Great Western Coffee Shop

That's the same train, right?

I think have been told there's an absolute minimum of 10 minutes to turn round a train at Westbury if it's going via Trrowbridge, as "they" have to be very sure that it'll be on time when it gets to the Bristol Area.

Have I been told right?  How come a train can be scheduled with a one minute tirn around at Severn Beach - and in the peak too - if it has to be on time for sure whnen it gets to the Stapleton Road to Temple Meads stretch?

There was an article in this month's Modern Railways about how trains terminating at Wrexham Central are scheduled to arrive two minutes after they depart!  It's one of the fiddles to reduce the risk that trains will arrive late and thus trigger performance penalties.

You will notice that the trains are scheduled 9 minutes from St Andrews Road to Severn Beach but only 6 back...

Same goes for the Avonmouth terminaters. 5 mins between Shirehampton and Avonmouth but only 3 mins for the return working.

On Sunday, I was on the 17:23 to Avonmouth which was operated by the ATW 150.  The train arrived at about 17:21 (due 17:19), passengers were unloaded and next lot loaded very quickly.  Within 3 minutes of arriving, the train had left.  That included the time for the driver/guard to swap ends.

The arrival time in the working timetable will no doubt be a few minutes before 17:53.

The minimum turnaround time for each station where trains usually terminate is specified in the Rules of the Plan. On branch lines it's often the minimum 3 minutes, but with an additional rule of no more than 3 consecutive minimum turnarounds - which is why, for example, a half-hourly service on the Henley branch is possible, but the daytime service is every 40 minutes.

This is very interesting (and pertinant to what I'm asking) but I'm not sure how to interpret it - it raises more questions than it answers, but perhaps of necessity.

* Trains usually take 7, 8 or 9 minutes from Trowbridge to Westbury - with occasional ones taking 6 or 10.  From Westbury to Trowbridge, the time is almost universally 5 minutes, with the very occasional 6 minutes.  May I take it that the "working timetable" for a train that has 8 minutes to get from Trowbridge to Westbury really has it arriving there three minutes early?

* The "Rules of the plan" say 10 minutes at Westbury - I think that was what was being referred to.  Is that based on the working timetable (so that a public timetable could show a 7 minute turn around for a train that is scheduled to take 8 minutes from Trowbridge) or the public timetable (in which case, the real scheduled turn around time wouldbe a minimum of 15 minutes for that train with the 10 minute schedule)?

* What are the rules after three minimum turn arounds?  An extra minute?  An extra five?

* Why is the Westbury "base" figure so much higher that for other places?  150s don't "stretch" to 3 times there normal length when they enter Wiltshire ;) so it's no longer walk for the crew, and overcrowding / delays tend to be more of an issue at Trowbridge and Bradford-on-Avon, and on trains that are NOT ending at / starting at Westbury.

I might appear to be a little pushy on the questioning here - I'm trying to make sure I understand issues as to what is and isn't possible.

Not sure if this helps, Graham, but I've just checked five random trains from Trowbridge and Westbury and the 'working' times and the 'public' times were the same (either 7 or 8 minutes) except for one train where they differed by 1 minute.

The discrepancy in direction time may be due to a pathing allowance, speed the trains can enter the station (approach control signals, etc.) or other reasons - I guess if anyone regularly uses the route they could see how long it actually takes one direction compared with the other?  I don't get down that way very often at all.

Disclaimer: this is based on observation/research/guesswork!

Going towards Westbury: the ROTP will also has a section stating minimum timing allowances approaching key points. So approaching Westbury there is a 1 minute minimum applying to the working timetable. The public timings may add further padding, particularly when trains terminate. THe matter is confused further by pathing time - towards Westbury this might relate to platform/junction conflicts; going the other way it might relate to headways.

From Westburty: the 5/6 minute variation might come down to half minutes. Often in cases like thatn it turns out that the advertised dwell time also varies by a minute, and the variations average out over the journey, if that makes sense. From observation it seems that half minute arrivals tend to be rounded up in the public timetable.

For example:
Dep Westbury 10.00, arr Trowbridge 10.05, dep Trowbridge 10.06 might be published with those exact times.
But dep Westbury 10.00+1/2, arr Trowbridge 10.05+1/2, dep 10.06+1/2... might be advertised as dep Westbury 10.00, and arrive/depart Trowbridge both at 10.06.
In both cases I've assumed 5 minute running time, but the public times vary between 5 and 6.


I'm fairly certain it would be based on the working times. Otherwise many of the 'west' services have 'illegal' turnarounds! Similarly with ordinary dwell times - HSTs don't really have 0 minute stops at Swindon etc.


That is the question that springs to mind! I suspect when the rules are vague or flexible it comes down to the discretion of some timetable person at Network Rail to agree or disagree to the times put forward by the TOC.


As suggested, perhaps it's related to making things run on time through the Bristol pinch point... but then the same issues apply in many places. 3 is the minimum, but having a quick scan through, 10 is also common - e.g. it's the minimum turnaround for a DMU at terminating at Swindon. At many locations there are many minimum values depending on journey origin/length - see Bristol and Paddington.
I wonder if it's based partly on statistics - if a location happens to have frequent late starts on certain flows, or issues with knock-on delays, perhaps someone nudges up the minimum turnarounds.
Incidentally, the Westbury value is 10 minutes 'from Weymouth/Bristol/Salisbury' - so a Melksham line service could turn around in 3 ;-)

Regarding the 10 minutes at Westbury, this may be to allow for the fact that many "west" trains change crew there, which (at least based on my not particularly scientific observations) takes a little longer than sinply changing ends whilst the relief crew is appraised of anything they need to know by the previous staff.

Many thanks for the various feedbacks on his ... I certainly feel somewhat more informed now, even though (ironically!) a "TransWilts" service should be "Trans"ing through Westbury and not terminating there.

How much station dwell would be needed for an "II Electric Horseshoe" service at Westbury  ;) ?

Only 3 minutes for a DMU according to the 2011 Rules of the Plan.