Signaller communication: phonetic alphabet, numbers and repeat-back

Most of a signaller's safety-critical decisions reach the outside world as a sentence spoken down a phone or radio. A driver is told to pass a signal at danger. A track worker is given a line. A line is handed back. If the words are misheard, the panel or the levers can be perfect and the outcome still goes wrong.

That is why the law treats talking as part of the job's safety. The Railways and Other Guided Transport Systems (Safety) Regulations 2006 list “receiving and relaying of communications” as a safety critical task alongside signalling itself. RSSB, the rail industry's safety body, says research has found poor safety critical communication to be a contributing factor in one in five accidents and 17% of SPADs (signals passed at danger).

You learn the formal rules in signaller training, after an offer. Network Rail's training page lists safety-critical communication as one of the course's modules. Nobody expects you to know them before you apply. But they are short, they are public, and knowing how signallers are expected to speak gives you something concrete to draw on at the video interview and the assessment day.

The rules in plain English

The communication rules for signallers are in section 5 of Rule Book module G1, published by RSSB. The same procedure appears in the track workers' handbook (Handbook 1), which was still carrying it in its December 2024 issue. Paraphrased, the rules are as follows.

1. Start by establishing who, where and what

Before anything else, make sure you are talking to the right person. On a phone or radio, give your exact location, your name and your employer, and say what task you are doing. If it might be needed, say how you can be contacted. A driver ringing from a signal post telephone does this the other way round: which signal, which train, who they are.

2. One person leads the conversation

Every safety-critical conversation has someone with lead responsibility, the person who steers it and makes sure it ends with a shared understanding. The Rule Book's table puts the signaller in the lead when talking to anyone except the electrical control operator. So on a call with a driver, a track worker or a person in charge of a possession, the signaller leads. Where it is unclear, the person who started the call leads.

3. Numbers are said one digit at a time

The Rule Book's own example is that 8107 is said “eight, one, zero, seven”, not “eighty-one oh seven”. There are stated exceptions, such as giving the time or referring to a Rule Book module or handbook.

4. Letters are said phonetically

The phonetic alphabet must be used to identify letters, to spell words and place names that are hard to say or easy to mishear, when there is interference on the radio or phone, when quoting signal or points identities, and when quoting train descriptions (the four-character reporting numbers such as 1F52).

5. Messages are repeated back

If you receive a message, you must repeat it back so the other person knows you understood it correctly. If you send one, you get the other person to repeat it back to you. A message is not confirmed until the repeat-back matches.

6. Use the standard phrases

• “This is an emergency call”: the message needs immediate action to prevent death, serious injury or damage.
• “Repeat back”: repeat all of the message back to me.
• “Correction”: I have made a mistake and will now correct what I just said.
• “Over” and “Out”: used on radios where only one person can be heard at a time. “Over” means I have finished and expect a reply. “Out” means I have finished and no reply is expected.

7. “Line blocked”, never “not clear”

A line that is obstructed is always described as line blocked. “Not clear” is banned for this purpose. Over a crackly radio, “not clear” can be heard as “all clear”.

8. Speak so you can be understood

The practical advice in the same section is to keep the mouthpiece close to your mouth, talk slightly slower than normal with a natural rhythm, use your normal volume, avoid “um” and “er”, and use clear sentences. RSSB sums it up as ABCP: accurate, brief, clear, professional. Network Rail's training page uses the same four words.

The phonetic alphabet

This is the standard international alphabet, as printed in the Rule Book (note the railway spelling “whisky”):

• A alpha · B bravo · C charlie · D delta · E echo · F foxtrot · G golf
• H hotel · I india · J juliet · K kilo · L lima · M mike · N november
• O oscar · P papa · Q quebec · R romeo · S sierra · T tango · U uniform
• V victor · W whisky · X x-ray · Y yankee · Z zulu

Put that together with the digit rule and railway identities come out like this:

• Train 1F52 is “one foxtrot five two”.
• Signal WM217 is “whisky mike two one seven”.
• Points 2047 are “points two zero four seven”.

A worked example: the same call done badly and done well

This is an illustration we wrote to show the rules in use, with made-up train and signal numbers. It is not an official script.

Badly: “Hi, it's the signaller. Your 1F52 can go past WM217, it's fine, I've got the line blocked ahead — just watch yourself. Cheers.”

The signaller never confirmed who they were talking to or where. The train and signal identities were run together and could be misheard. “Got the line blocked” does not say which line. “Watch yourself” is not an instruction. And nobody repeated anything back, so neither side knows what the other understood.

Well:

• Signaller: “Is that the driver of one foxtrot five two?” Driver confirms and gives their name.
• Signaller: “This is the signaller at [box name]. You are standing at signal whisky mike two one seven, showing a stop aspect. I am authorising you to pass that signal at danger. Repeat back.”
• Driver repeats the whole message, including the signal number.
• Signaller confirms the repeat-back is correct and gives any further instructions, again in full and again repeated back.

The real instructions for passing a signal at danger contain more than this, and you learn them in training. The point here is the structure: identify, state, repeat back, confirm.

What happens when it goes wrong

The Rail Accident Investigation Branch (RAIB) publishes short safety digests on near misses. Two are worth reading because both turn on what a driver and a signaller each understood.

Stafford, 2 March 2018. A driver stopped at Stafford with a brake fault and asked the signaller to block the adjacent lines so he could get down and work on his train. While he was on the track, he saw a train approaching on the adjacent northbound line. He had to lie down beside his train to avoid being struck. RAIB's safety message was that signallers should tell drivers the names of the lines that are blocked and the lines trains are still running on. Drivers are not normally expected to know the numbers of every signal and set of points, so they may not recognise a line from those numbers. Drivers, in turn, should check the status of each adjacent line if they are unsure.

Near Nottingham, 1 January 2024. A freight train was stopped after a hot axlebox detector activated, and the driver got down to examine it. A passenger train then came along the adjacent line while he was standing between the rails in its path. The passenger train's driver braked and sounded the horn, and he got clear. RAIB found the freight driver and the signallers had not reached a clear understanding of how the examination would be done. The driver had changed his method for the second check without telling the signaller, and on that second call the signaller did not ask whether the adjacent line needed to stay blocked. Among RAIB's key messages was the importance of following correct safety critical communication protocols.

Neither case involved anyone being careless in the everyday sense. Both involved two people leaving a conversation with different pictures in their heads, which is exactly what the procedure is built to prevent.

Where this helps during selection

Network Rail does not publish its marking criteria, and nothing it says suggests you will be tested on the phonetic alphabet. What it does say about the current process is enough to make this worth an hour of your time.

• Video interview. Network Rail says it “measures the behaviours required to be a Signaller”. Its signaller page describes the job as including “communicating with train drivers, controllers and maintenance teams”, and its FAQs list being a strong communicator among the skills that make a good signaller. An example where you made sure an instruction was understood, by checking it back rather than assuming, is the kind of evidence this stage is built to hear. Our signaller interview questions guide covers how to structure it.
• Assessment day. Network Rail describes an interview and “simulated activities relevant to Signalling”. It does not publish what those activities are. If any of them involve passing or receiving information, the habits above (state it in full, use digits one at a time, ask for a repeat-back) are the natural way to show care. See the assessment centre guide for what applicants report.
• The job simulation. Scenario questions often turn on a misheard or unconfirmed message. The principle in our job simulation guide, confirm rather than assume, is the repeat-back rule as a decision. Try it on the free job simulation sample.
• The medical. Network Rail says any speech impediment will be assessed to confirm you can communicate clearly in time-critical and safety-critical situations. Every candidate is assessed individually. See the signaller medical.

A ten-minute practice drill

None of this needs equipment. A few short sessions are enough to make it automatic.

1. Learn the alphabet cold. Read car number plates aloud phonetically as you walk past them until you no longer hesitate on any letter.
2. Read codes, digit by digit. Write ten made-up train descriptions and signal numbers (2C17, 5Z90, TS402) and say them aloud the railway way. Mumbling “twenty-one” instead of “two one” is the habit to break.
3. Do repeat-backs with someone. Have a friend read you a three-part message (a train, a signal, an instruction) over the phone. Repeat it back word for word, then swap. You will notice how often you paraphrase without meaning to.
4. Practise “correction”. Deliberately say a wrong digit, then say “correction” and give the right one, instead of “sorry, I mean”.
5. Name things, do not point at them. When you describe a route or a line to someone, use names they would recognise, not internal numbers. This is the Stafford lesson.

Reading identities accurately under time pressure is close kin to the fast, accurate checking in the online assessment. If you want to practise that side, the concentration practice and multi-tasking practice are original exercises built for the same abilities. They are not copies of Network Rail's tests. For any railway word above you have not met, see signalling terms explained.