> ## Documentation Index
> Fetch the complete documentation index at: https://dcc-5ccd5152.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Using Interlockings to Coordinate at Busy Track Sections

> Occupy a BigFred interlocking to coordinate with drivers, use radio chat, play station announcements, and manage movements through busy junctions safely.

An interlocking in BigFred is a virtual coordination zone that represents a real section of controlled track — a station throat, a junction, a crossing, or any other area where multiple movements must be managed safely. Your layout admin creates and names each interlocking; once they're configured, every operator on the layout can see them from the home dashboard and, if they hold the signalman role, claim one to manage traffic through it.

## Why use an interlocking?

Busy junctions and station approach tracks are where collisions happen on a model railroad. An interlocking gives the operator controlling that area — the signalman — a single place to see who is approaching, talk to drivers over radio chat, issue structured announcements (entry permitted, departure cleared, stop immediately), and coordinate movements before anything moves through the danger zone.

## Joining an interlocking

Only operators with the **signalman** role can occupy an interlocking. If your admin has granted you that role, you'll see an **Occupy** button on the interlocking's page. If you do not yet have the role, contact your layout admin.

<Steps>
  <Step title="Find the interlocking on the dashboard">
    Open BigFred and go to the **Home** page. The lower section of the dashboard shows a table of all interlockings configured for your layout, along with their location and current occupant (if any).
  </Step>

  <Step title="Open the interlocking page">
    Click any row in the interlockings table to open that interlocking's page. The page header shows the interlocking's name, its optional track location, and a badge indicating whether it is currently vacant or occupied.
  </Step>

  <Step title="Click Occupy">
    If the interlocking is vacant and you hold the signalman role, click the **Occupy** button. You are now the occupant — the badge updates to show your name and the three working panels appear below the header.
  </Step>

  <Step title="Work the interlocking">
    Use the chat, roster, and announcements panels to coordinate movements. See the panel descriptions below for details on each.
  </Step>

  <Step title="Click Leave when done">
    When traffic through the area is clear and you are ready to hand it back, click the **Leave** button. The interlocking returns to a vacant state and other signalmen can occupy it.
  </Step>
</Steps>

<Note>
  If you try to navigate away from the interlocking page while you are still occupying it, BigFred intercepts the navigation and asks you to confirm. Confirming will automatically call Leave before proceeding. This prevents accidentally leaving an interlocking "open" with no one staffing it.
</Note>

If another signalman is already occupying the interlocking when you click Occupy, BigFred asks you to confirm before displacing them. Only do this if you have coordinated with that operator in advance — displacing someone mid-session will interrupt their work.

## The three working panels

Once you occupy an interlocking, three panels appear on the page. On a wide screen they display side-by-side; on a narrow screen (phone) they are arranged as tabs you can switch between.

<CardGroup cols={3}>
  <Card title="Chat" icon="radio">
    **Radio Chat** — a scrollable log of all radio messages sent between drivers and the interlocking. New messages trigger an audio chime and an alert banner so you don't miss anything even when the panel is out of view. An unread-count badge appears on the Chat tab when new messages arrive while you're looking at a different panel.
  </Card>

  <Card title="Roster" icon="list">
    **Roster** — a live table of all vehicles and trains registered on the layout, showing their owner and whether they are currently in motion. Use the search box to filter by name or operator. From each row you can open radio chat directed at that vehicle's operator, issue an emergency stop, or request a throttle takeover.
  </Card>

  <Card title="Announcements" icon="volume-high">
    **Train Announcements** — a set of pre-recorded public-address audio clips. Click any entry to play the sound locally on your device. A speaker icon lights up next to the clip that is currently playing.
  </Card>
</CardGroup>

## Making a train announcement

Train announcements are distinct from radio chat: they are pre-recorded audio clips played locally on your device to simulate station PA messages. The available clips are built into BigFred and include station departure announcements such as **Track 1 Freight**, **Departure Głuszyca**, **Departure Wrocław**, and **Departure Warszawa Centralna**. To play an announcement:

1. Open the **Announcements** panel (or tab on narrow screens).
2. Click the announcement you want to play. BigFred immediately plays the audio clip on your device.
3. Clicking the same entry while it is already playing stops and restarts it. Clicking a different entry stops the current clip and starts the new one.

## Using radio chat

The **Chat** panel shows the history of radio-style phrase messages sent to or from this interlocking. Messages fade slightly over time to help you focus on recent traffic.

To send a message, click the **Reply** button (↩) on any message line from another operator. A phrase picker dialog opens — choose the appropriate radio phrase, optionally add a short free-text note, and send. Your reply is addressed directly to that operator and also visible to everyone in the interlocking chat.

BigFred plays a radio chime sound whenever a new inbound message arrives for your interlocking. If the Chat panel is not visible (you're on another tab), an unread-message count badge accumulates until you switch back.

## Sound notifications

BigFred plays audio feedback for interlocking events:

| Event                           | Sound           |
| ------------------------------- | --------------- |
| Inbound radio message received  | Radio chime     |
| Train announcement clip playing | The clip itself |

Your browser must allow audio playback on the BigFred page for sounds to work. If you hear nothing, check that your browser has not blocked autoplay for this site.

## Leaving an interlocking

Click **Leave** in the interlocking header at any time to release occupancy. If you navigate away without clicking Leave — by pressing the back button, closing the tab, or clicking a navigation link — BigFred's navigation guard dialog will prompt you to confirm. Confirming both calls Leave and then completes the navigation. Cancelling returns you to the interlocking page with your session intact.