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The signalman is the operator responsible for controlling train movements through a specific interlocking — a junction, station throat, or any other controlled area of the layout. Unlike drivers, who each work independently with their own locomotive, a signalman focuses on the big picture: who is approaching, who has clearance to move, and whether anything needs to stop immediately. The role is optional; layouts without a signalman simply use the interlocking pages as a coordination aid without gated entry control.

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The signalman role in BigFred

Each interlocking can have at most one occupant at a time, and only an operator who holds the signalman role can occupy one. The role is a property of your user account on a given layout — it is not per-interlocking. This means once you are granted the signalman role, you can occupy any interlocking on that layout, but you can only staff one at a time. Drivers without the signalman role can still view any interlocking page to see who is staffing it and watch the occupancy status, but the Occupy button will not appear for them.

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Becoming the signalman

There are two ways the signalman role can be assigned to you:
  • Admin promotes you from the dashboard — an operator with admin rights can click the promote-to-signalman icon next to your name in the Online Users table on the home dashboard. This grants you the signalman role permanently for that layout (until explicitly revoked).
  • You request the role yourself from the dashboard — if you are not already an admin, you can click the same promote icon next to another driver’s name, but you will be prompted for the layout’s admin PIN to authorize the change.
1

Open the Home dashboard

Navigate to the Home page. The Online Users table at the top shows everyone currently connected to the layout.
2

Locate the target operator

Find the row for the driver you want to promote (or your own account if an admin is doing this). Only users currently holding the driver role will show the promote-to-signalman button.
3

Click the promote icon

Click the engineering/hard-hat icon in the Actions column for that user. If you are an admin, the role change happens immediately. If you are not an admin, a PIN dialog opens.
4

Enter the admin PIN (if required)

Type the layout’s admin PIN and confirm. BigFred requests a temporary two-minute admin elevation (sudo) on your behalf, then applies the role grant. The elevation expires automatically — you do not stay as admin after this action.
5

Occupy an interlocking

With the signalman role active, open any interlocking from the dashboard and click Occupy to begin staffing it.

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Stepping down from the role

To relinquish the signalman role, an admin (or another operator using a PIN elevation) clicks the demote icon — the train icon — next to your name in the Online Users table. This returns your account to the driver role. If you are currently occupying an interlocking, leave it first — the role removal does not automatically end an active session.

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What the signalman can do

Once you are occupying an interlocking, you have full access to all three working panels. Your key capabilities are:
From the Chat panel, click the reply button on any incoming message to open the phrase picker. Select the appropriate radio phrase — such as Entry Permitted, Departure Cleared, Route Set, or Stop Immediately — and optionally add a short free-text note. The message is sent directly to that driver and also logged in the interlocking chat for all occupants to see.You can also initiate a message to any operator directly from the Roster panel: click the radio antenna icon on the vehicle or train row you want to address. This opens the same phrase picker pre-addressed to that vehicle’s owner.
The Roster panel lists every vehicle and train registered on the layout. An In Motion chip appears next to any consist that is currently moving (non-zero speed on the DCC bus). Use the search box to filter by operator name or vehicle name. This gives you a real-time view of what is happening across the layout even when operators aren’t calling in.
In the Roster panel, click the stop icon (🛑) on any vehicle or train row to issue an emergency stop targeted at that consist. BigFred asks you to confirm before sending the command. Use this only when a vehicle must halt immediately and the driver is not responding to radio calls.
Open the Announcements panel and click any entry to play the pre-recorded PA clip on your device. See the interlocking overview for full details.

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Throttle takeover

In exceptional situations — for example, a driver is unresponsive and their locomotive is moving toward a conflict — you can request a brief takeover of their throttle to bring the train safely to a halt.
A throttle takeover is an emergency tool. It interrupts the driver’s session and assumes control of their locomotive without their prior agreement. Use it only when radio calls have gone unanswered and safety demands it. The signalman must bring the locomotive to a full stop (speed 0) before the takeover can be released; the takeover window is time-limited and control will revert to the driver automatically when the lease expires.
1

Locate the vehicle in the Roster panel

Find the operator’s vehicle or train in the Roster panel. Vehicles currently in motion show an In Motion chip.
2

Click the takeover icon

Click the swap/arrows icon (⇄) on that row. BigFred immediately sends a takeover request to the driver’s session and opens a Waiting for Takeover dialog on your screen showing a countdown.
3

Driver sees the request overlay

On the driver’s screen, a takeover request dialog appears showing a 15-second countdown. The driver can click Reject to immediately refuse the request. If they do not reject before the timer reaches zero, the takeover is granted automatically.
4

Takeover is granted

Once granted (by timer expiry or when the driver does not reject), your waiting dialog closes and a full Throttle Cockpit overlay opens on your screen. A countdown chip in the overlay header shows the remaining lease time.
5

Bring the train to a stop and release

Use the cockpit to reduce speed to zero. The Release button in the overlay header becomes active only when speed reaches 0. Click it to end the takeover and return control to the driver.
If the driver actively rejects the takeover request, your waiting dialog closes and a brief warning appears. In that case, use radio chat to communicate with the driver before trying again. You can also cancel a pending takeover request yourself (before it is granted) by clicking Cancel in your waiting dialog.

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Sudo elevation and PIN prompts

Some actions in BigFred that affect other users’ roles require temporary admin rights. When you are not already an admin and you try to promote or demote another operator, BigFred shows a PIN dialog and requests a two-minute sudo elevation using the layout’s admin PIN.
  • The elevation lasts exactly two minutes from the moment it is granted.
  • It is scoped to the specific action — granting or revoking the signalman role — and expires automatically.
  • You do not retain admin access after the elevation window closes.
  • Your layout admin sets the admin PIN in the layout settings. Ask your admin if you do not know the PIN for your layout.