APT CAPT line speed indicator

[Telcontar]

I just watched this:

http://www.youtube.com/watch?v=oSMSSdL2yeo

I always wondered what that little square window on the APT driver's desk did -- apparently it's "CAPT", some sort of in-cab line speed indicator. (First mentioned at 3:12)

Anyone know anything about this? And what happened to it? It's not clear from the video whether it had any intelligence and thereby any override ability, and whether the trackside equipment was sending out a static or dynamic speed.

 

[Manchester77]

CAPT stands for Control Advanced Passenger Train. My understanding was that it stopped the train from overspeeding / over tilting but I can't remember exactly

 

[Broken Viking]

From what I can recall, C-APT (Control - Advanced Passenger Train) was used for speed management and limit setting. This was done by means of passive transponders in the four-foot bolted to the sleepers, which were energised by an induction coil and which transmitted static data to a receiver mounted under the APTs leading cab - An early implementation of RFID.

AFAIK this data consisted of speed limits for the current and following signal sections, but probably not tilt data; The APTs tilting system was entirely reactive. It was used in addition to conventional lineside signs (C-APT presumably intended to be a more basic answer to TVM) with C-APT setting a maximum speed limit, above which the train would either inhibit further acceleration, or e-brake AWS style.

I've been told that the Pendolinos use a modernised version of C-APT to receive speed and tilt profile data, but I havn't been able to verify this.

Hope this is useful!

 

[Telcontar]

Thanks!

 

[Railsigns]

The C-APT display also showed a letter "J" to the left of the speed value on the approach to a diverging junction.

A change of display to a lower speed had to be acknowledged by the driver, similar to AWS.

Many of the C-APT transponders are still in situ to this day.

 

[edwin_m]

The TASS sysstem used on Pendolinos does the same sort of thing as C-APT but uses different hardware.

 

[cjmillsnun]

From what I can recall, C-APT (Control - Advanced Passenger Train) was used for speed management and limit setting. This was done by means of passive transponders in the four-foot bolted to the sleepers, which were energised by an induction coil and which transmitted static data to a receiver mounted under the APTs leading cab - An early implementation of RFID.

AFAIK this data consisted of speed limits for the current and following signal sections, but probably not tilt data; The APTs tilting system was entirely reactive. It was used in addition to conventional lineside signs (C-APT presumably intended to be a more basic answer to TVM) with C-APT setting a maximum speed limit, above which the train would either inhibit further acceleration, or e-brake AWS style.

I've been told that the Pendolinos use a modernised version of C-APT to receive speed and tilt profile data, but I havn't been able to verify this.

Hope this is useful!

CAPT wouldn't stop the driver exceeding the speed limit as it was more a warning and advisory system in the same way that AWS is.

It was done to let the driver know what the speed limit was, and any divergent routes set and their limit, but it was for the driver to use that data and control the train.

EDIT: linky.. http://www.apt-p.com/aptcapt.htm

 

[asylumxl]

According to the link posted above:

A secondary use of C-APT is to close air intakes when approaching tunnels to prevent ear discomfort to passengers.

Which is something I was actually thinking about the other day!

 

[Telcontar]

EDIT: linky.. http://www.apt-p.com/aptcapt.htm

Ah, if I spell it '"C-APT" advanced passenger train' instead of '"CAPT" advanced passenger train' in Google search, it actually finds that page. Lots of things are easy to find when you know the correct spelling or the correct terminology!

Which is something I was actually thinking about the other day!

I was thinking only the other day about this, but I thought the problem was caused mostly by opened windows. I don't remember whether fully air-conditioned trains—with fixed windows—are immune to ear bashing. I suppose now they can just use GPS to take care of this.

 

[asylumxl]

I was thinking only the other day about this, but I thought the problem was caused mostly by opened windows. I don't remember whether fully air-conditioned trains—with fixed windows—are immune to ear bashing. I suppose now they can just use GPS to take care of this.

Electrostars are most definitely susceptible to the pressure differential as the intakes do not close and the doors are not airtight. The Javelins on the other hand do have pressure sealed carriages, which makes sense at 140mph diving in and out of tunnels.

 

[Telcontar]

Does anyone know whether APT-E had C-APT, or only APT-P? i.e. which page on Wikipedia I should add this to.

 

[Manchester77]

Looking at the cab it doesn't look like it did, and also I don't think they'd have gone to the trouble of installing it on the MML & GWML just for one train to test (it was intended for full service on WCML)

 

[Telcontar]

Duh, why didn't I think of that. Thanks.