Slack

[whole diary]

[Super Guard]

Secondly - "Slack times lead to slack operations (dispatch, etc.)"? A rather sweeping statement - but I only work on the railways, so I bow to your greater knowledge. You can back this statement up with examples, I presume? 

I make sure my trains are rolling at :00seconds whether they are here for 1 minute or 10... 

[willc]

Take a look at the Cotswold line. Slack increases almost every timetable change, no improvement in punctuality.

Not true. The East customer panel minutes give the following performance stats mid-January:

^   P10 best recorded:      93.87%

^   December 2008 timetable uplift (P11 to date)
^   Outer Thames Valley:      91.67%   
^   Inner Thames Valley:      97.00%
^   Cotswolds:         93.81%

The latter figure was about 64 per cent in January last year and I would have to say my own experiences recently would tend to bear out a 90 per cent-plus figure, which reflects credit on FGW^▸ (First Great Western) and Network Rail staff, never mind the slack - performance generally on the route is far, far better.

The only up side of the 8.52 from Malvern being Turbo-ised is that its punctuality is first class now, indeed it is usually early into Oxford (32 or 33 minutes running time from Moreton being typical) and coupled on to the second set - when it's there - before the booked arrival of 10.27, thanks to the superior acceleration from station stops. And that 97 per cent for inner-suburban is up with Chiltern's figures.

[IndustryInsider]

The only up side of the 8.52 from Malvern being Turbo-ised is that its punctuality is first class now

The punctuality of the train has also been given a boost due to the tight turnaround at Great Malvern. It nearly always left Malvern late as a HST^▸ (High Speed Train), running the risk of losing its path.

In the 15 minutes from arrival at 08:37 at Great Malvern to departure at 08:52 the train has to shunt the mile to Malvern Wells and the driver has to change ends and drive back to Gt. Malvern. That is virtually impossible in a HST in 15 minutes due to the length of the train and all the tests that have to be carried out in the cab before departure. In a Turbo it's pretty much 'master key out, walk 70 metres, master key in and off you go'. That may well have been a factor in the decision to choose that train to be replaced by a Turbo?

My post-redoubling Cotswold Line Timetable suggestion of a couple of weeks ago took that sort of thing into account, with the minimum turnaround of a HST at Great Malvern being 23 minutes.

[paul7575]

What is the difference between slack and prudent timetabling? Since the December change, the Cardiff - Portsmouth trains sit in Southampton for about 5 mins in each direction, and now seem to nearly always leave as timetabled. Presumably that has benefits to all operations at Southampton, and SWT^▸ (South West Trains), XC^▸ (Cross Country Trains (franchise)) and Southern see service reliability increase as well...

Paul

[eightf48544]

What is the difference between slack and prudent timetabling? Since the December change, the Cardiff - Portsmouth trains sit in Southampton for about 5 mins in each direction, and now seem to nearly always leave as timetabled. Presumably that has benefits to all operations at Southampton, and SWT^▸ (South West Trains), XC^▸ (Cross Country Trains (franchise)) and Southern see service reliability increase as well...

Paul

A very interesting question.

Whilst waitng 5 minutes at Southampton may get FGW^▸ (First Great Western) trains leaving on time but may also deny SWT or XC of a path through the station because you could have 2 trains standing for 2 minutes each using that platform within the 5 minutes. Assumming the signals allow a train to occuppy the platform a minute after the previous departure.

It's one of the problems at Reading that the platform entrance signals are so far away that it takes a stopped train a couple of minutes to pull into the sation after the departure of the previous train.

The Up Relief from Tilehurst  is particualrly bad where if the junction is in use you are held right out at Cow Lane where it can be 3 or 4 minutes before the train gets into the platform.

in answer to Paul's question I believe the key word for train running in general should be brisk. So it's quick despatch, good acceleration, max speed,  hard braking, short station stops. Just like we used to run the Southern Sububan services during my time on the region.

Gerry Fiennes in his book I Tried to Run a Railway has an interesting description of turning a train around on the Shenfield electrics at Liverpool Street in 5 minutes.

He also has an interesting comment of GW^▸ (Great Western) working when Gerneral Manger WR about Reading. He was on platform 5 with a London Express which was being held for a late running Newbury connection. The passengers were strolling over so he said to the Inspector "Blow your whistle to move them along." To which the Inspector replied "We don't blow whistles at passengers from Newbury sir."

[Btline]

Having waiting time at the station reduces capacity at the station and lengthens journey times for longer distant passengers.

I believe the key word for train running in general should be brisk. So it's quick despatch, good acceleration, max speed,  hard braking, short station stops.

I agree with this statement. Slack does not help in this respect.

And, in my experience, having a train waiting for 5 minutes at a station does not guarantee departure on time!

[devon_metro]

It also allows for recovery. If every station prior to Southampton was busy, with a few less able passengers boarding, that 5 minutes would soon get eaten into.

Fact is, its not going to change, unless Network Rail charge less for delay minutes!

[Oxman]

Another interesting example:

Up local stoppers from Oxford in the previous timetable where scheduled to leave at xx.21, six minutes after the AXC^» (Arriva Cross Country - about) xx.15 service to Bournemouth. This was quite often late by a few minutes - the AXC service was allowed up to 8 mins lateness and it would still precede the stopper.

The stopper provided a six minute connection at Didcot for Bristol and the West. Whenever the AXC train was a few minutes late, the connection at Didcot was missed. Particularly a problem in the  evening peak, when 60+ passengers would change at Didcot for Swindon, Bath etc.

In the current timetable, the stoppers leave at xx.07, with the AXC service following at xx.16. Its now very rare for connections at Didcot to be missed. The stopper sits at Didcot for 10 mins to allow the AXC service to pass, then resumes its journey, more or less in the old path.

There is a similar arrangement in the down direction.

The result is that passengers changing at Didcot are very happy. The connections work very well, you just have to be at Oxford a bit earlier. The downside is that connections out of the AXC service are worse - you have to wait 22 mins at Oxford for a connection to Didcot, rather than than 6 minutes as in the previous timetable.

For passengers travelling on the stopper from Oxford beyond Didcot, there appears to be 10 mins of slack at Didcot - the same applies in the down direction.

So, one group of passengers are see an improved service, and another (smaller) group see a worsening. However, punctuality has improved enormously, so both groups see some improvement, albeit at the expense of increased journey times.

The message seems to be that introducing slack can benefit passengers. Reliability is often more highly valued than speed.

[eightf48544]

For passengers travelling on the stopper from Oxford beyond Didcot, there appears to be 10 mins of slack at Didcot - the same applies in the down direction.

So, one group of passengers are see an improved service, and another (smaller) group see a worsening. However, punctuality has improved enormously, so both groups see some improvement, albeit at the expense of increased journey times.

The message seems to be that introducing slack can benefit passengers. Reliability is often more highly valued than speed.

A very interesting analysis, but I would suggest that the problem of the Oxford following or proceeding  the XC^▸ (Cross Country Trains (franchise)) is more of a timetabling/timekeeping problem more than artificially introduced slack although the 10 minute wait at Didcot could be considered too long.

Conventional wisdom would be that a stopper follows a fast especially from somewhere like Oxford where the stopper is a startup. By putting the stopper in front of the XC suggests that there is an addmission that there is not much faith in the XC arriving at Oxford ontime, to allow the stopper to follow and still make the Westbound connection at Didcot.

At somewhere like Oxford where the XC and stopper use the same platform it ought to be possible to time the stopper to leave 5 minutes after the fast. Similarly in the Up direction it ought to be possible to time the stopper to arrive 5 minutes in front of the fast.

It requires discipline to run the railways as I say briskly. Plus blowing whistles loudly at passengers!

[IndustryInsider]

Having a 10 minute stop over at Didcot on every train is far from ideal. There are quite a few through journeys from Oxford to Cholsey and Goring that now take much longer than they have previously, and as 'Oxman' points out connections from XC^▸ (Cross Country Trains (franchise)) trains from the north for Didcot are now poor - but then again they are more robust as how often was the XC late enough to mean the stopper left first? The westbound connections at Didcot are quite important for journeys from Oxford and it is good that they are now more robust.

I guess that it's a case of swings and roundabouts - with such a traffic intensive route, you are never going to tick all the aspirational boxes that would provide a great service for all.

[tramway]

Vitually all the peak time morning services from West Wilts to the North of Bristol are diabolical.

The classic is if you don^t make the 0724 Trowbridge Parkway then there is little point catching the 0744 to Great Malvern which normally arrives in BTM^▸ (Bristol Temple Meads (strictly, it should be BRI)) ahead of the 0829 timetable and doesn^t depart until 0841. You can be sat there for 15 min. Arrival Filton 0848. I will have left home at approx 0735 to do this journey.

We then come to the next service at 0800 to Cardiff, due in BTM 0840 (read 0837) depart 0854, where the hell does that come from, everyone now has to swap platforms to get the 67^s from Taunton, arrival 0857.

I can therefore leave home almost 15 min later to do the journey in almost the same amount of time AND change trains en-route.

Compare that with the Filton Trowbridge evening service on the Cardiff Pompey, d xx09 a xx53, approx 40 min, the best part of 20 min difference in the peak, and this on a 35 mile journey.

If the DafT have any prospect for West Wilts to be part of the Greater Bristol metro system then I pray that this is sorted.

[Tim]

Mornings on the Pompy-Cardiff route as a whole are very poorly timed.  Its not just your journey, Bath-Cardiff (which I do occasionally) is very poor.  There ought to be a train that leaves at about 8am and arrives at about 9am, but there isn't.  I can get to central London from Bath by 9:30 by leaving on the 7:42 9arriving Padd 9:15 and then a Dash to the Tube - mind you it used to arrive Padd at 9:05!).  To arrive in Cardiff by the same time I leave Bath at 7:34 which is rediculous considering Cardiff is much closer and their is an approximately 1/2 hourly service to Both Cardiff and London from Bath.

[thetrout]

It's not just about waving a train goodbye, you are correct about that - there are a LOT of other issues involved in dispatch that I presume you mean when you say "etc". - however, the crew should be already on the train, otherwise, who has just brought it into the station... 

The main thing about dispatch IMO^▸ (in my opinion) is making sure the driver is in the cab and not chatting on their mobile on the platform

[Btline]

I am only commenting on what I experience. And when I talk about despatch - it's not just about waving a train off, it's the arrival of train crew as well, etc.

It's not just about waving a train goodbye, you are correct about that - there are a LOT of other issues involved in dispatch that I presume you mean when you say "etc". - however, the crew should be already on the train, otherwise, who has just brought it into the station... 

Well, presumably the crew that brought the train in are in the staff room on a break before their next working.

[The Grecian]

On the subject of slack, I used the Brizzle-Paddington line last weekend and the train arrived at Paddington over 5 minutes early, in just 24 minutes from Reading. On the return the train was 10 minutes late leaving Reading due to engine problems and we were informed the train would not exceed 100mph as a result. Even then, it was only 6 minutes late into Bristol. I suspect this might be a result of the fines incurred for late running.