SimDesk in Action: Running 775 ETCS Test Scenarios

What You're Watching

This recording shows SimDesk — our Tauri 2.0 desktop application — executing ETCS standardized test sequences from SUBSET-076 against the real SS026 EVC implementation. The simulation runs in physics mode: a closed-loop system where the EVC, RBC, and train dynamics simulator interact in real time.

The Interface

SimDesk provides a unified view of the entire ETCS system during test execution:

Speed Gauge (Left)

The circular gauge is a faithful reproduction of the ETCS Driver Machine Interface (DMI) speed display. It shows:

• Current speed — the large number in the center, updated every EVC cycle
• Permitted speed — the green arc boundary that the train must not exceed
• Supervision status — color changes (green/yellow/orange/red) reflecting the EVC's supervision state machine (Normal, Over-speed, Warning, Intervention)

Timeline View (Top)

The horizontal bar represents the track ahead, with:

• Speed profile — the green/yellow line showing permitted speed along the route
• Train position — the moving marker tracking where the train is on the track
• Gradient changes — visible as profile shifts along the distance axis

Scenario Panel (Center)

Each test scenario is an SS-076 standardized sequence — a precise series of inputs and expected outputs defined by the European Union Agency for Railways. The panel shows:

• Scenario name — e.g., "Train Trip and Recovery," "Speed Profile Compliance," "Unconditional Emergency Stop"
• Description — what the scenario tests and what the EVC should do
• Step progress — how many of the scenario's steps have been executed

System Status

The subsystem indicators show the state of all six on-board components:

EVC State (Right Panel)

The right sidebar displays the real-time internal state of the European Vital Computer:

• Level — current ETCS operating level (0, 1, 2, or 3)
• Mode — current operating mode (Full Supervision, Stand By, Trip, etc.)
• Speed — current train speed with permitted/target values
• Position — LRBG-relative position with confidence intervals
• Emergency Brake / Service Brake — brake command status
• Events — rolling list of JRU events as they occur

Event Log (Bottom)

The scrolling log at the bottom shows every significant event: mode transitions, brake commands, balise passages, radio messages, and driver actions — the same events that would be recorded by the JRU in a real train.

The Test Scenarios

The recording runs through several SS-076 test categories:

Train Trip and Recovery

The EVC enters Trip mode (TR) — the safety state triggered when the train violates a movement authority or receives an emergency stop command. The test verifies that:

• The EVC correctly latches the emergency brake
• The train decelerates to standstill
• The driver can acknowledge and recover from Trip
• The EVC transitions back through Post Trip to the correct operating mode

Speed Profile Compliance

Tests the EVC's supervision curve computation — the core safety function. The train runs through a route with multiple speed changes, and the EVC must:

• Compute correct permitted, warning, and intervention speeds
• Apply braking curves that respect train braking capability
• Handle gradient compensation (uphill/downhill affects braking distance)
• Transition between supervision states (Normal → Over-speed → Warning → Intervention) at the correct thresholds

Unconditional Emergency Stop

Verifies the EVC's response to a SUBSET-026 §3.10 unconditional emergency stop from the RBC. This is a critical safety function:

• The EVC must immediately command emergency braking
• No driver acknowledgment is required or allowed
• The train must reach standstill before any recovery is possible
• The correct ETCS mode transitions must occur (FS → Trip)

How the Simulation Works

SimDesk embeds the SimEngine library directly via Tauri IPC — no external processes or MQTT brokers needed. The simulation loop:

1. EVC cycle — the etcs-evc-core crate runs its 7-phase cyclic executive (read inputs → process odometry → update kernel → compute braking → check procedures → generate outputs → record events)
2. Train dynamics — Newtonian physics simulation applies traction, braking forces, gradient, and resistance to compute speed and position
3. RBC response — the etcs-rbc crate processes position reports and issues movement authorities
4. 50 physics sub-cycles — between each test step, 50 physics iterations run to let the system settle, ensuring realistic time-domain behavior

This is closed-loop testing: the EVC's brake commands actually decelerate the simulated train, and the resulting speed feeds back into the EVC's next cycle. Nothing is faked.

The Numbers

What you see in this recording is part of the 775 SS-076 test sequences that all pass at 100%:

• 69,857 total test steps executed across all scenarios
• 0 steps skipped — every step runs through the real EVC implementation
• Strict verification on DMI mode display, level display, and TIU brake commands
• Physics mode validates real-time behavior, not just logical correctness

SimDesk is built with Tauri 2.0 (Rust backend + Vue 3/Vuetify frontend) and is part of the SS026 project — an AI-defined safety-critical ERTMS/ETCS implementation.