Use of allowances in the working timetable - when did it start?

[TheDon88]

An interesting question came up at work today, which I don't know the answer to. So I've opened it up to the esteemed folk on these forums

In the Working Timetable, allowances are added to schedules reflecting different elements of operations:

• [Engineering] allowances ("Box time") - To cover the impact of planned temporary speed restrictions associated with engineering works on the network.
• <Performance> allowances ("Diamond time") - To cover anticipated time loss across sections of a journey.
• {Adjustment} allowances ("Squiggly time") - To cover situations where a train will be performing a move that means it will be unable to meet its Sectional Running Time for that section. Usually, this is because the train is not travelling on the fastest route between the two consecutive timing points, for which that particular Sectional Running Time is calculated. This could be due to needing to brake for a slow-speed junction, approach controls, or acceleration to prevailing line speed after passing through a slow-speed junction.
• (Pathing) allowances ("Circle time") - To compensate for an increase in running time in a section due to the service sighting a signal aspect that would prevent it from meeting its SRT and to meet applicable Timetable Planning Rules, such as maintaining headway or a junction margin.

The first three are mandated in the Timetable Planning Rules and the last one is applied "at the discretion of the planner".

The question is, when did these allowances first come into use in developing the working timetable?

Given splitting distants existed a long while ago (Great Western Railway before First World War), I'd argue that the adjustment allowances must come from before then, but I can't really be sure.

 

[The Planner]

An interesting question came up at work today, which I don't know the answer to. So I've opened it up to the esteemed folk on these forums

In the Working Timetable, allowances are added to schedules reflecting different elements of operations:

• [Engineering] allowances ("Box time") - To cover the impact of planned temporary speed restrictions associated with engineering works on the network.
• <Performance> allowances ("Diamond time") - To cover anticipated time loss across sections of a journey.
• {Adjustment} allowances ("Squiggly time") - To cover situations where a train will be performing a move that means it will be unable to meet its Sectional Running Time for that section. Usually, this is because the train is not travelling on the fastest route between the two consecutive timing points, for which that particular Sectional Running Time is calculated. This could be due to needing to brake for a slow-speed junction, approach controls, or acceleration to prevailing line speed after passing through a slow-speed junction.
• (Pathing) allowances ("Circle time") - To compensate for an increase in running time in a section due to the service sighting a signal aspect that would prevent it from meeting its SRT and to meet applicable Timetable Planning Rules, such as maintaining headway or a junction margin.

The first three are mandated in the Timetable Planning Rules and the last one is applied "at the discretion of the planner".

The question is, when did these allowances first come into use in developing the working timetable?

Given splitting distants existed a long while ago (Great Western Railway before First World War), I'd argue that the adjustment allowances must come from before then, but I can't really be sure.

Pathing shouldn't be at the discretion of the planner, performance time would be and is normally a TOC request.

 

[jfollows]

In the earlier days, when I started looking at working timetables, there were fewer categories than there are today.
For example, 1973-74 Section M LM region, but probably similar elsewhere there were
[] but in a proper box "Indicates the number of minutes allowed for temporary speed restrictions and other engineering work."
() but in a proper circle "Extra time for pathing requirements"
and the latter was - as today - to allow for conflicts at junctions or catching up with slower trains in front.
1950s didn't appear to have either, but I don't have many examples.
But my answer would be that your <Performance> and your {Adjustment} times are newer inventions/innovations.
However I am only a consumer of the end result - the working timetable - I have no insight into how it was put together.

 

[TheDon88]

Pathing shouldn't be at the discretion of the planner, performance time would be and is normally a TOC request.

When I say "discretion of the planner", my point is that they aren't mandated in the Timetable Planning Rules (TPRs), though there may be rules preventing their application in certain situations. The quote marks are doing a lot of heavy lifting!

The inclusion of performance time is still embedded in the TPRs, likely added as a result of a TOC request, as you mention.

 

[jfollows]

Further to my observations above, my 1990-91 timetables are similar (to my 1970s timetables in respect of allowances) whereas my 1991-92 timetables refer additionally to a
<> performance allowance (but in a proper diamond)
which was new. The timetable compilation rules may have included such an allowance previously, but it wasn't shown in the WTT before then I don't think.

 

[louis97]

When I say "discretion of the planner", my point is that they aren't mandated in the Timetable Planning Rules (TPRs), though there may be rules preventing their application in certain situations. The quote marks are doing a lot of heavy lifting!

I understand your point, however the presence of a rule in the TPRs is basically mandating pathing time be added where a rule cannot be met by other means (extra dwell time for example). Also some rules are of a less value with some pathing time present on approach to the location to which that rule applies. Of course, that doesn't stop the many situations where the rules are not followed, but the same could be said for all of the allowances!

 

[Wilts Wanderer]

The concept of ‘recovery time’ was I believe a BR invention in the 1950s; but it was applied in a very ham-fisted manner, for instance all Up expresses bound for Kings Cross having 18 minutes of recovery time between Peterborough and London.

In terms of how it was shown in the timetable I have no idea. I would guess that it was manually added to the sectional timings lifted from the timing books?

 

[30907]

The concept of ‘recovery time’ was I believe a BR invention in the 1950s; but it was applied in a very ham-fisted manner, for instance all Up expresses bound for Kings Cross having 18 minutes of recovery time between Peterborough and London.

The other early user was the LMR, again using a "lump sum" approach - I recall Cecil J Allen's regular complaints WRT to train timing!
In the 60s/70s it was split up into smaller chunks.

In terms of how it was shown in the timetable I have no idea.

The earliest I can recall were the number inside a rectangular box.

 

[Magdalia]

The earliest I can recall were the number inside a rectangular box.

The oldest WTT in my collection is 1958 and it already has these for recovery time.

Separate times for pathing requirements, shown inside a circle, were introduced in 1973.

 

[Henffordd]

The oldest WTT in my collection is 958 sand it already has these for recovery time.

Separate times for pathing requirements, shown inside a circle, were introduced in 1973.

Interesting typo! Perhaps the invention of Ethelred the Unready?

 

[Magdalia]

Interesting typo! Perhaps the invention of Ethelred the Unready?

Ethelred the Unready would be a suitable inventor of recovery time. With a name like that he would have needed it.

Typo corrected.

 

[Wilts Wanderer]

The oldest WTT in my collection is 1958 and it already has these for recovery time.

Separate times for pathing requirements, shown inside a circle, were introduced in 1973.

In terms of the ‘lump sum allowances’, was it shown in one location rather than being spread out across the section? That must have looked very bizarre on the train graph.

 

[hexagon789]

The Practice & Performance column of the Railway Magazine makes reference to recovery allowances.

In the 1930s, it appears the French had them in the modern sense, spread throughout a scheulde but they were not expressly marked as such more as inflating times between stations by a min or two.

The Americans in this period seem to have taken the approach of grossly inflating time between the last pair of stations in the same period.

In Britain, while there is reference to easy and to tight timings; the first explicit reference I can find to time recovery allowances appears post-war.

 

[Senex]

The Practice & Performance column of the Railway Magazine makes reference to recovery allowances.

In the 1930s, it appears the French had them in the modern sense, spread throughout a scheulde but they were not expressly marked as such more as inflating times between stations by a min or two.

The Americans in this period seem to have taken the approach of grossly inflating time between the last pair of stations in the same period.

In Britain, while there is reference to easy and to tight timings; the first explicit reference I can find to time recovery allowances appears post-war.

The German practice too was a small inflation of all the sectional times rather than lumps of time in certain sections only. I wonder if this was the common mainland European practice. I thought it was also what the Southern Railway and then the Southern Region did here. I'm sure I remember quite a long debate about in the periodicals in the early 60s (?), I think even with a contribution from Gerry Fiennes. As to running to time, I'm sure I recall Cecil J Allen more than once referring to French drivers' pride in keeping exactly to their scheduled times rather than trying their best to run ahead of time even at the risk of signal checks.

 

[Wilts Wanderer]

The German practice too was a small inflation of all the sectional times rather than lumps of time in certain sections only. I wonder if this was the common mainland European practice. I thought it was also what the Southern Railway and then the Southern Region did here. I'm sure I remember quite a long debate about in the periodicals in the early 60s (?), I think even with a contribution from Gerry Fiennes. As to running to time, I'm sure I recall Cecil J Allen more than once referring to French drivers' pride in keeping exactly to their scheduled times rather than trying their best to run ahead of time even at the risk of signal checks.

Perfectly adhering to booked timings whilst maximising efficiency in fuel usage is arguably the highest skill level a crew can demonstrate. Heavy / high speed working can then be drawn on as a resource to use when trying to recover time.

 

[Bald Rick]

I thought it was also what the Southern Railway and then the Southern Region did here.

Still do.

 

[Wilts Wanderer]

Still do.

Not strictly true, the Southern region (NR’s Wessex, Sussex & South East Routes) uplift all SRTs by 5% in lieu of engineering allowance, not performance recovery.