Railways Use of the 24 Hour Clock

[AdamWW]

TfW auto announcements use it alongside the 24 hour equivalent in English.

Not just the 12 hour clock in Welsh, but (despite knowing very little Welsh) I'm pretty sure the TfW announcements use the form "5 minutes to 5" rather than 4:55 never mind 16:55.

 

[Western 52]

Not just the 12 hour clock in Welsh, but (despite knowing very little Welsh) I'm pretty sure the TfW announcements use the form "5 minutes to 5" rather than 4:55 never mind 16:55.

Yes that's the form they use.

 

[Gaelan]

A presumably oft-asked question.... Be right in saying that the public timetable never normally shows an 00:00 (or 24:00) arrival or departure time? Or, is that not necessarily the case?

Yes. Among other reasons, CIF (the file format used for exchanging GB timetables) uses 0000 to represent the absence of a time - a train booked to pass a station, or pick up/set down only, will have one or both public times recorded as 0000. This means it is impossible, at a technical level, for a train to be publicly scheduled for 00:00. I’m less sure, but I believe WTT times of 0000 are impossible, but 0000H (ie 30 seconds past midnight) is permissible.

Presumably this decision was made in response to an earlier convention, I believe to avoid any confusion as to “which midnight” 00:00 referred to.

 

[norbitonflyer]

To take this a bit further how do timetables cope with that bi-annual farce of clocks change, clocks forward (at least you miss an hour) and clocks back, the hour repeats. Not sure how many trains will be running at this time, probably sleepers and I know TPE North used to be pretty much 24 hour on the core route

When i frequented London's night buses, the practice was to run them all night as if the clocks hadn't changed - this would mean a bit of a gap between the last nighth bus and the first day bus on Sunday morning when the clocks went back.

However, way back then, there were very few night buses on Saturday night anyway - they were intended more for people working nights in the markets and newspapers (hence so many of them running along Fleet Street) rather than revellers.

== Doublepost prevention - post automatically merged: 25 Jul 2025 ==

When the 12 hour clock was in use, I understand am times were shown in bold type and pm times in lighter type. The switch to the 24 hour clock meant all times were shown in bold, with lighter type iused for connections. Much to the confusion of my father, who couldn't get his head round this

He was 35 when the change happened so not comletely set in his ways, but coincidentally he passed his driving test that year, so became much less reliant on trains, which may account for his lack of familiarity with the modern format in later years

 

[AdamWW]

When i frequented London's night buses, the practice was to run them all night as if the clocks hadn't changed - this would mean a bit of a gap between the last nighth bus and the first day bus on Sunday morning when the clocks went back.

However, way back then, there were very few night buses on Saturday night anyway - they were intended more for people working nights in the markets and newspapers (hence so many of them running along Fleet Street) rather than revellers.

== Doublepost prevention - post automatically merged: 25 Jul 2025 ==

When the 12 hour clock was in use, I understand am times were shown in bold type and pm times in lighter type. The switch to the 24 hour clock meant all times were shown in bold, with lighter type iused for connections. Much to the confusion of my father, who couldn't get his head round this

He was 35 when the change happened so not comletely set in his ways, but coincidentally he passed his driving test that year, so became much less reliant on trains, which may account for his lack of familiarity with the modern format in later years

I think Merseyrail stuck with (or re-introduced?) the 12 hour clock when everything else on the railways used the 24 hour clock.

 

[Gaelan]

When the 12 hour clock was in use, I understand am times were shown in bold type and pm times in lighter type.

American timetables retain this convention, albeit the other way around (bold for pm).

 

[Tester]

American timetables retain this convention, albeit the other way around (bold for pm).

Indeed - even for airlines!

 

[Merle Haggard]

In the days of B.R. using 12 hour times in documents, handwritten and typed, the two times were differentiated by showing, for example, '11.00' vs '11/00'. Working timetables had 'a.m.' or 'p.m.' at the top of each column (or down the column, if the train crossed the mid-day or mid-night divide) so the ambiguity didn't arise there.

 

[U-Bahnfreund]

Not GB, and not railway, but.....

In Japan it is not unusual to see opening hours for bars etc. 'going round the clock' - so somewhere open from 1730 to 0130 will show 1730-2530.

I have never seen this anywhere else.

At my railway in Germany we do use times with 25:00, 26:00, 27:00, 28:00 internally, as a train is assigned an operational day which doesn't necessarily have to be the same as the calendar day. Usually around 3 am it changes on days that have through night service, also tied to when the diagram of a train comes from or goes to the depot.

When the 12 hour clock was in use, I understand am times were shown in bold type and pm times in lighter type. The switch to the 24 hour clock meant all times were shown in bold, with lighter type iused for connections. Much to the confusion of my father, who couldn't get his head round this

Germany changed to the 24 hour clock much earlier but very old timetables (like late 1800s, early 1900s) used the 12 hour clock. Differentiated also with bold/light type or underlined/not underlined minutes, but confusingly not am/pm but rather day and night, so all times between 6 pm and 5:59 am were different from 6 am to 5:59 pm.

 

[AdamWW]

Germany changed to the 24 hour clock much earlier but very old timetables (like late 1800s, early 1900s) used the 12 hour clock. Differentiated also with bold/light type or underlined/not underlined minutes, but confusingly not am/pm but rather day and night, so all times between 6 pm and 5:59 am were different from 6 am to 5:59 pm.

I seem to recall Bradshaws did something similar.

 

[etr221]

Not GB, and not railway, but.....

In Japan it is not unusual to see opening hours for bars etc. 'going round the clock' - so somewhere open from 1730 to 0130 will show 1730-2530.

I have never seen this anywhere else.

I came across a reference to the Madrid Tramways (IIRC) continue to increment times until the end of their traffic day at circa 26:30.

It does avid the confusion of the last train being before the first train every day...

== Doublepost prevention - post automatically merged: 25 Jul 2025 ==

AIUI summer time came into use during WW1, so timetabling had to accommodate seasonal clock changes long before the 24 hour clock was adopted.

Summer time was first introduced (throughout the UK) on 21st May 1916. At that point, Ireland was still on Dublin (Mean) Time: the really interesting clock change was on 1st October 1916, when Ireland changed to Greenwich based time, and at 3:00am (BST) - that was the defined operative time for the change, AIUI - the Irish had to change their clocks from 2:34:39 (Dublin Summer Time?) to 2:00 am (GMT)...

And then in WW2 we had double summer time (GMT+2 hours); culminating in (IRRC) 1948 when we went from GMT in winter, first to BST (GMT+1) and then to BDST (GMT+2) for high summer; and then in the autumn we went back to GMT in two stages... (so total of four clock changes that year)

== Doublepost prevention - post automatically merged: 25 Jul 2025 ==

The British Army adopted the 24 hour clock on 1st October 1918, as part of the standardisation of practices amongst the allies on the Western Front inspired by Generalissimo Foch.

The first country to introduce the 24-hour clock as standard was Italy, in 1893 - the French followed in 1912: a just post WW1 British government report (on possible UK change to 24 hour clock) noted that for the peasantry, it hadn't made any difference...