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RDT

How the RDT (traffic regulator) works

The RDT is the system that tries to keep trains from crushing the headway. If you drive, you want to read the platform panel, know when it holds you, what a line STOP means, and why the SIU talks about altered frequency.

10 min read

What the RDT is

RDT stands for traffic regulator (Catalan: Regulació de Trànsit). In MetroSim it is not a separate character: it is service logic that watches the train carousel, the planned headway and, if needed, holds you at the platform so the next train does not catch you.

You meet it on the official line (L2, L3 and L11) and in rooms. As a player you feel it in the cab, on the platform and on the SIU: warnings, starter signals and holds.

Headway and regularity

Each line has a service headway (for example about 5 minutes on L11 with two trains). The RDT checks whether you are early against that rhythm. If you arrive “too soon”, it can ask you to wait with doors open before leaving.

When service is clean, trains space themselves. If someone runs early, the RDT corrects it at the platform. You do not need to calculate anything: just respect a hold when the cab or the starter signal shows it.

  • Running early → more chance of a platform hold.
  • On time → normal departure once doors close and you have a clear road.
  • Running late → the RDT does not punish lateness; it tries not to hold you extra.

How to read the RDT panel

On the platform (especially on L11) you will see amber three-window LED RDT boxes. Top: early (A) or late (R) offset and regularity. Middle: the march order. Bottom: the hold countdown or STOP. Read them before you leave.

Each icon below is a typical panel face. The platform SIU is another clue: next-train countdown and an altered-frequency warning if there is a STOP.

  • 1:30 early. Wait that countdown at the platform with doors open. Downward arrows mean slow down.

  • 0:45 late. You can leave once doors close and you have a clear road. Upward arrows mean you can catch up.

  • Terminus H: held at the terminal. The bottom clock is what remains after the cab change.

  • Line STOP: (S) and STOP in steady amber LED, no blink. No train leaves the platform until it clears.

  • RDT inhibited in that session: nobody is held for regulation. Signals and ATP still apply.

  • The hold clock (when there is no STOP) blinks for the last ~10 s: the wait is about to end.

Line STOP

Line STOP is the RDT’s strongest order. When it is on, the message is clear: do not leave the platform. AI trains finish the station they are in, open doors and stay. If you are driving, do the same: finish the stop and wait until STOP is cleared.

On the RDT box you will see (S) in the middle and STOP below, in steady amber LED like the other orders. In the cab you usually get a STOP warning. On the platform SIU the altered-frequency text appears: the headway is not normal.

Platform hold (without STOP)

Even without a line STOP, the RDT can hold you for a few seconds or a few minutes if you are early. Same idea as a real metro: do not leave if you would break the headway.

During a hold the train stays at the platform with doors open. When the wait ends and you have a clear road, close and leave as usual.

  • A hold is not forever: as soon as the headway allows it, you can leave.
  • If the line headway is 5 minutes, the hold usually will not ask for more than that rhythm.

What you may notice in the cab

AI trains respect regulation when the RDT is on. For you, depending on the session, holds can feel different:

  • Warning only: you see the hold in the cab, but the starter signal does not force it. The most common way to learn.
  • Hard hold: the starter stays red for the wait. Wait until it clears.
  • No player regulation: sometimes it does not hold you even if AI is still regulated. If you see no warnings, drive normally.

Where you notice it in-game

In the cab: wait or STOP messages, a red starter while you are held, and a train that should not leave until the wait ends.

On the platform: the SIU shows altered frequency under a line STOP, and RDT boxes (if present) show march orders — arrows, H, (S) — with the hold clock or STOP below, all in amber LED.

On the MetroSim site, each line status card shows the live headway: how many minutes usually sit between trains with the current service.

Practical tips for drivers

Drive with the headway in mind: if the line is on 5 minutes, there is no prize for flying between stops; the RDT will give that time back at the platform.

  • Read the SIU on arrival: altered frequency may mean a STOP — wait.
  • Do not force a red starter during a hold — service will thank you.
  • At a terminus, cab changing and dwell still apply; the RDT adds to that ritual, it does not replace it.
  • If unsure, stay at the platform a few extra seconds — cheaper than skipping the hold.