Through passenger train speeds at Swindon and Reading

[coppercapped]

I seem to remember that when 125mph HSTs were introduced in 1976 there was amused comment about there being a "speed restriction" to 100mph through Reading.

If I remember rightly the speed limits in the days of steam and diesels on the Mains at Reading were 75mph on the Down (past the old Platform 4) and 80 mph on the Up. The turnouts for the Up Main Platform Loop were both 25mph.
These limits remained into the HST era when a combination of more trains stopping, the wide and heavy Mark 3 coach doors having to be pushed open against the tilt of the coach and the big step down to the platform resulted in the cant on the Down Main being reduced and a 50mph limit imposed.

So, after 40 years we're back to where we were before! In fact slightly better!

 

[MarkyT]

BR added an extra signal on the down main approach to old platform #4 sometime in the 80s or 90s. It avoided the next train waiting for clearance nearly a mile away, London side of Reading East Jn by the gasometers. The low approach speed meant a simple standard 4-aspect sequence could be used with a short overlap at the additional signal. There was already a signal much closer in on the down relief.

 

[Dren Ahmeti]

If I remember rightly the speed limits in the days of steam and diesels on the Mains at Reading were 75mph on the Down (past the old Platform 4) and 80 mph on the Up. The turnouts for the Up Main Platform Loop were both 25mph.
These limits remained into the HST era when a combination of more trains stopping, the wide and heavy Mark 3 coach doors having to be pushed open against the tilt of the coach and the big step down to the platform resulted in the cant on the Down Main being reduced and a 50mph limit imposed.

So, after 40 years we're back to where we were before! In fact slightly better!

I believe the current cant on the DM/UM allows for the full 125mph through the platforms since the remodelling, but it’s signal spacing through and out past the station to the West that’s the issue.
Issue is, if the line speed through Reading is raised, then Didcot East Junction, Swindon (85mph) and Wootton Bassett Junction (70mph for diverging trains) would just become more of a pinch-point timetabling-wise.

The new TT has trains going non-stop through many of the loops, not just DM/UM, under/overtaking trains recessed in the platforms - ARS is going to have its work cut out!

 

[HowardGWR]

Platforms #9 (DM) and #10 (UM) at Reading allow speeds of 80/HST95 and 85/HST95 respectively today, although the new remodelled track geometry is apparently suitable for even higher speeds in the future if desired. Signalling is the limitation today, particularly signal spacing to allow 'closing up' of the majority stopping service on the Main (fast) lines, but future cab signalling should be able to allow an increase in through speed while maintaining the close-following capability for stopping trains.

What are the peculiarities at Swindon, do you know Mark? I know the reduction from four lines between the main platforms to three is a pain from that standpoint. I believe it had to do with the building of the tower block?

 

[Brissle Girl]

What are the peculiarities at Swindon, do you know Mark? I know the reduction from four lines between the main platforms to three is a pain from that standpoint. I believe it had to do with the building of the tower block?

Signal Point you mean? The one that's been completely vacant for about 10 years now, with plans to convert it to flats apparently coming to naught.
As to Swindon, when the up goods loop ( I think as was) from Rushey Platt was put into regular passenger use just over 10 years ago, the non-diverging line at RP was reduced to 85mph with the diverging route being 75mph. I recall this was so to avoid too much of a difference between the straight and diverging route, which would have necessitated approach control, and a greater restriction. The benefit was a faster run into the platforms at Swindon than is the case if you carry on down the main until within sight of the platform. But ironically, it meant non-stopping trains have a greater restriction than before. Not a problem when it was done of course.

 

[MarkyT]

What are the peculiarities at Swindon, do you know Mark? I know the reduction from four lines between the main platforms to three is a pain from that standpoint. I believe it had to do with the building of the tower block?

At Swindon station there was a complete additional island platform on the down side that I think was removed entirely at resignalling in 1968, paving the way for construction of the tower block, and today there is a narrow access road around Signal Point between the building and platform #4. This is used as an emergency route, so couldn't have been closed off to create space for a new platform facing onto the old down goods loop. Hence that line had to be removed to create the space for the platform. An alternative to create a full length platform further east on the DGL (a rebuild/extension of the former parcels platform) would have encroached on the throat junction at the east end of the station, and would have required significant expensive track layout remodelling.

Signal Point you mean? The one that's been completely vacant for about 10 years now, with plans to convert it to flats apparently coming to naught.
As to Swindon, when the up goods loop ( I think as was) from Rushey Platt was put into regular passenger use just over 10 years ago, the non-diverging line at RP was reduced to 85mph with the diverging route being 75mph. I recall this was so to avoid too much of a difference between the straight and diverging route, which would have necessitated approach control, and a greater restriction. The benefit was a faster run into the platforms at Swindon than is the case if you carry on down the main until within sight of the platform. But ironically, it meant non-stopping trains have a greater restriction than before. Not a problem when it was done of course.

Correct. 10mph difference or less means no approach release neccessary. That's just one way of doing it though, that was probably very easy to do with the old signalling with minimal rewiring, but Flashing aspects or splitting distants might be employed instead. Going by the Sectional Appendix, it looks like the current signalling retains this 'feature'. I worked in Signal Point for a couple of years back in the mid 1990s. My ground floor office window overlooked the down goods loop, before the new platform construction.

 

[jfisher21]

Watford Junction waiting for the pendolino to Birmingham on platform 6 can be a bit scary, have seen a few people and cases too close to the edge when the preceding non stop Manchester train goes through at 125!

 

[Fawkes Cat]

I'm aware that the station building there is a historic listed structure (probably the only one that Slough town runs to),

Don't be snotty. https://britishlistedbuildings.co.uk/england/slough#.XeisWM2nyDY

but whoever did the risk assessment of this arrangement needs to have another serious think

As a layperson, agreed.