Speed measurement

[abr2024]

Can the track report overspeed incidents?

Obviously aware of TPWS but that isn’t what I mean.

Say for example, a train was supposed to go over a junction at 30mph, but the driver did over this in error, would the track be able to alert the signaller and/or NR of the incident?

 

[12LDA28C]

Can the track report overspeed incidents?

Obviously aware of TPWS but that isn’t what I mean.

Say for example, a train was supposed to go over a junction at 30mph, but the driver did over this in error, would the track be able to alert the signaller and/or NR of the incident?

In a word - no.

 

[james_the_xv]

Class 390s (and Class 221s when with Avanti) run something called TASS (Tilt Authorisation and Speed Supervision), but I don't believe it alerts NR of any overspeed.

 

[PupCuff]

Can the track report overspeed incidents?

Obviously aware of TPWS but that isn’t what I mean.

Say for example, a train was supposed to go over a junction at 30mph, but the driver did over this in error, would the track be able to alert the signaller and/or NR of the incident?

Yes, but I don't know how widespread it is. There are a couple of locations on my patch where NR monitor train speed via track circuit/axle counter section occupancy times and ping across an email to let the TOC know if there's been a possible overspeed event to follow up on. Given I see very very few, I suspect it is confined to just high risk locations.

 

[hexagon789]

Can the track report overspeed incidents?

Obviously aware of TPWS but that isn’t what I mean.

Say for example, a train was supposed to go over a junction at 30mph, but the driver did over this in error, would the track be able to alert the signaller and/or NR of the incident?

Not really no.

Trains do have 'Black boxes' and random downloads are regularly performed and reviewed.

Certain overspeed incidents may also be noticed/reported by signallers; particularly Temporary and Emergency Speed Restrictions (TSRs and ESRs).

 

[Annetts key]

Can the track even know what the speed of the train is, no.
Can the signalling system tell, maybe.

What can tell is a Network Rail employee or a contractor working for Network Rail, equipped with a radar speed gun. I've seen this happen.

Some Hot Axle Box Detectors (HABD) can record the speed of each train that passes over the site.

As said above, systems which take signalling system data can record how long a track circuit or axle counter section is occupied for. As the length of the section is known, the speed of the train can be calculated.

And computer based signalling interlocking records all signalling events including track circuit and axle counter data.

ERTMS will also record data.

Modern computer based axle counter systems may also record axle counter data.

The modern digital TI21/EBI track circuit equipment also records data.

There may also be separate monitoring equipment (provided for maintenance purposes) that records track circuit data.

For the most part, these signalling systems are not routinely used to check for train drivers overspeeding.

Of course, the TOC has access to the on board data recorder. If Network Rail has concerns, they can ask the TOC to provide a copy of this data.

 

[LNW-GW Joint]

In GBR-speak, all the data will be available to everybody (maybe).
No "us" and "them" any more.

 

[dangie]

Simple question, apologies if this has been answered. How accurate is an in-cab speedometer?

 

[TSG]

As pointed out, anywhere that has track circuits/axle counters and data logging (much of the railway) has the raw data from which average speed between two points can be calculated pretty accurately. Frauscher axle counters, which are becoming more common now, can actually give instantaneous speed of passing wheels too

 

[12LDA28C]

Simple question, apologies if this has been answered. How accurate is an in-cab speedometer?

I believe it depends on the stock but certainly on older traction, not particularly accurate and a margin of error of around five per cent is usually taken into account.

 

[abr2024]

Probably should have mentioned this, I’m doing a FdEng in Rail Engineering so looking into this

 

[Supercoss]

Most modern stock can be downloaded , driver management/ competence development managers do this on a regular basis as part of assessment, whilst route knowledge is part of this it is not helped ‘ on the ground’ by missing, dirty, graffiti covered permissible speed indicators trackside.

 

[rower40]

On a long-ago visit to the NRM, I saw an exhibit of a clock that used to be connected to a track circuit on Durham viaduct. If the train took less than 30 (from memory!) seconds to traverse the viaduct, the traction supervisor was to be informed. This was from the 1890s.

So signalling systems CAN (and did) detect overspeeding.

 

[Daniel Pyke]

Can the track report overspeed incidents?

Obviously aware of TPWS but that isn’t what I mean.

Say for example, a train was supposed to go over a junction at 30mph, but the driver did over this in error, would the track be able to alert the signaller and/or NR of the incident?

Not really no. We monitor train speeds as part of our infrastructure monitoring stuff, but it isn't used for surveillance purposes and not currently used in the UK.