Simplified acceleration/deceleration rates - historical traction

[Blade Fisher]

I have a slight interest in performance of trains in the 1960's to 1980', to me the heritage diesel era and wondered if there was any generic info available on such acceleration/deceleration rates under normal service conditions. Cl 20/25/26/27/33/35/37/40/45/47/52/55 that sort of stuff

As a total unscientific rule of thumb when I used to travel from Reading to Lymington every fortnight I think it was this way round braking seemed to be twice as fast as acceleration so say it would take a minute to stop from 60mph but take two mins to get there. Now obviously it wasn't a race track and there were often junctions to navigate, usually at 20mph but I seem to recall it was something like this. Any help gratefully received or whatever from the sim boys too.

 

[coppercapped]

I have a slight interest in performance of trains in the 1960's to 1980', to me the heritage diesel era and wondered if there was any generic info available on such acceleration/deceleration rates under normal service conditions. Cl 20/25/26/27/33/35/37/40/45/47/52/55 that sort of stuff

As a total unscientific rule of thumb when I used to travel from Reading to Lymington every fortnight I think it was this way round braking seemed to be twice as fast as acceleration so say it would take a minute to stop from 60mph but take two mins to get there. Now obviously it wasn't a race track and there were often junctions to navigate, usually at 20mph but I seem to recall it was something like this. Any help gratefully received or whatever from the sim boys too.

Isaac Newton tells us that acceleration is proportional to the accelerating force divided by the mass of the object being accelerated.

All the vehicles you mention are locomotives which means that the acceleration rate is determined by the total mass, that is locomotive plus coaches, of the train and by the tractive effort which can be exerted by the locomotive. This means that the acceleration of, say, a Class 47 varies depending on whether it is hauling 5 coaches or fifteen — the heavier the load the lower the acceleration.

There may well be some data available for individual test runs where time/speed curves were plotted, BR used to publish test reports on some locomotives but this was all a generation and more before the internet so I doubt whether there are any on-line sources. (Though I admit I haven't looked to any extent).

Braking was more consistent as each passenger vehicle came with its own brakes and therefore the brake force/unit mass was more consistent. This is one of the advantages of multiple units — the power to mass ratio remains constant, and therefore the acceleration, however many units are coupled together.

 

[Blade Fisher]

Isaac Newton tells us that acceleration is proportional to the accelerating force divided by the mass of the object being accelerated.

All the vehicles you mention are locomotives which means that the acceleration rate is determined by the total mass, that is locomotive plus coaches, of the train and by the tractive effort which can be exerted by the locomotive. This means that the acceleration of, say, a Class 47 varies depending on whether it is hauling 5 coaches or fifteen — the heavier the load the lower the acceleration.

There may well be some data available for individual test runs where time/speed curves were plotted, BR used to publish test reports on some locomotives but this was all a generation and more before the internet so I doubt whether there are any on-line sources. (Though I admit I haven't looked to any extent).

Braking was more consistent as each passenger vehicle came with its own brakes and therefore the brake force/unit mass was more consistent. This is one of the advantages of multiple units — the power to mass ratio remains constant, and therefore the acceleration, however many units are coupled together.

yep know abt f=ma etc. I was assuming a standard 315 TL

 

[Harpo]

This is one of the advantages of multiple units — the power to mass ratio remains constant, and therefore the acceleration, however many units are coupled together.

Possibly true of MUs if set up to deliver constant performance levels but without that a longer rake will be faster as there is only ever one front end resistance. 12 cars of mk1 EMU was always faster than 1x4 of the same type for example.

On braking loco-hauled passenger stock, retardation improves with longer formations hence the speed restrictions that apply to light engines and short formations.

 

[Belperpete]

For S&T, we had a number of braking curves used to determine signal spacing, the W curve, the passenger curve and the SR curve. However, these were an amalgam of various things, including allowances for driver's reaction time, brake reaction time, etc. The W curve as I recall allowed for the worst cases of both passenger and freight. The SR emu curve allowed for both epb and pure vacuum braking, as at that time there was still some of the older non-epb stock still in service.

We rarely needed to know acceleration rates. For headway purposes I seem to recall that we used a set acceleration rate, unfortunately I can't offhand recall what it was, let alone how it was derived. For level crossings, if there is a signal close to an automatic crossing, you need to know how fast a train can accelerate from that signal when it clears up from red, to reach the crossing. For that we used curves based on a light class 47, which I understand were obtained from a number of test runs. I presume that this was taken to be the lightest, most powerful train around at the time.

== Doublepost prevention - post automatically merged: 20 Jul 2025 ==

On braking loco-hauled passenger stock, retardation improves with longer formations hence the speed restrictions that apply to light engines and short formations.

With long formations of pure vacuum or air braked stock, there can however be a significant delay in the brake application reaching the rear of the train.

 

[Magdalia]

Isaac Newton tells us that acceleration is proportional to the accelerating force divided by the mass of the object being accelerated.

This is one part of the equation, but there are 2 other significant parts.

The first is gradient: compared with level track a train will accelerate more slowly going uphill and more rapidly going downhill. Conversely, a train will decelerate more rapidly going uphill and more slowly going downhill.

The other is resistance to motion. The biggest part of this is front end resistance hence this:

Possibly true of MUs if set up to deliver constant performance levels but without that a longer rake will be faster as there is only ever one front end resistance. 12 cars of mk1 EMU was always faster than 1x4 of the same type for example.

But, for hauled trains, rolling stock had different resistances. Part of that was the different aerodynamics of MarkI, MarkII and MarkIII coaches (mixed rakes were in the too difficult pile) and different rolling resistances of different bogies.

Resistances to motion could also be affected by wind direction and speed, and particularly by tunnels.

So far we have only considered the theory, even more important are the practical challenges of collecting usable data on a comparable basis. In the period that you are talking about, the professional engineers could use a dynamometer car for measurement, but the amateur enthusiast only had manual stopwatches. Having also done manual timing at competitive sport, I know that there is significant measurement error and bias in manual timing.

The much more basic technology also applied to locomotive maintenance: there were no electronic engine management systems and key components such as fuel injectors and turbochargers would be adjusted by depot engineers. As a result there would be considerable variation in performance between members of the same class.

I was assuming a standard 315 TL

On most routes there was no such thing as a standard trailing load. Except where governed by platform length restrictions, fixed formations only really started with the HSTs then spread to hauled stock. To give one example, in the 1970s the 2 Cambridge Buffet Express sets were 8 cars, but every weekday afternoon 2 extra coaches would be attached to the 1530 from Cambridge, then removed again when the set got back to Cambridge on the 1714 from Kings Cross.

Another factor where there was much more variation in those days was driving technique, and this had most impact at starts and stops. Remember that trainee drivers learned their techniques from more senior colleagues, on the job, not on a simulator. In particular drivers would not all learn the same braking points.

Taking all of these together, valid comparisons required elimination of as many sources of error as possible. For this reason trains running at a steady speed on a steady gradient offered the least unreliable comparisons.

 

[Blade Fisher]

This is one part of the equation, but there are 2 other significant parts.

The first is gradient: compared with level track a train will accelerate more slowly going uphill and more rapidly going downhill. Conversely, a train will decelerate more rapidly going uphill and more slowly going downhill.

The other is resistance to motion. The biggest part of this is front end resistance hence this:


But, for hauled trains, rolling stock had different resistances. Part of that was the different aerodynamics of MarkI, MarkII and MarkIII coaches (mixed rakes were in the too difficult pile) and different rolling resistances of different bogies.

Resistances to motion could also be affected by wind direction and speed, and particularly by tunnels.

So far we have only considered the theory, even more important are the practical challenges of collecting usable data on a comparable basis. In the period that you are talking about, the professional engineers could use a dynamometer car for measurement, but the amateur enthusiast only had manual stopwatches. Having also done manual timing at competitive sport, I know that there is significant measurement error and bias in manual timing.

The much more basic technology also applied to locomotive maintenance: there were no electronic engine management systems and key components such as fuel injectors and turbochargers would be adjusted by depot engineers. As a result there would be considerable variation in performance between members of the same class.


On most routes there was no such thing as a standard trailing load. Except where governed by platform length restrictions, fixed formations only really started with the HSTs then spread to hauled stock. To give one example, in the 1970s the 2 Cambridge Buffet Express sets were 8 cars, but every weekday afternoon 2 extra coaches would be attached to the 1530 from Cambridge, then removed again when the set got back to Cambridge on the 1714 from Kings Cross.

Another factor where there was much more variation in those days was driving technique, and this had most impact at starts and stops. Remember that trainee drivers learned their techniques from more senior colleagues, on the job, not on a simulator. In particular drivers would not all learn the same braking points.

Taking all of these together, valid comparisons required elimination of as many sources of error as possible. For this reason trains running at a steady speed on a steady gradient offered the least unreliable comparisons.

Oh dear.

The problem with this site is that posters take you too literally at times.

When I said standard 315 the implication was loco+9 carriages = TL 315. I wasnt assuming anything was standard! Otherwise we wouldnt have had umpteen different timing loads.

For the avoidance of doubt what was the minimum loco hauled trailing load - 3 carriages?? 105tns? and the longest? When you consider that there might be say for argument 10 loco hauled carriage trailing loads and each point to point has 4 variations that means 40 for pax loco hauled trains alone. Must have been a big help with computerisation.

 

[Magdalia]

Oh dear.

The problem with this site is that posters take you too literally at times.

I can only go on what you have written.

Any help gratefully received

I am trying to be helpful, but you don't seem very grateful!

If I was at work, then the answer would have been:

"The information is not available in the form requested".

For the avoidance of doubt what was the minimum loco hauled trailing load - 3 carriages??

I can think of a few examples of 2 carriage trains. One of the most well known was the Saturdays 2050 Carlisle-Perth, hauled by an A/C electric: the acceleration was phenomenal but the braking for the Lockerbie stop was a bit scary!

and the longest?

If you read the concurrent discussion about sleeper trains you will learn that many were 16 carriages.

When you consider that there might be say for argument 10 loco hauled carriage trailing loads and each point to point has 4 variations that means 40 for pax loco hauled trains alone.

Almost. The 1976 ECML WTT has every timing load D210-D455 for daytime trains, plus D560 for some of the sleepers. Each would need separate Type 5 and Type 4 timings, at the lighter end there would be Type 2 timings too. I'm not sure if the ECML had separate timings for class 47 and class 40/46.

 

[ac6000cw]

The problem with this site is that posters take you too literally at times.

There's a lot of very knowledgeable people on this forum who might easily take your question literally - if you are quoting something as an example then say so, it doesn't take much effort to type 'e.g.' (and moaning at people when you're asking for help isn't a great idea).

For the avoidance of doubt what was the minimum loco hauled trailing load - 3 carriages??

In the low season (tourist-wise) I suspect some of the West Highland line trains might have been that short (and in the 1970s in the West Midlands I remember regularly seeing a 3-carriage loco-hauled train that was basically a daytime parcels working with a passenger coach included). Absolute minimum it could possibly be is one brake vehicle with passenger accommodation e.g. a BSO/BSK/BCK, but two vehicles would be a more likely minimum i.e. a coach plus a brake vehicle, e.g. a TSO + BSO. Minimum brake force requirements are also a factor in very short loco-hauled formations e.g. limiting the maximum train speed, but some secondary lines have low maximum speeds anyway.

I can think of a few examples of 2 carriage trains. One of the most well known was the Saturdays 2050 Carlisle-Perth, hauled by an A/C electric: the acceleration was phenomenal but the braking for the Lockerbie stop was a bit scary!

I can well imagine (brings back memories of a cl. 86 hauled excursion from Birmingham to Edinburgh in the mid-1970s - last passenger stop was Wolverhampton, and in between crew changes at Crewe and Carlisle it went like the proverbial, arriving at least 30 minutes early at Carstairs...)

I have a slight interest in performance of trains in the 1960's to 1980', to me the heritage diesel era and wondered if there was any generic info available on such acceleration/deceleration rates under normal service conditions. Cl 20/25/26/27/33/35/37/40/45/47/52/55 that sort of stuf

yep know abt f=ma etc.

As you know how to calculate it, then all you need is the low-speed (adhesion limited) tractive effort data for the loco and the train weight to derive the maximum low-speed acceleration (ignoring rolling resistance and gradients). Once the speed is high enough that the loco is on the power-limited part of the TE curve, then use the power-at-rail to derive it at a specific velocity i.e. a=P/(m*v).

See https://www.railtechnical.com/moderisation-plan-diesels for some 'Modernisation Plan' era diesel loco TE and power at rail graphs (in lbf and hp units) e.g. class 47: https://www.railtechnical.com/class-47-48-diesel-electric

 

[Blade Fisher]

I can only go on what you have written.


I am trying to be helpful, but you don't seem very grateful!

If I was at work, then the answer would have been:

"The information is not available in the form requested".


I can think of a few examples of 2 carriage trains. One of the most well known was the Saturdays 2050 Carlisle-Perth, hauled by an A/C electric: the acceleration was phenomenal but the braking for the Lockerbie stop was a bit scary!


If you read the concurrent discussion about sleeper trains you will learn that many were 16 carriages.



Almost. The 1976 ECML WTT has every timing load D210-D455 for daytime trains, plus D560 for some of the sleepers. Each would need separate Type 5 and Type 4 timings, at the lighter end there would be Type 2 timings too. I'm not sure if the ECML had separate timings for class 47 and class 40/46.

Well since posting my lower limit is 3 and upper limit is 19. I think the former was a Leeds-Derby SO service and the latter St Austell-Crewe motorail

== Doublepost prevention - post automatically merged: 21 Jul 2025 ==

There's a lot of very knowledgeable people on this forum who might easily take your question literally - if you are quoting something as an example then say so, it doesn't take much effort to type 'e.g.' (and moaning at people when you're asking for help isn't a great idea).


In the low season (tourist-wise) I suspect some of the West Highland line trains might have been that short (and in the 1970s in the West Midlands I remember regularly seeing a 3-carriage loco-hauled train that was basically a daytime parcels working with a passenger coach included). Absolute minimum it could possibly be is one brake vehicle with passenger accommodation e.g. a BSO/BSK/BCK, but two vehicles would be a more likely minimum i.e. a coach plus a brake vehicle, e.g. a TSO + BSO. Minimum brake force requirements are also a factor in very short loco-hauled formations e.g. limiting the maximum train speed, but some secondary lines have low maximum speeds anyway.


I can well imagine (brings back memories of a cl. 86 hauled excursion from Birmingham to Edinburgh in the mid-1970s - last passenger stop was Wolverhampton, and in between crew changes at Crewe and Carlisle it went like the proverbial, arriving at least 30 minutes early at Carstairs...)



As you know how to calculate it, then all you need is the low-speed (adhesion limited) tractive effort data for the loco and the train weight to derive the maximum low-speed acceleration (ignoring rolling resistance and gradients). Once the speed is high enough that the loco is on the power-limited part of the TE curve, then use the power-at-rail to derive it at a specific velocity i.e. a=P/(m*v).

See https://www.railtechnical.com/moderisation-plan-diesels for some 'Modernisation Plan' era diesel loco TE and power at rail graphs (in lbf and hp units) e.g. class 47: https://www.railtechnical.com/class-47-48-diesel-electric

Well thanks for the fullsome reply. Unfortunately I am none the wiser and I have sent you a private message.

Considering as you say there are some very knowledgeable people alas this one is a mixture of too technical and baffled the appropriate brains.

 

[ac6000cw]

The problem is that what you might think is a simple question is actually hard to provide a simple answer to. Part of the problem is that beyond quite low speeds, a typical 1960s diesel loco is operating in the 'power limited' region of its tractive effort curve, where the acceleration decreases as the speed increases. This makes the maths a bit complicated in terms of working out how long it would take an accelerating train to climb a gradient of specified length.

If you're interested, 'British Rail Motive Power Performance' by David N. Clough & Martin Beckett (1988), has examples of real-world 1960s/70s diesel loco, electric loco, DMU and EMU performance logs, plus Chapter 3 'Performance Assessment' covers the maths for theoretical calculations (albeit in old British, non-SI units), and is available used for only a few pounds (I have a copy I bought for £2 recently).

 

[Blade Fisher]

The problem is that what you might think is a simple question is actually hard to provide a simple answer to. Part of the problem is that beyond quite low speeds, a typical 1960s diesel loco is operating in the 'power limited' region of its tractive effort curve, where the acceleration decreases as the speed increases. This makes the maths a bit complicated in terms of working out how long it would take an accelerating train to climb a gradient of specified length.

If you're interested, 'British Rail Motive Power Performance' by David N. Clough & Martin Beckett (1988), has examples of real-world 1960s/70s diesel loco, electric loco, DMU and EMU performance logs, plus Chapter 3 'Performance Assessment' covers the maths for theoretical calculations (albeit in old British, non-SI units), and is available used for only a few pounds (I have a copy I bought for £2 recently).

Hi look thanks.

I started playing around with a spreadsheet today on the first bit and I appreciate the TE curves. Am not sure if I might not have this book buried away in 'the attic' and was going to hunt for it tomorrow. Because it is a curve (the TE) I wonder if anyone has done the grunt work already and all you'd need to do is plug in a few variables such as loco type, trailing load, grade etc. This isnt some cheap way to do consultancy, man way beyond that, its a sort of nostalgic play time. I am retired now and not in the best of health so am indulging in a bit of what if scenario. For the most part I am interested in routes long gone !

I have always been interested in operational planning of transport and had it not been for the most dreadful of accidents would probably gone on into the shipping world - which was a first love, but fate intervened and my second choice, the railways, didnt materialise either for many moons, so I ended up in road freight and passenger.

I have always found the railway industry very cliquey, probably because for many years the public had this enduring love for them and some thought they knew how to operate them and I suspect those in the know sort of resented that. It is like seafaring and no doubt the airline industries very very specific with its own language and issues but nevertheless when I finally entered it it was quite noticeable if you weren't ex BR/Railtrack etc.

Though a bit off thread I get exercised over the reporting of shipping issues and the idiocy of reporting even by the BBC just sends me Meldrew like into orbit. Still can't get over the classic earlier this year when the Stena Immaculate was reported to be carrying x barrels of crude oil when it was struck at anchor by the Solong. Silly buggars thought that literally there were barrels aboard the ship (perhaps watching too much Pirates of the Carribbean) forgetting of course that the US measures oil in barrels. Deary me.

I shall come back to you again.

Richard

 

[Magdalia]

I started playing around with a spreadsheet today on the first bit and I appreciate the TE curves.

I studied Maths and Statistics to degree level, then worked in the field of economics and statistics. My first encounters with spreadsheets were in the late 1980s: at work we had SuperCalc on an early desktop PC that was shared in a team of 10-12 people.

I wonder if anyone has done the grunt work already and all you'd need to do is plug in a few variables such as loco type, trailing load, grade etc.

In the era you are talking about, few if any people had access to spreadsheets. In the 1980s they had pocket electronic calculators, up to quite late in the 1970s they would have been using slide rules.

I remember trying to set up a SuperCalc spreadsheet one lunch hour, probably during a relatively quiet summer day in 1988 or 1989 when a lot of the team were on holiday.

The big problem with doing a spreadsheet retrospectively is the data entry. I can type numbers quickly on a proper keyboard number pad, but the data entry is nevertheless a time consuming task. One day I might get round to it, but there are other similar tasks nearer to the top of the priority list.

 

[Belperpete]

Well since posting my lower limit is 3 and upper limit is 19. I think the former was a Leeds-Derby SO service and the latter St Austell-Crewe motorail

== Doublepost prevention - post automatically merged: 21 Jul 2025 ==


Well thanks for the fullsome reply. Unfortunately I am none the wiser and I have sent you a private message.

Considering as you say there are some very knowledgeable people alas this one is a mixture of too technical and baffled the appropriate brains.

You seem to keep moving the goal posts. Your initial post asked a very vague question about performance, and said nothing about train lengths, then you mentioned 315TL, and now you are talking about anything between 3 and 19 coaches. I suspect that you don't really know what you are asking for, which is why you aren't understanding the replies. I am certainly none the wiser about what exactly it is that you want. I suspect that you are after a fairly simplistic answer to something that is actually very complex.

As others have already pointed out, train performance is a combination of the performance of the particular locomotive and the particular rolling stock it is hauling, affected by things like the gradient and train loading. There are a great number of variables involved. Just to take one example, if the gradient is sufficient falling, you don't actually need any loco power for a train to accelerate. And likewise with a rising gradient, you might not actually need to apply any braking force to stop it. Good luck with producing a spreadsheet that can take all these factors into account.

Back in the 1970s, before computers, all most people would have wanted to know is what load a particular locomotive could haul to meet section timings, and did it have acceptable braking.

== Doublepost prevention - post automatically merged: 22 Jul 2025 ==

The big problem with doing a spreadsheet retrospectively is the data entry. I can type numbers quickly on a proper keyboard number pad, but the data entry is nevertheless a time consuming task. One day I might get round to it, but there are other similar tasks nearer to the top of the priority list.

Spreadsheets are of most use where most of the figures are produced by calculation, not by manual entry. If you are having to fill in all the figures manually, it is really just a table.

 

[Blade Fisher]

You seem to keep moving the goal posts. Your initial post asked a very vague question about performance, and said nothing about train lengths, then you mentioned 315TL, and now you are talking about anything between 3 and 19 coaches. I suspect that you don't really know what you are asking for, which is why you aren't understanding the replies. I am certainly none the wiser about what exactly it is that you want. I suspect that you are after a fairly simplistic answer to something that is actually very complex.

As others have already pointed out, train performance is a combination of the performance of the particular locomotive and the particular rolling stock it is hauling, affected by things like the gradient and train loading. There are a great number of variables involved. Just to take one example, if the gradient is sufficient falling, you don't actually need any loco power for a train to accelerate. And likewise with a rising gradient, you might not actually need to apply any braking force to stop it. Good luck with producing a spreadsheet that can take all these factors into account.

Back in the 1970s, before computers, all most people would have wanted to know is what load a particular locomotive could haul to meet section timings, and did it have acceptable braking.

== Doublepost prevention - post automatically merged: 22 Jul 2025 ==


Spreadsheets are of most use where most of the figures are produced by calculation, not by manual entry. If you are having to fill in all the figures manually, it is really just a table.

I am not moving the goalposts I am responding to the replies. I would have thought that was a tad obvious!

What I started off with was a simple 'back of a fag packet' question. It is like asking how long would it take to travel from Carlisle to Southampton in a car, and a boafp answer from me would be 6hrs. Why? Because I have done it so many times and it is good average, but in detail?? Well you'd have to split the journey up into sections because of expected traffic demand/time of day also there would be route options is it M6/M5/A419 or is it M6/M42/M40/A34 and all the other variations in between.

I have already responded to the issue of trailing train weight (many pax trains were around 9 carriages hence the 315TL) and the coaches were in response to another thread on sleepers so please dont confuse matters in trying to score points. In summary the debate shifted as no one was capable of providing a boafp answer. I know technically it's complicated, we wouldnt have RailSys et al if it was simple would we. And you are responding to someone who has been part of the design team for a few projects both pax and freight in the UK and overseas.

It doesnt help that the nature of threads means you get answers/comments to thread no: 8 after thread no: 27 when things have moved on. One of the downsides of Forums I suppose, but I appreciate the response.

 

[Harpo]

train performance is a combination of the performance of the particular locomotive and the particular rolling stock it is hauling, affected by things like the gradient and train loading.

Before current driving-by-numbers uniformity when hard acceleration and braking were considered a skill, driver handling techniques were one of the biggest variables.

 

[Belperpete]

I am not moving the goalposts I am responding to the replies. I would have thought that was a tad obvious!

What I started off with was a simple 'back of a fag packet' question. It is like asking how long would it take to travel from Carlisle to Southampton in a car, and a boafp answer from me would be 6hrs.

I am tempted to reply that the answer to your question is "42". That is how the computer in Hitchhikers eventually responded when asked to give a very simple answer to a question that is actually very complex.

The old adage "ask a silly question and you will get a silly answer" would seem to apply here. Rather than blaming others for not giving the answers that you wanted, I suggest that you think about the question you asked. You may have thought that you were asking a simple boafp question, but that isn't what you actually asked. You asked a question that was so vague as to be almost meaningless.

If you asked me how long it would take to drive to Southampton, I wouldn't just reply 6 hours. I would want more information. If you were going to catch the last ferry, for example, my answer may be very different.

You didn't give any clue about why you wanted the information, what you intended doing with it, or any clue about how detailed you wanted the answers to be. And you still haven't! In fact, your subsequent responses have just mudied the waters even further, with talk of wide variations in train length. All I currently know is that you are entering figures in a spreadsheet of some kind. Is that spreadsheet going to take account of real life factors like train type, length and loading, gradient, etc that significantly impact performance? Currently only you know.

== Doublepost prevention - post automatically merged: 22 Jul 2025 ==

In the low season (tourist-wise) I suspect some of the West Highland line trains might have been that short (and in the 1970s in the West Midlands I remember regularly seeing a 3-carriage loco-hauled train that was basically a daytime parcels working with a passenger coach included). Absolute minimum it could possibly be is one brake vehicle with passenger accommodation e.g. a BSO/BSK/BCK, but two vehicles would be a more likely minimum i.e. a coach plus a brake vehicle, e.g. a TSO + BSO. Minimum brake force requirements are also a factor in very short loco-hauled formations e.g. limiting the maximum train speed, but some secondary lines have low maximum speeds anyway.

I have a vague recollection that there was (maybe still is), a minimum number of vehicles that you can detach, and still rely on the vacuum brake holding them? This may have had a bearing on practical minimum train lengths?

 

[Magdalia]

Spreadsheets are of most use where most of the figures are produced by calculation, not by manual entry. If you are having to fill in all the figures manually, it is really just a table.

Spreadsheets are where the output is produced by calculation, but that calculation requires raw data, and lots of it. In this case lots of raw data on places, distances and times for large numbers of trains. That goes into a table, from which what is required is calculated. But unless that raw data is already in a digital format, someone has got to do typing.

 

[Blade Fisher]

I am tempted to reply that the answer to your question is "42". That is how the computer in Hitchhikers eventually responded when asked to give a very simple answer to a question that is actually very complex.

The old adage "ask a silly question and you will get a silly answer" would seem to apply here. Rather than blaming others for not giving the answers that you wanted, I suggest that you think about the question you asked. You may have thought that you were asking a simple boafp question, but that isn't what you actually asked. You asked a question that was so vague as to be almost meaningless.

If you asked me how long it would take to drive to Southampton, I wouldn't just reply 6 hours. I would want more information. If you were going to catch the last ferry, for example, my answer may be very different.

You didn't give any clue about why you wanted the information, what you intended doing with it, or any clue about how detailed you wanted the answers to be. And you still haven't! In fact, your subsequent responses have just mudied the waters even further, with talk of wide variations in train length. All I currently know is that you are entering figures in a spreadsheet of some kind. Is that spreadsheet going to take account of real life factors like train type, length and loading, gradient, etc that significantly impact performance? Currently only you know.

== Doublepost prevention - post automatically merged: 22 Jul 2025 ==


I have a vague recollection that there was (maybe still is), a minimum number of vehicles that you can detach, and still rely on the vacuum brake holding them? This may have had a bearing on practical minimum train lengths?

Great!

== Doublepost prevention - post automatically merged: 22 Jul 2025 ==

Before current driving-by-numbers uniformity when hard acceleration and braking were considered a skill, driver handling techniques were one of the biggest variables.

I wonder how they model that !

 

[Harpo]

I wonder how they model that !

Driver variability was ‘modelled’ by knowing who was/wasn’t good. Managers knew who would lose time (often an overtime ploy on freight) and who would make it up. It was also recognised that the presence of an inspector had a negative impact.

Interestingly, of steam, older friends said they didn’t follow the loco, they followed the driver and knew who’d be up for a ten bob challenge on speeds.

 

[Blade Fisher]

Driver variability was ‘modelled’ by knowing who was/wasn’t good. Managers knew who would lose time (often an overtime ploy on freight) and who would make it up. It was also recognised that the presence of an inspector had a negative impact.

Interestingly, of steam, older friends said they didn’t follow the loco, they followed the driver and knew who’d be up for a ten bob challenge on speeds.

Yes can believe that ! Are you Newport Gwent/Salop/IoW or Essex?

 

[SteveB000]

I have access to a simulation program that allows me to simulate acceleration for most types of historical traction