JME - Application Documentation
    Preparing search index...

    JME - Application Documentation

    JME - Junction Modeller Expanded

    A 3D traffic simulation platform for designing, analysing, and visualising junction networks. Build intersections and roundabouts, connect them with road links, run realistic traffic simulations, and evaluate performance with industry-standard metrics - all in the browser.

    # Install dependencies
    npm install

    # Start the development server
    npm run dev

    # Production build
    npm run build
    npm run start

    Open http://localhost:3000 in a modern browser.

    Mode Description
    View Free-orbit 3D camera. Watch simulations, follow vehicles in first-person, and inspect statistics.
    Build Top-down orthographic view. Place junction objects, drag to position, configure exits, and create links.

    Switch between modes using the Modes dropdown in the header.

    • Polygonal junction body with configurable exit arms (3–6 exits).
    • Traffic light phases cycle through GREEN → AMBER → RED-AMBER → RED for each arm.
    • Vehicles obey stop lines, respect signal colours, and detect queue build-up.
    • Circular island with radiating exit arms (3–6 exits).
    • Vehicles give way to ring traffic, enter when a safe gap is detected, and exit from the ring.
    • Includes timeout-based forced entry to prevent infinite queueing.

    Each exit can be individually tuned:

    Option Range Description
    Num Lanes In 1–3 Inbound lanes entering the junction
    Lane Count 1–4 Outbound lanes leaving the junction
    Exit Length 10–60 Length of the exit arm (world units)
    Spawn Rate - Optional per-exit spawn rate override

    Select a junction object by double-clicking it in Build mode to open the Selection Panel with these options.

    1. In Build mode, click on an exit of one junction - it highlights red.
    2. Click an exit on a different junction.
    3. Press the Link Exits button that appears in the header.

    Links are bidirectional. Vehicles can traverse them in either direction. They are rendered as Bézier curves with solid and dashed lane markings matching lane configuration.

    Press the Confirm button to lock your layout, then press Play to start the simulation.

    • Vehicles spawn at entry exits based on the global spawn rate (default 0.5 vehicles/second).
    • Demand is distributed across available routes and balanced by per-entry spawn queues.
    • Per-exit spawn rate overrides are supported.

    Vehicles follow the Intelligent Driver Model (IDM) with:

    • Smooth acceleration and deceleration curves per car class.
    • Leader-follower spacing with configurable bumper gap and time headway.
    • Comfort braking and emergency braking thresholds.
    • Speed adaptation near stop lines and junctions.
    Button Action
    Play Start simulation
    Pause Pause (vehicles freeze in place)
    Stop Halt and reset simulation
    Parameter Default Description
    Green Time 8 s Duration of green phase per arm
    Amber Time 1 s Warning phase before red
    Red-Amber Time 1 s Transition phase before green
    All-Red Time 2 s Safety gap between phase changes
    Parameter Default Description
    Min Gap 2 m Minimum distance on ring for safe entry
    Min Time Gap 1.5 s Time since last vehicle exited ring
    Safe Entry Distance 20 m Look-ahead distance for gap detection
    Entry Timeout 1.0 s Force entry after this queue wait
    Min Angular Separation 30° Vehicles must be spaced at least this far apart on the ring

    Real-time statistics are available in the Stats panel and the popout statistics window.

    Metric Description
    Approaching Vehicles on approach segments
    Waiting Vehicles stopped at stop lines
    Inside Vehicles currently crossing the junction
    Exiting Vehicles on exit segments
    Entered / Exited Cumulative flow counters
    Avg Wait Time Mean delay per vehicle (seconds)
    Max Wait Time Longest individual delay recorded
    Max Queue Length Peak queue depth observed
    Throughput Vehicles per minute
    DoS Degree of Saturation - demand ÷ capacity ratio
    PRC Practical Reserve Capacity - how much additional traffic the junction can handle (%)
    MMQ Mean Maximum Queue - average of per-arm peak queues
    LOS Level of Service - HCM-based A–F grade
    Grade Signalised (s) Roundabout (s) Interpretation
    A ≤ 10 ≤ 10 Free flow
    B ≤ 20 ≤ 15 Stable flow
    C ≤ 35 ≤ 25 Stable, acceptable delays
    D ≤ 55 ≤ 35 Approaching instability
    E ≤ 80 ≤ 50 Unstable flow
    F > 80 > 50 Forced / breakdown

    Throughput, Avg Wait, Max Queue, PRC, and MMQ are also computed network-wide across all junctions.

    Click the Report button (available after stopping a simulation that has recorded data) to generate a 3-page landscape A4 PDF:

    Page Content
    1 - Junction Diagram High-resolution rendered diagram of your layout with numbered exits, lane markings, link curves, and a colour-coded legend.
    2 - Configuration Global settings, per-object exit/lane tables, spawning & motion parameters, controller timings, and car class weights. Overflows to additional pages if needed.
    3 - Simulation Summary Overview tiles (spawned, completed, elapsed, avg speed, avg travel time), all-junction aggregate table, and per-junction breakdown with DoS, PRC, MMQ, and LOS pills. Overflows to additional pages for large networks.

    Click the Download button to export your junction layout and simulation configuration as a .jme JSON file.

    The save file contains:

    • All junction objects (type, position, exit configuration)
    • All links between exits
    • Full simulation config (spawn rates, vehicle physics, controller timings, car class overrides)

    Click the Upload button and select a .jme file. The current layout is replaced with the saved configuration. You can immediately confirm and run a simulation.

    JME supports real-time peer-to-peer collaboration via WebRTC (PeerJS).

    Note: P2P works out of the box over a local network (LAN). For connections across the internet, you will need to configure port forwarding and set up a TURN server and PeerJS signalling server.

    1. Open the Session dropdown.
    2. Click Create Host - a 6-digit connection code is generated.
    3. Share the code with others.
    1. Open the Session dropdown.
    2. Enter the host's 6-digit code and click Join.
    3. The host's junction layout and simulation config are synced automatically.
    • The host controls the layout and simulation (start, pause, stop).
    • Clients receive real-time updates and can observe but not modify the configuration.
    • Connection status and latency are shown in the Session panel.
    • Disconnect at any time using the exit button.

    Click the ? Tutorial button to start an interactive 21-step guided walkthrough that covers:

    1. Switching to Build mode
    2. Adding an intersection and a roundabout
    3. Positioning objects by dragging
    4. Configuring exits and lanes
    5. Linking two junctions together
    6. Confirming the layout
    7. Adjusting simulation parameters
    8. Running the simulation
    9. Stopping the simulation
    10. Downloading a save file
    11. Generating a PDF report

    Each step highlights the relevant UI element and auto-advances when you complete the required action. Starting the tutorial resets the workspace to a clean state.

    Control Action
    Left-click drag Orbit around scene
    Right-click drag Pan
    Scroll wheel Zoom in/out
    Double-click junction Centre and zoom to that object
    Click a vehicle (during sim) Follow in first-person view
    Backspace Exit first-person view
    Control Action
    Scroll wheel Zoom (height adjustment)
    Left-click drag on object Move junction
    Double-click object Open config panel
    Click exit arm Select exit (for linking)

    The default camera position is an isometric view at (20, 35, 20) with a 60° field of view.

    Vehicles are rendered as 3D models with 12 body types and 7 colour variants. Each class has distinct physical characteristics:

    Class Length (m) Speed Accel Default Weight
    Normal 1.82 1.00× 1.00× 25
    Hatchback 1.81 1.00× 1.00× 20
    Coupe 1.99 1.10× 1.15× 10
    Station 2.10 1.00× 0.95× 10
    MPV 2.00 0.95× 0.90× 8
    Pickup 1.97 0.95× 0.85× 6
    Pickup (Small) 1.92 0.95× 0.90× 6
    Minibus 2.16 0.90× 0.75× 5
    Micro 1.42 0.85× 1.05× 5
    Microcargo 1.82 0.80× 0.90× 3
    Microtransport 1.82 0.80× 0.85× 3
    Van 2.16 0.85× 0.70× 3

    Weight determines spawn probability - higher weight = more common. All classes can be individually enabled/disabled and their speed, acceleration, deceleration, and weight overridden in the Sim Config panel.

    Colours: Blue, Citrus, Green, Orange, Red, Silver, Violet (randomly assigned at spawn).

    All parameters are adjustable in the Sim Config dropdown.

    Parameter Default Range Description
    Spawn Rate 0.5 v/s 0–5 Vehicles per second per entry
    Max Vehicles 100 10–500 Simultaneous vehicle limit
    Max Spawn Queue 25 - Per-entry demand cap
    Max Spawn Attempts/Frame 20 - Spawn loop limit
    Parameter Default Range Description
    Preferred Speed 10 m/s 1–30 Target cruising speed
    Max Acceleration 4 m/s² 0.5–15 Acceleration cap
    Max Deceleration 8 m/s² 0.5–15 Emergency braking cap
    Comfort Deceleration 4 m/s² - Preferred smooth braking
    Parameter Default Range Description
    Min Bumper Gap 0.5 m 0–5 Safety distance between vehicles
    Time Headway 0.5 s 0.1–5 Speed-proportional following distance
    Stop Line Offset 0.01 m 0–2 Where vehicles stop relative to lines
    Parameter Default Description
    Sim Seed "default" String seed for deterministic, reproducible simulations
    • Next.js 16 (App Router, Turbopack)
    • React 19 + TypeScript 5
    • Three.js + React Three Fiber + Drei (3D rendering)
    • PeerJS (WebRTC peer-to-peer networking)
    • jsPDF (PDF report generation)
    • Tailwind CSS 4 + shadcn/ui (interface components)
    • Lucide React (icons)

    Settings

    Member Visibility

    On This Page

    JME - Junction Modeller ExpandedNext.jsThree.jsTypeScriptPeerJSDocumentation