Timetable Graphs, Geography, and Motive Power

[Nagora]

I recently discovered timetabling graphs and I have a question or two. Mainly this relates to the old days when they were done by hand as I suspect the answers today are "oh, the computer worries about that".

If I'm graphing a timetable then as I understand it I have horizontal lines representing stretches of track between junctions and stations and the angle of the line I draw represents the speed of the train.

The first question is: to decide the speed of the train I need to know the gradients along that track but none of the examples I've found online have mentioned that and some photographs I've seen of the pencil and paper days didn't seem to show that either. Was this simply used "off camera" before the lines are drawn?

The related question is: if I know the horsepower and TE of the locomotive unit(s) and the gradient then I can clearly make a good stab at calculating the average speed of a particular train. Why, then, is it so hard to find HP values for the days of steam? Surely this information should be in every Ian Allan book beside the TE, boiler pressure etc.? Did the companies keep the values secret or something? TE will tell me if the train will go up a hill, but only HP will tell me how fast.

I've wondered for a long time about the lack of HP values from steam days and I've occasionally seen comments online to the effect that HP is not important or "just marketing". Yet it seems a vital statistic for drawing up timetables. What gives?

 

[800002]

If I'm graphing a timetable then as I understand it I have horizontal lines representing stretches of track between junctions and stations and the angle of the line I draw represents the speed of the train

I don't think the line drawn, between the twospecific points equates to speed. It is the time taken to traverse the two points.
If the train is starting point A from a stand, the line drawn to point B will be shallower in angle than it would be I'd the train was starting point A running (in motion).
The bottom axis is time
The verticle axis is distance (specifically a graduated distance betweens concecutive points along the route). As the points are not equidistant apart, the scale of distance changes between each point.

Between each set of points, the Sectional Running Time (SRT) for each type of traction / consist is used.
The SRT takes into account things like you've mentioned, ie: Gradient; traction profile, weight etc, which is how we know how long it should take to get from A-B and beyond.
I really hope that makes sense, and helps.

The first question is: to decide the speed of the train I need to know the gradients along that track but none of the examples I've found online have mentioned that and some photographs I've seen of the pencil and paper days didn't seem to show that either. Was this simply used "off camera" before the lines are drawn?

I honestly think the pencil and paper guys knew a hell of alot more then, than the computer guys do today. Yeah, the computer draws the line today but it's still the humans who gather (and interpret) the data which gets input into the computer.

I think these days SRTs are generated by plonking train on track and seeing what it can actually do!

 

[edwin_m]

The Sectional Running Times can be generated by running an actual train but these days are more likely to be produced by simulation software. This has the advantage that the timetable can be prepared long before delivery of the actual trains or completion of the line improvements it takes into account.

 

[yorkie]

The related question is: if I know the horsepower and TE of the locomotive unit(s) and the gradient then I can clearly make a good stab at calculating the average speed of a particular train.

The maximum power is not the only factor that determines the speed of the train; the train weight is obviously a factor, along with the tractive effort, rail conditions etc. The train length will also play a part (you cannot accelerate away from speed restrictions until the rear of the train is clear of the restriction).

See this post by D6700 for some information about timing loads and calculating sectional running times.

Perhaps someone like @Oscar @D6700 @Ianno87 @ChiefPlanner @MidnightFlyer might be able to assist in answering your questions.

 

[800002]

The Sectional Running Times can be generated by running an actual train but these days are more likely to be produced by simulation software.

That is true - the simulation comes first; confirmation in physical terms second. Sorry, didn't mean to mislead.

See this post by D6700 for some information about timing loads and calculating sectional running times.

That is an excellent post, thanks for sharing it

Ofcourse, certain NR train planners have the ability to simply input whatever time figure they like (in half minute incriments) into TPS when an SRT doesn't exist.

 

[306024]

..........I honestly think the pencil and paper guys knew a hell of alot more then, than the computer guys do today. Yeah, the computer draws the line today but it's still the humans who gather (and interpret) the data which gets input into the computer.

I think these days SRTs are generated by plonking train on track and seeing what it can actually do!

As a pencil and paper guy I’d agree. The old timing offices used to have special sloping desks, rolls of graph paper, coloured pencils, a rubber and the obligatory cardigan. Drawing the graph by hand meant the brain assimilated the information as you went along, computed generated graphs are obviously much quicker but take a lot of studying to get your knowledge to the same level of detail.

As for computer generated SRTs, these can be calculated for the geography and traction characteristics of the route, and are used for timetable planning. However the drawbacks are that they tend to be quite optimistic and rather theoretical. Plonking a train on the track is done but provides limited data, and requires a clear run for accurate information.

 

[800002]

and the obligatory cardigan

Surely, this is the most important component?!

However the drawbacks are that they tend to be quite optimistic and rather theoretical.

Indeed - but theoritical is a good place to start. Gives the team in charge in getting it into service something to work with initially

Plonking a train on the track is done but provides limited data, and requires a clear run for accurate information.

Two points here: Gotta prove the theory of the simulation and
Difficult, but doable - good planning and comms with the OPs staff, mainly signallers, is advised.
It's easier if it's a single TOC on the rails as they can better accomodate a speed test run than if there's multiple TOCs to plan around.

As an aside... how on earth did you ascimilate an entire set of SRTs??!!

 

[306024]

It’s not the SRTs that you get in your brain (although over the years the more frequently used ones tend to stick). There were lots of tables of SRTs to refer to, anything from a 31 on load 4 to a 47 on load 11.

It is the junction margins and clashes with other trains that you pick up as you go along. Today’s software highlights that for you but it is all in your face at once. The brain can only take in so much information in one go. Today’s computer generation have a head start on us traditionalists, but the job has become much more theoretical and contractual. The best way to learn though is to get in the cab with an experienced driver who doesn’t mind someone with a stopwatch.

 

[800002]

It’s not the SRTs that you get in your brain (although over the years the more frequently used ones tend to stick). There were lots of tables of SRTs to refer to, anything from a 31 on load 4 to a 47 on load 11.

It is the junction margins and clashes with other trains that you pick up as you go along. Today’s software highlights that for you but it is all in your face at once. The brain can only take in so much information in one go. Today’s computer generation have a head start on us traditionalists, but the job has become much more theoretical and contractual. The best way to learn though is to get in the cab with an experienced driver who doesn’t mind someone with a stopwatch.

Ahh, you still had tables of infoto refer to and such. For some reason I didn't consider that.
Agreed - the rules (TPRs) do take a littlewhile to embed into the brain and you get used to them and just see when it's not correct.
The new aTune software tells you when trains are in conflict with the rules, as defined by the manual input into the system, but I don't think the TPS programme does.

It's all about getting it compliant on paper (rather, on screen) than having a pratical and knowledgeable input - which is abit sad and annoying.
Cab-rides are great learning oportunities - agreed.

 

[43074]

It's all about getting it compliant on paper (rather, on screen) than having a pratical and knowledgeable input - which is abit sad and annoying.

I think anyone can produce a timetable with no conflicts etc in software like Attune - but the skill lies in being able to translate what's on paper to something that will work well on the ground, and to do that you need the knowledge and experience. There are also plenty of examples of rules which don't appear in the TPRs, such as how to plan arrivals and departures at depots, which similarly gets passed down by experience. So although the processes might be far more computerised they still rely on good planners using the software to get a decent end result.

 

[Nagora]

The Sectional Running Times can be generated by running an actual train

That's just cheating

Thanks for the answers, everyone.

 

[The Planner]

As an aside... how on earth did you ascimilate an entire set of SRTs??!!

You model them, pretty much in Railsys now. Back in the good old days it was done by a system called VISION (still about I think) which fed in to the TRATIM tables which were tables of SRTs between timing points for a myriad of traction in 0.1 minute increments. You then calculated the SRTs required from those tables, not making the mistake that causes problems in taking a SRT in isolation. Re-signalling projects used to come up with SPA reports (Signalling performance assessment, I think) which gave you a good head start for TPR construction.

Obviously real data is what you need, either by cab rides, stop watch times, going to the signalbox (bearing biscuits as normally signallers have an inbuilt dislike to train planners) or getting OTMR data.

TPS was meant to do a lot of things that it still doesn't, the I got dropped from its title fairly soon after as it certainly isn't integrating anything!

 

[Alfie1014]

As a pencil and paper guy I’d agree. The old timing offices used to have special sloping desks, rolls of graph paper, coloured pencils, a rubber and the obligatory cardigan. Drawing the graph by hand meant the brain assimilated the information as you went along, computed generated graphs are obviously much quicker but take a lot of studying to get your knowledge to the same level of detail.

Oh for one of those desks today! Plus of course the fug from your colleagues cigarette/pipe smoke! And what about the 'copy case' that needed to be checked when planning short notice (STP) timings to avoid conflicts? What I never understood was this just a ER(S) thing or something all planning offices used at the time?

 

[70014IronDuke]

... The related question is: if I know the horsepower and TE of the locomotive unit(s) and the gradient then I can clearly make a good stab at calculating the average speed of a particular train. Why, then, is it so hard to find HP values for the days of steam? Surely this information should be in every Ian Allan book beside the TE, boiler pressure etc.? Did the companies keep the values secret or something? TE will tell me if the train will go up a hill, but only HP will tell me how fast.

I've wondered for a long time about the lack of HP values from steam days and I've occasionally seen comments online to the effect that HP is not important or "just marketing". Yet it seems a vital statistic for drawing up timetables. What gives?

I don't want to pretend I'm an expert in this field, but I worked on a section at Derby back in the 70s which calculated the theoretical timings for various traction units. I did not work on those jobs personally, but was given an insight as to the history involved by my colleagues. Note that this section did not create the timetables - as I remember it, we just sent the theoretical timings to the planners, who then used these numbers, along with their practical knowledge of station dwell times, various recovery and engineering etc to draw up the timetable.

But to start at the beginning: I don't think you understand the complexities and number of variables encountered with steam traction, and are approaching this issue from the wrong way round.

Yes, the operations managers requested to the engineering department(s) that they wanted a locomotive to haul (say) 400 ton loads at an average speed of 55 mph. The civil side would say: no greater axle load of so and so, and of course, there was the maximum dimensions - restricted by the loading gauge. The mechanical designers would then work out what they could do on the design board, working with estimates of efficiencies and losses from past experience.

But it was a bit hit and miss. Ultimately, with steam, timetables were drawn up empirically - that is to say, the company ran locomotive class X with so many tons trailing load over section Y and found it took, on average, Z minutes and seconds. This may or may not have been up to the specification that operations managers had hoped to meet, but facts were facts. Many steam classes were designed with so much heating surface area, such and such a firebox area, with a maximum boiler pressure of N psi, with driving wheels and cylinders so big and so on, but they just didn't steam as well as was thought they would, at least not reliably so.

Or the driver/fireman needed to get used to how best to coax the best out of the different designs, under different conditions. Added to this mix, the calorific value of the coal varied. And the locomotive would gradually see thermal efficiency come down as the boiler tubes attracted scale between washouts.

BTW, I think you may have thought you read "TE is not important" (not HP). TE is important, but it is not the same as power. And yes, the SR in particular claimed the Lord Nelson was "the most powerful locomotive in the UK" based on it's theoretical TE. Which was rather Trump like of them, TBH. (But as it knocked the GWR off its high perch at the time, we can forgive them.)

In any case, without a static test bed, or static conditions (which you never really have in practice, unless on a nice, long, straight piece of track on a constant gradient) it is not that easy to calculate the actual power output of a steam locomotive very precisely.

But, then came diesel and electric traction, both of which have far fewer variables and foibles. You know, for example, the calorific value of the fuel to a very high degree of accuracy, and you are injecting specific amounts into each cylinder with far more precision than even the most conscientious fireman shovelling coal into fireboxes of various dimensions.

And you can test the motors and power units statically to know the potential power outputs very accurately. And along came computers.

At that point, sometime in the 60s, engineers did exactly what you surmise. As it was related to me, they did indeed feed into a computer the characteristics of a locomotive, the load and gradients. I think it was start to pass from Euston to Watford Jcn. And the actual timings came out to - honestly, I forget the number exactly - but it was something pretty spectacular like "within 6 seconds of what we achieved in practice, and then we knew we could do it."

They then set about feeding in all the lineside gradients as the basis to produce theoretical timings for all sorts of traction on the LMR, current and future, as requested. I assume similar efforts were made on the other regions. Apologies if I've got anything wrong here - but that's how I remember it.

 

[edwin_m]

I don't want to pretend I'm an expert in this field, but I worked on a section at Derby back in the 70s which calculated the theoretical timings for various traction units. I did not work on those jobs personally, but was given an insight as to the history involved by my colleagues. Note that this section did not create the timetables - as I remember it, we just sent the theoretical timings to the planners, who then used these numbers, along with their practical knowledge of station dwell times, various recovery and engineering etc to draw up the timetable.

I had a desk alongside what was probably the successor of the same team in the mid-90s. As I recall they had lots of leather-bound volumes of gradient profiles, and I think Tratim was the computer programme. It was privatised as part of AEA Technology, and like most things that company took over, they decided it was unprofitable and closed it down.

 

[DarloRich]

Timetable graphs are witchcraft.

 

[800002]

but the skill lies in being able to translate what's on paper to something that will work well on the ground, and to do that you need the knowledge and experience.

There are also plenty of examples of rules which don't appear in the TPRs, such as how to plan arrivals and departures at depots, which similarly gets passed down by experience.

Passenger depots are generally speaking planned by the TOCs. They do usually have arrival and departure intervals listed though. Freight too, but sometimes that gets a bit more complex. A great deal of information and knowhow is passed down though, I agree. They would be in a lot more trouble if it wasn't - just hope the tradition continues as it used to.

So although the processes might be far more computerised they still rely on good planners using the software to get a decent end result.

And the good planners a difficult to find! Especially for the non-standard stuff.

That's just cheating

Depends on your point of view
Necessary of you've got 'TRT rights' activated!

(bearing biscuits as normally signallers have an inbuilt dislike to train planners)

That's the first thing any planner is told, when they told they're going to visit the signal box! (is it any wonder why signallers have an inbuilt dislike for planners?!)

TPS was meant to do a lot of things that it still doesn't, the I got dropped from its title fairly soon after as it certainly isn't integrating anything!

I had heard that rumour... it did integrate a couple of things though, like BPLAN and Geography (but surely they were part of TrainPlan? -i never worked with TrainPlan).

 

[800002]

Timetable graphs are witchcraft.

Nah... just a fun thing to do!

 

[DarloRich]

Nah... just a fun thing to do!

i think your views and my views on fun differ!

 

[800002]

i think your views and my views on fun differ!

Indubitability .

 

[The Planner]

Passenger depots are generally speaking planned by the TOCs. They do usually have arrival and departure intervals listed though. Freight too, but sometimes that gets a bit more complex. A great deal of information and knowhow is passed down though, I agree. They would be in a lot more trouble if it wasn't - just hope the tradition continues as it used to.


And the good planners a difficult to find! Especially for the non-standard stuff.

90% of the good planners went in 2010, but that is another story....

I had heard that rumour... it did integrate a couple of things though, like BPLAN and Geography (but surely they were part of TrainPlan? -i never worked with TrainPlan).

B Plan was around prior to TPS and worked with Train Plan, and A Plan prior to that. Calling B Plan integrated with TPS is stretching it a bit.

 

[800002]

90% of the good planners went in 2010, but that is another story....

And the remaining 10% will likely be gone by the end of CP6.
(I could quite easily go on about good planners, but I shaln't).

B Plan was around prior to TPS and worked with Train Plan, and A Plan prior to that. Calling B Plan integrated with TPS is stretching it a bit.

I think i'll go with Plan C!

 

[Nagora]

BTW, I think you may have thought you read "TE is not important" (not HP). TE is important, but it is not the same as power.

I'm certainly aware of the difference and it's true that there are many, many posts on various forums where people patiently explain that there is no relationship between HP and TE so having TE alone isn't enough. However, I've seen plenty of people saying that HP isn't important or, rather, is not as important as people think and last week I saw someone on a board (I've mislaid the memory of which somewhere) more or less dismiss high HP numbers as marketing.

I don't think the line drawn, between the twospecific points equates to speed. It is the time taken to traverse the two points.

I see. I had assumed that both axes were to scale, so speed would translate directly to angle and vice-versa.

 

[800002]

I see. I had assumed that both axes were to scale, so speed would translate directly to angle and vice-versa

Yeah, sorry. It gets a bit tricky to try to draw it like that, as being frank - timetable graphs are 'drawn' based upon headways, between the mandatory timing points, so speed isn't really relevant (it's the time taken to traverse between two adjacent timing points).
Also, (thinking out loud here), as speed is never constant - so to speak - you couldn't have a straight line anyway, as the train speeds up from a start and slows to a stop, it would be an arch.

You can summise the average speed however, by dividing the distances between the points by the time taken to traverse the distance.

 

[Wilts Wanderer]

And the remaining 10% will likely be gone by the end of CP6.
(I could quite easily go on about good planners, but I shaln't).

There are still good planners about; it’s just those that are ‘centralised’ aren’t able to get out and see the real railway operating with all its regional eccentricities and local uniquenesses, and therefore can’t learn. The culture is increasingly about standardised rules and broad-brush planning techniques, set out in strategies written by managers who’ve never planned a timetable themselves.

That being said, those who aren’t ‘centralised’ still hold a lot of handed-down experience and know a thing or two about the traditional principles of planning a train service. The trick is not getting into arguments with the opposition!

 

[800002]

The culture is increasingly about standardised rules and broad-brush planning techniques, set out in strategies written by managers who’ve never planned a timetable themselves.

Sorry, yes - i was being a bit too generalistic there. Undoubtedly the BR 'old guard' will be all-but-gone though.
The managers are 'project managers' with the project coincidentally being the production of the Timetable.
The planners who show any sort of potential these days either try to become 'specialists' (most of whom nolonger plan trains) or move to an operator, or worse, just leave the planning department.
When they leave the juniors come in and it's almost back to square one.

That being said, those who aren’t ‘centralised’ still hold a lot of handed-down experience and know a thing or two about the traditional principles of planning a train service. The trick is not getting into arguments with the opposition!

Centralisation certainly had its pros and cons! I think MK does try to get folks out onto thier routes, but it's just so much more difficult and expensive (in time and money).

Depends who the 'oposition' is...

 

[70014IronDuke]

I'm certainly aware of the difference and it's true that there are many, many posts on various forums where people patiently explain that there is no relationship between HP and TE so having TE alone isn't enough. However, I've seen plenty of people saying that HP isn't important or, rather, is not as important as people think and last week I saw someone on a board (I've mislaid the memory of which somewhere) more or less dismiss high HP numbers as marketing. ..

Well, in the general context, they are wrong then. Without power, you ain't going nowhere fast.
Of course, under certain circumstance, such as severe line speed restrictions - such persons could be correct, at least to some extent. To take an extreme example, if GWR were to put HST sets onto the Heart of Wales line while boasting of "4,500 HP, 125 mph trains" - yes, while factually true, that would be absurd marketing spiel, because, of course, the units could not deploy this power in any meaningful way.
But in the normal meaning of things, more power translates into faster acceleration (for any given mass of train) and higher maximum trains speeds.

 

[70014IronDuke]

I had a desk alongside what was probably the successor of the same team in the mid-90s. As I recall they had lots of leather-bound volumes of gradient profiles, and I think Tratim was the computer programme. It was privatised as part of AEA Technology, and like most things that company took over, they decided it was unprofitable and closed it down.

Was this at what had been the Railway Technical Centre - Trent House or some such? The computer which worked all this stuff out was certainly up there in the mid-70s, but the section I worked on was in the LMR CM&EE Nelson Street. I would often take the input stuff up to the tech centre and stay for lunch in the canteen - but I can't remember where exactly I left it. Some reception, I suppose.
Tratim may have been the programme, but it doesn't ring a bell.

 

[The Planner]

It would be TRATIM as that is what the SRT calculation table books had plastered all over them, and as edwin mentions, it was AEA that did them.

 

[800002]

Well, in the general context, they are wrong then. Without power, you ain't going nowhere fast.
Of course, under certain circumstance, such as severe line speed restrictions - such persons could be correct, at least to some extent. To take an extreme example, if GWR were to put HST sets onto the Heart of Wales line while boasting of "4,500 HP, 125 mph trains" - yes, while factually true, that would be absurd marketing spiel, because, of course, the units could not deploy this power in any meaningful way.
But in the normal meaning of things, more power translates into faster acceleration (for any given mass of train) and higher maximum trains speeds.

Could a practice example include the redeployment of the diesel turbos from the Thames Valley (Paddington - Reading / Oxford) to Bristol - namely the Bristol TM - Severn Beach route.
My understanding is that the 16x turbos, despite being 'better' in terms of speed and engine power were 'outgunned' by the existing fleet. Their performance was woeful in the beginning.