on the evidence.
Rail and metro commissioning is constrained by possession windows, governed by a formal safety case, and dependent on interfaces between station M&E, tunnel ventilation and a signalling system that is rarely under the same contractor's control. Deskely tracks assets, interfaces and possessions in one register so the safety case is supported by evidence rather than assembled retrospectively.
- Interfaces
- Signalling, power, ventilation
- Constraint
- Possession windows
- Governance
- Formal safety case
- Gate
- Entry into service
Choose your project type
The problem
A possession is booked months in advance, and it is wasted the moment one prerequisite is unsigned.
Testing on live or soon-to-be-live rail infrastructure happens inside possessions negotiated far in advance across multiple contractors and the infrastructure manager or operator.
When readiness for that possession is judged from a status call rather than from signed prerequisite records, the possession is granted, the crew mobilises, and the work cannot proceed because one interface was never actually proven.
Deskely reports readiness against the specific tests a possession depends on, so the decision to proceed is made on evidence before the possession is confirmed, not discovered once it starts.
Setting up the register
Station assets, tunnel systems and interfaces sit in one register even though they answer to different parties.
Station M&E, tunnel ventilation fans and dampers, and the interface points to the signalling and train control system are each modelled as assets, with the party responsible for each interface recorded against it.
Cause-and-effect matrices for tunnel ventilation and smoke control in an emergency scenario are held as their own test set, because they typically sit at the centre of the fire and life safety case.
Because responsibility for each interface is explicit, a gap between what the M&E contractor tested and what the signalling contractor tested becomes visible before it becomes an incident.
Possession-based testing
Every test is tied to the possession that made it possible, not just to a date.
Functional tests, interface tests and integrated systems tests are recorded against the possession in which they ran, with any incomplete test automatically flagged for the next available window rather than lost.
Signalling interface testing — train detection, points, interlocking boundaries with new station or tunnel systems — is recorded jointly where more than one contractor's sign-off is required.
Tunnel ventilation performance testing under normal and emergency operating modes is captured with the specific scenario and setpoint it was proving, which is what a safety case reviewer needs to see rather than a pass/fail summary.
Safety case and entry into service
Entry into service depends on a safety case that is only as strong as the records behind it.
The safety case submission draws directly on signed test records, interface sign-offs and cause-and-effect validation held in the register, rather than a separate evidence-gathering exercise run after testing finishes.
Independent safety assessors and the infrastructure manager or operator both need to trace a claim in the safety case back to a specific signed record — a structure the register is built to support from the outset.
Because every record carries a name, role and timestamp, gaps identified during safety case review can be closed against the specific asset or interface rather than reopening the whole testing programme.
Traction power and OLE energisation
Energising the overhead line turns every subsequent test into a live electrical operation with its own permit.
Once traction power is live, testing on or near the running line moves under electrical safety rules that did not apply during construction: isolation and earthing procedures, competent person sign-off and a formal permit-to-work sit ahead of any further signalling or platform equipment test.
Depot commissioning — stabling roads, wheel lathes, train wash plant and the interface between depot control and the mainline signalling system — typically runs on its own schedule, separate from station and tunnel possessions, and is easy to lose track of against the wider programme.
Deskely records energisation permits, isolation certificates and depot commissioning tests against the same asset and possession model used for the rest of the programme, so a signalling test that depends on a live OLE section shows its electrical prerequisite as a gate, not an assumption.
Evidence
The entry-into-service dossier
Entry into service is a safety case decision, and the safety case is only as strong as the possession-window test records feeding it. Signalling, ventilation and platform interfaces each need their own dated, witnessed evidence.
Tunnel ventilation integrated test record
Jet fans and ventilation shafts achieve the modelled airflow in normal and emergency mode
During a dedicated possession, before entry into service
Platform-edge-door interface test log
Door alignment, obstacle detection and train stopping accuracy meet the interface control document
After platform fit-out, before passenger trial running
Signalling and power interface sign-off
Traction power, signalling and station systems interoperate without conflict at defined boundaries
Following individual system testing, before integrated running
Emergency evacuation and egress trial record
Passenger evacuation via cross-passages or platforms meets the safety case assumptions
Live trial, witnessed by the independent safety assessor
Station fire and smoke control witness test
Smoke extract and pressurisation systems respond correctly to the platform and concourse fire scenario
Joint witness with fire authority, ahead of opening
Independent safety assessor (ISA) sign-off
The completed works satisfy the approved safety case and may enter passenger service
Final gate preceding entry into service
How it runs
From possession planning to entry into service.
Rail and metro programmes need the register structured around possessions and interfaces before the first test is booked, because both drive the safety case.
- 01
Model interfaces by party
Station, tunnel and signalling assets tagged with the contractor or authority responsible for each interface.
- 02
Template possession-linked tests
Functional, interface and cause-and-effect tests defined once, tied to the possession each depends on.
- 03
Capture results in the window
Test results, including joint sign-off where required, recorded on-site during the possession itself.
- 04
Build the safety case from evidence
Safety case submission drawn directly from signed records, with gaps traceable to a specific asset or interface.
FAQ
Questions about Rail and metro scopes.
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