Where does the slack come from?

[whole diary]

[Btline]

Many FGW^▸ (First Great Western) journeys have increased in length over the years.

On routes such as the Cotswold, it is because of single track.

But why have journeys to Bristol and Plymouth increased? Where is the slack put (apart from before the final stop)?

When Reading is finished, will that alter slack?

[devon_metro]

There's little slack as far as Reading. There is slack between Reading and Swindon, chippenham and bath and bath and Bristol. There is slack between tiverton and exeter on sw services.

[Zoe]

There is slack between tiverton and exeter on sw services.

Some services also appear to have a bit of slack between Reading and Taunton, I have been on a train before now that has done London to Taunton in 1 hour 40 minutes and then had to wait a for a bit at Taunton.

[inspector_blakey]

DID^» (Didcot Parkway - next trains)-SWI^» (Swindon - next trains) usually timed at 19 - 20 minutes. A healthy HST^▸ (High Speed Train) can (and often does) make it in about 15.

[Btline]

So why is the slack there?

Is it really needed?

[Zoe]

So why is the slack there?

Is it really needed?

So the trains can be delayed by a bit and still arrive on time?

[devon_metro]

So why is the slack there?

Is it really needed?

Less money in delay minutes. Don't expect any changes with franchise finances tight. When the hsts get a mini buffet and the buffet car us lost on Bristol runs it may mean a few minutes are shave off the times.

[bemmy]

It's about newspaper headlines -- the government's obsession with statistics is to do with appeasing the press, not the needs of passengers. It's exactly the same principle as the school league tables, which do nothing to drive up standards for the majority of pupils.

So, it's better to have a train timetabled to take 1:45 from London to Bristol that arrives on time less than 10 minutes late 90% of the time, than one timetabled to take 1:35 that arrives less than 10 minutes late 80% of the time.

In practice, most trains from London that I've been on get delayed before or at Reading, and make up the time by Swindon or Chippenham. So in theory, after the Reading flyover is built, it should be possible to remove some of the slack. However, if the statistical priorities remain the same, they will use this as an opportunity to improve punctuality.

And the system works! We've all seen the headlines about "Record levels of punctuality!", and people who don't use trains don't need to realise that the trains are getting slower every year, and besides, "since records began" means "since 1995 when the railways were half-destroyed". 

[Electric train]

There's little slack as far as Reading.

What!!!! there's loads of slack in the Reading / Paddington locals, in fact its farcical, with trains often sitting in platforms for several minuets because there have arrived so early.

[devon_metro]

There's little slack as far as Reading.

What!!!! there's loads of slack in the Reading / Paddington locals, in fact its farcical, with trains often sitting in platforms for several minuets because there have arrived so early.

I was talking about HSTs^▸ (High Speed Train)

[willc]

But in 1976 BR^▸ (British Rail(ways)) managed 20 minutes start to stop Paddington-Reading with HSTs^▸ (High Speed Train), where 25-27 minutes is typical now. I have been on several late-running services from Oxford in recent years which have had their Slough stop dropped to recover some time and made the trip in 20 minutes, though I guess luck played a part too, considering the number of trains out there these days.

[devon_metro]

Following the rail disasters near Paddington speed limits near to the throat are much lower, HSTs^▸ (High Speed Train) are 2+8 instead of 2+7, TPWS^▸ (Train Protection and Warning System)/ATP^▸ (Automatic Train Protection) prevents speeding which was common. etc

[willc]

But with good train handling it can be done, just as on the Cotswold Line drivers can make a mockery of the slack timings if they have been delayed earlier their journey - without breaking any speed limits.

[Btline]

So will it take an additional track or two btw Reading and Paddington to remove the slack?

Do trains ever reach 125 mph these days (on that stretch)?

[IndustryInsider]

But in 1976 BR^▸ (British Rail(ways)) managed 20 minutes start to stop Paddington-Reading with HSTs^▸ (High Speed Train), where 25-27 minutes is typical now. I have been on several late-running services from Oxford in recent years which have had their Slough stop dropped to recover some time and made the trip in 20 minutes, though I guess luck played a part too, considering the number of trains out there these days.

Will - are these actual stopwatch recorded running times, or 'glance at the watch as you come into the platform' estimates? I would like to see start/stop timings of 20 minutes with the current infrastructure, safety systems and driving standards. 22 minutes is pretty much the minimum I have ever seen with a clear run and an aggressive driving technique.

Even the Railway Performance Society whose members have been recording regularly for over 30 years have only ever recorded best times of 21m 41s (Up) and 20m 46s (Down). http://www.railperf.org.uk/fast/Great_Western-CrossCountry.pdf

ATP^▸ (Automatic Train Protection) makes such a difference, whereas before a train could hit Reading platform at over 45mph with the brakes in hard and stop, now ATP will apply the emergency brakes if you try anywhere near that speed. That means the train will grind to a halt halfway down the platform, so it is not surprising drivers are much more cautious. The 'freedom' of no ATP, such as on the Cotswold Line, means drivers can push the boundaries a bit further if needed.


And, to Btline, during normal running all non-stop HST's from Paddington-Reading will reach 125mph between Airport Junction and West Drayton and then not have to brake for Reading until Sonning Cutting.