Where does the slack come from?

[whole diary]

[willc]

Glance at watch maybe, but nearer the 20 mark than 27. I know the role ATP^▸ (Automatic Train Protection) plays, that's why I said luck. I appreciate that where other trains are plays a part, but if you set off with enough of a gap ahead of you you can take some time back here

[G.Uard]

The average back in those palmy days was around 25-26 minutes, although I do remember runs of around 23 minutes. (I used to commute RDG^‡(resolve)-PAD^» (Paddington (London) - next trains) on a regular basis).  Apparently, drivers were told to 'go like hell' and as (I think I am right in saying), there were no speed limiters fitted, they quite often did.  I have 'timed' speeds of 135 plus between Slough and Maidenhead, but a stop-watch from the carriage window is notoriously inaccurate.  I believe that the distance is 36 miles and 2 chains BTW^▸ (by the way)

[onthecushions]

Some thoughts in the snow:

When HST^▸ (High Speed Train) was introduced (33 years ago!) the official down (Westbound) timings were:

Reading 21.5 minutes, start to pass, 22 minutes stopping. With dwell time about 3 minutes, departure from Reading was 25/26 minutes after leaving Paddington. this was true certainly up to 1988 as I still have the TT. My memories are that this was generally achieved.

The changes since then are:

1. The revised Paddington throat (supposed to accelerate services), which was again revised with lower speeds (40 mph) after the Ladbroke Grove crash. I have the 1991 Railscene cab ride video which shows how much clearer the route seemed before Heathrow Express.

2. The conflict with Heathrow Express, particularly East-bound means frequent signal checks for inbound HST's, adding several minutes, because of poor HST acceleration.

3. Reading's platform 4 used to have a speed limit of 80 mph which has now been reduced to 50 mph. I imagine this means that signalling approach control must now kick in,  i.e. a crawl up to a red signal (RA28), which clears if the train takes long enough but stops the train dead if not. All this adds up to a stranglehold on the main line, slashing capacity, creating queues and blossoming euphemisms from, "waiting for a platform" to the bureaucratically more satisfying, "awaiting platform allocation".

4. Overcrowded HST's take time to empty onto platform 4, lacking 1/3, 2/3 sliding doors and having many un-practised occasional passengers with luggage, who don't shut doors.

5. In compensation, we don't now have 70 mph heritage dmus or 90 mph turbos on the 125 mph main line. The MTU^▸ (Motor Traction Unit) re-engined power cars also seem nippier - does anyone have any figures?

OTC

[eightf48544]

There is also another problem from Padd to West Drayton and that's the speed of response of the IECC^▸ (Integrated Electronic Control Centre). Unlike Slough and Reading MAS which normally works auto i.e a signal will  change up once a train passess the clearing point of the next signal, thus most of the time the signal will be showing green.

Whereas in the IECC area many signals are held at read until the compter ARS^▸ (Automatic Route Setting) decides to change up.

When I travelled regularly on the 17:36 Bourne End first coach left hand side facing, you could see the signals out of Padd. Sometimes you could pick up a double yellow around Ealing pass a single yellow and then get the next signal at green, which means the train in front was at least 3 sections ahead instead of 1 in auto areas, because the IECC was slow in responding. Which means that the run was knocked out of the train but as it was a Turbo not as badly as an HST^▸ (High Speed Train) with ATP^▸ (Automatic Train Protection).

[Boppy]

I've commuted between Reading and Paddington for a good while now and in my experience before the Ladbroke Grove incident the trains were timetabled at 24 -26 mins to do the journey (with the train taking 23mins when there were no hold ups) and often did it in that time.

However, these days I expect more like 30mins for the journey due to the reasons in the last few posts - I still think this is a pretty good time but still on occasions the train manages to do Paddington to Reading in 23mins (I never find this is the case going the other way any longer) and it always makes my proud that the train can be this quick and on time!   Unfortunately, looking up at the screen at Reading when it does it this quickly I then see it has 5 mins or so of slack at Reading to sit there for!

On another note - big thumbs up to FGW^▸ (First Great Western) for a v quick service into Paddington from Reading this morning for me in the snow.  Well done!

[IndustryInsider]

There is also another problem from Padd to West Drayton and that's the speed of response of the IECC^▸ (Integrated Electronic Control Centre). Unlike Slough and Reading MAS which normally works auto i.e a signal will  change up once a train passess the clearing point of the next signal, thus most of the time the signal will be showing green.

Whereas in the IECC area many signals are held at read until the compter ARS^▸ (Automatic Route Setting) decides to change up.

When I travelled regularly on the 17:36 Bourne End first coach left hand side facing, you could see the signals out of Padd. Sometimes you could pick up a double yellow around Ealing pass a single yellow and then get the next signal at green, which means the train in front was at least 3 sections ahead instead of 1 in auto areas, because the IECC was slow in responding. Which means that the run was knocked out of the train but as it was a Turbo not as badly as an HST^▸ (High Speed Train) with ATP^▸ (Automatic Train Protection).

I think that has more to do with the signal spacing and sighting around the Ealing area. If you're following another train close behind the signals are spaced very closely (hence clear quickly) as far as the junction east of Ealing, then get slightly further apart with poor visibility until Southall where the sighting issues are removed by the long straight until nearly as far as Hayes. Net result is that the trains get bunched up a little at Ealing waiting the trains ahead to clear the longer sections, the following train gets a double or single yellow, but by the time the driver has braked appropriately for the poorly sighted signals they have stepped up, and you are then on straight track with the ability to see 2/3 sections ahead on a clear day.

[Btline]

Of course, once Crossrail starts, there will be extra slow, 90 mph max, stoppers to Oxford on the fast lines.

And then consider the Heathrow Hub. All trains will stop there, and will have a large dwell to let passengers with luggage get off.

I predict that scheduled timings will reach 30+ mins after these developments.
 

[IndustryInsider]

Of course, once Crossrail starts, there will be extra slow, 90 mph max, stoppers to Oxford on the fast lines.

I don't think there will be. It simply won't be possible without reducing the HSS^▸ (High Speed Services) service - It's not a case of slowing the fast trains down, there simply isn't the paths for any more trains on the Mains without seriously compromising on the infrastructure. Heathrow Express should, in my opinion, reduce in frequency from every 15 minutes to every 20 minutes as there will be less call for it due to the Crossrail trains heading there from central/east London. That would release one path per hour.

If I can throw my hat in the ring, I fully expect Crossrail to be operating from/to Reading from its inception, and I would bet that the half-hourly Oxford-Paddington stoppers will only run as far as Reading, or possibly divert to Gatwick Airport.

[willc]

I would bet that the half-hourly Oxford-Paddington stoppers will only run as far as Reading

Which was exactly what they were doing today! But with the added benefit that they mostly seemed to be calling all stations, rather than skipping odd stops which they normally do.

[IndustryInsider]

I would bet that the half-hourly Oxford-Paddington stoppers will only run as far as Reading

Which was exactly what they were doing today! But with the added benefit that they mostly seemed to be calling all stations, rather than skipping odd stops which they normally do.

Culham and Appleford always seem to see their most frequent service when an emergency timetable is in place!

[onthecushions]

Looking ahead a little, at the risk of extending the OP^▸ (Original Poster / topic starter),  IC^▸ (Inter City) electrification, Crossrail and Heathrow Hub (they are now calling the perimeter the "campus"!) will require more track for any sort of service quality.

How might this work?

New IC trains will certainly have a 125mph/200kph+ capability and have a good  business case to use their speed. This means that the main lines have to be special - a French LGV^▸ (Large Goods Vehicle) in fact, with closer sleeper spacings, wider separation,  extra signal aspects for each extra 50km/hr above 200 kph, specialised maintenance etc, in short not a mixed traffic and speed railway. This leaves the rest of us in a queue at the speed of the slowest on the relief lines. Now RailTrack did suggest 6 tracks all the way to Reading, a counsel of perfection. Practically, we could have some 6 tracking, or 4-track relief lines  - passing loops in effect, at a number of locations where the formation already exists. We could also use the bays - Platform 5 at Slough etc to terminate stoppers ahead of semi-fasts.

Not perfect but better than sitting at red signals.

OTC

[Btline]

I think 6 tracking is required (with the fast lines capable of 140 mph).

Don't build the Heathrow Hub. The HX and Crossrail will be enough!

Build a spur to have Reading - Heathrow local trains (operated by Crossrail).

[Zoe]

Don't build the Heathrow Hub. The HX and Crossrail will be enough!

I'm not sure that many people will use Crossrail to Heathrow rather than the Piccadilly line as there are still going to be premium fares on the Hayes to Heathrow section.

[Btline]

Don't build the Heathrow Hub. The HX and Crossrail will be enough!

I'm not sure that many people will use Crossrail to Heathrow rather than the Piccadilly line as there are still going to be premium fares on the Hayes to Heathrow section.

I forgot about the Tube - Another reason why not to build the Hub!

And if a Waterloo - Terminal 5 - Heathrow Central service gets build, that'll be another reason.

Chiltern were considering a direct line from their route, through Uxbridge to the airport, as well. I doubt this gets built.

[IndustryInsider]

I think 6 tracking is required (with the fast lines capable of 140 mph).

It would be nice. But it ain't gonna happen! You could (and probably will with Crossrail) have 5 tracks between Airport Junction and Iver/Langley. You can even throw in a few passing loops here and there, but to have 6 tracks between Paddington and Reading think of the civil engineering that would be required...

1) Rebuild of ALL stations

2) Widening of 'tunnels' at Ealing

3) Replacement of Wharnecliffe Viaduct and Hanwell Viaduct

4) Replacement of Maidenhead Thames bridge

5) Replacement of countless other bridges

6) Long embankments/cuttings between Taplow and Twyford to be widened

Imagine the cost of that little lot. And I could go on....


More likely/sensible is a dedicated High Speed line following alongside the M4 corridor.