Large and Small locomotive economics, ex-West Somerset Railway developments

87's a great steamer and most people's favourite Garratt (mine's 143) and you can overfire them at times, particularly on the northern end of the line.

 

Firemen are all saints or very nearly saints and as such close to perfect . It is true though that drivers do vary a lot in temperament.

 

No comment!

What is true is that getting a loco to get from one end of the line to the other in a safe and efficient manner is very much a team effort, and a driver can influence how a trip goes from the fireman's point of view according to how they drive. In particular on an engine working close to its limit, if the pressure starts to fall, sometimes the best thing to do is to back off and save steam; and sometimes the best thing to do is to work the engine harder and increase draught on the fire and increase steaming rate. Whether the driver makes the right choice in any particular circumstance only becomes apparent in retrospect!

Tom

 

Quite right Linda on 8 cars is quite an intense firing turn for a preserved railway. It needs to be kept right on the red for 13 miles to get the best out of it. The feed only goes off to throw 3 shovels in as fast as you can every couple of minutes before getting it straight back on. Drop five pounds below the red line and it is a struggle to keep the water going in. On top of that the whole thing is wobbles about like crazy at 20mph, with rods flailing around at high speed in front of your face and a great noise from the front. Throw in a tight timetable with tricky rail conditions in the woods and it becomes a real challenge. Amazing fun though. These Std gauge folks don't know what they're missing.

Tim

 

Excellent stuff, Tom! I was living that.

Regards,

John

 

Thanks for that, Tom. You've really brought it to life, on a small loco it's all about small little inputs in terms of both firing and the injectors. But knowing your love of small and old locos you relish the challenge of it!

 

Glad you liked it - they don't all go like that, that trip worked particularly well!

Tom

 

Back in October, in the space of about a week or so I had an S15 on 420 tons (the day Braunton came to visit - we had 7 passenger coaches + the Braunton support coach + Braunton with the regulator shut to save water) and each P on 64 tons. The variety definitely makes for an interesting hobby, though if someone said to me "from now on in your career, you will only ever work on one loco, but you can choose which one", I'd pick 178 ...

Tom

 

Spurred on by both JTX & Tom, here's a day in my life on the NYMR, well some of it, anyway. It's based on my recollections of what actually happened on a day in October last. It's a bit longer than the previous takes but the NYMR is a longer line!

It’s 6.30 in the morning and still dark as I walk up towards the sheds at Grosmont. I’ve been treading this path for over thirty years now and yet each time is still an adventure. The first thing I do after walking through the shed door is to sign in followed by a careful look at the various notice boards; then it is on to look at the loco roster board. Locos are generally rostered the evening before so I’ve no definite idea of which loco I will get but, as I’m rostered on a Whitby turn, the choice is going to be fairly limited. Today, I see that it is Black 5, No.45428, a long- time favourite of mine from my youth, much of it mis-spent at Holbeck. Finding the loco on the front of No.4 road, my fireman –we’ll call him Rob but that’s not his real name - is already there and is shoveling a few rounds of coal on as I climb into the cab and store my bag. We exchange good morning and some jovial banter whilst I have a quick look at the water and pressure gauges and a general glance around the cab. All seems well.

We’ve also got a Cleaner with us today; a 17 year old called Pete (although again, that’s not his real name). Actually he’s now referred to as a Trainee on an Improvement turn but old habits die hard and he is still frequently referred to as a Cleaner or third man. Rob has set Pete on doing various preparation tasks, such as filling and trimming the lamps and filling the sandboxes whilst he busies himself in cleaning the cab. Outside, three other people are busy cleaning the loco and I note that they have put a ‘Not to be Moved’ board on the front left lamp bracket. Cleaners, I’ve noticed, tend to flock together; there are either lots of them or none!

I busy myself with oiling up. This is done systematically so that nothing is missed. Black 5’s are fairly easy to oil up, although not as quick and easy as a Standard, and before long I have gone right round the loco at ground level. There are still oilpots on the running plate to fill, though, and I get a ladder to help me with this. I could do it from the running plate but I have learned that it is easier with a ladder. I curse Mr Stanier for positioning some oil pots behind the injector delivery pipes which require you to hold them open with one hand whilst holding the pourer in the other, all the time avoiding burning yourself on the pipe and falling off the ladder/running plate! Why these have never been moved, I don’t know. Whilst up high, I fill the two mechanical lubricators.

It’s now time to move onto the pit so I ask the cleaners to remove their board and unplug the power supply that has been charging the batteries for the electrical equipment. Once on the pit, I go round the axleboxes, checking the oil level and filling, as necessary. That done, it’s time for the examining fitter to come long and give it a once-over. It was examined last night so he doesn’t expect to find anything but the rules for steam locos on the big railway require a fresh examination. The AWS, TPWS & GSMR are all checked; fortunately we don’t have OTMR, as well!

Once all is done and everything checked and tested, the boiler is blown down, removing something like half a glass of water in doing so. Final task as we leave the pit is to fill the tender with coal from the coal hopper. The loco is going to do 108 miles today so it is given a fairly ample supply. We then drop down to the water column to top up the tender tank. Rob also checks the security of the coal to make sure no lumps will fall off. We then wash off before ringing the signalman to let him know we’re ready.

Once we get the signal, it is off through the tunnel and into platform 3, where we briefly stop to pick up a radio and a set of keys from the signalman. Our first train is Whitby bound and our stock is in platform 2 so it is into siding 2 to await the signal to let us back into the platform. When we get the signal, I open the regulator and the view forwards disappears in a cloud of steam from the drain cocks. We start to move forward into the thick mist, all the time knowing that there is a set of coaches somewhere in front. Fortunately, I’ve remembered to check where the coaches were as we ran past them so I’ve a reasonable idea of how far we can safely go. I get the loco going so that I can shut the regulator and coast towards the stock. Eventually, we come out of the cloud and the coaches are still a good way away. The guard comes on the radio to say we can come onto the stock so I give 45428 another quick burst of steam whilst trying not to disappear into the mist again. We gently buffer onto the stock and the steam brake comes hard on before there’s a chance to bounce off.

Whilst Rob is busy coupling up, I send Pete for some tea and our ‘packing up’. Once coupled and steam heat on, it’s time to do a brake test. Pete returns with the teas but no lunch. We can pick it up when we get back, he says. I explain unwritten rule No.1 ‘Never be separated from your food’ and send him back again.

It’s now getting nearer to our departure time; Rob is busy making up his fire. It’s downhill to Whitby but only just and there are lots of curves so he will need a reasonable fire. Pete returns with our food. Unfortunately, we aren’t allowed to take Cleaners onto Network Rail so I arrange for Pete to meet us when we get back and tell him that he will be firing to Pickering.

The guard comes up and confirms a satisfactory brake test and gives me a slip of paper with our train details on it. I note that we have 7 coaches and that the maximum speed is 30 mph, which is line speed from Grosmont to Whitby. We must have a full complement of TTI’s on board, otherwise we would be limited to 25mph. I enter the train reporting no. into the GSMR and then It’s time to get the single line token for the run to Whitby. I go to the cabinet and phone the Nunthorpe Signaller. There follows a well-rehearsed and generally routine conversation.

‘Nunthorpe Signaller Speaking.’

‘Nunthorpe Signaller, this is the driver of one tango one zero at Grosmont Intermediate Token Instrument requesting permission to withdraw a Glaisdale to Whitby token for the purposes of travelling to Whitby.’

‘Driver one tango one zero you can withdraw the Glaisdale to Whitby token.’

‘I have withdrawn the token; can I now have permission to pass the down stop board and proceed to Whitby?’

‘Yes, driver one tango one zero, you have permission to pass the down stop board and proceed to Whitby.’

‘You have given me permission to pass the down stop board and proceed to Whitby.’

‘That is correct.’

I give the token to Matt, who is to operate the ground frame and confirm with him that we have authority to pass the stop board and proceed to Whitby. He then goes and sets the road onto Network Rail whilst I go back to the loco, remembering to turn on the high intensity headlamp on the way. After a couple of minutes, the signal comes off. Technically, it’s not a signal so much as a point indicator as it is controlled by switches on the points and not by a lever on the ground frame. The guard gives the right away and we are off.

A blast on the whistle, brake off and regulator open. Away we go, limited to 10 mph over the crossover. Once over the crossover, we have to stop to let Matt reset the ground frame and bring the token to me. To minimize the distance we go beyond the points, I have a stopping point for different lengths of train. With 7 coaches it is with the first coach fully on the bridge. After a couple of minutes, Matt arrives and climbs aboard the loco. He hands me the token and says, right away for Whitby.

I start off in full gear back but, as soon as we start away, I shut the drain cocks and start to slowly wind the reverser back. Speed is soon up to 30 mph at which point I shut the regulator. We haven’t gone more than a few yards at this speed when it is time to make a good brake application. Bridge 46 has a 10mph speed restriction for ‘heavy’ locos and our Black 5 fits that category. If it had been 75029 or 76079, the restriction wouldn’t apply. As soon as the loco is over the bridge, (it’s only the loco that is restricted) the regulator is opened again and the reverser dropped to about 45%. However, we are now into a series of four reverse curves and the track is not the best so I keep the speed down to 20 mph. The tender gives a couple of heavy lurches, closely followed by the loco. I wait till the whole train has passed this spot then I open the regulator a bit more to get up to line speed and wind the reverser back to about 20%. Not for long, though, as there is another set of reverse curves with a 25 mph restriction and I need to touch the brake to comply. Although it is downhill, I then need to keep steam on around these curves as, otherwise, speed would drop significantly.

Once off these curves, we are back up to line speed but on a length of straight, welded, track and the difference in noise is immediately noticeable. The regulator is only just cracked and the reverser at 20% and this is ample to keep us going at line speed. Running in reverse, my view ahead is rather restricted and I’m stood with my head out of the window although every minute or so, I have a quick sweeping glance around the cab to check the gauges and make sure all is well. All too soon, the AWS horn sounds to warn of the fixed distant for Sleights. There is a Stop board at Sleights and all trains have to stop there. Once we have come to a stop, I pick up the GSMR handset and press the button to dial the signaller. I tell him that we have arrived at Sleights, complete with tail lamp and request permission to pass the stop board. Once this is given (and repeated back) I look back for the guards right away and off we go. Bridge 53 is another 10 mph bridge so it is a slow departure from Sleights. However, once the loco is clear, we are quickly back up to line speed, whistling for the series of user worked level crossings. Soon the AWS horn goes again to remind us that we are approaching Ruswarp level crossing with its 20 mph limit. Rob, who has been steadily shoveling to keep the pressure and water up, is now on the lookout for the flashing white light that tells us that the crossing has operated correctly.

We are non-stop through Ruswarp and soon up to 25 mph. Although the linespeed here is 30 mph, the curves as we approach Larpool viaduct are quite sharp and we keep to 20-25 mph round them. If you’ve ridden on the loco, you’ll know why! All too soon, the AWS horn is going again and we are stopping for the points indicator by Bog Hall crossing. I give Matt the token and he gets down and starts the long walk to the ground frame.

The points indicator, which has been showing a yellow aspect with a ‘1’, changes to red and then, eventually, goes back to yellow with a ‘2’ indicated. A check to make sure the crossing is clear, a blast on the whistle and we are off on the last few yards into Whitby Town station. As we run into the new platform 2 I quickly glance at the speedo to make sure that we are doing less than 10mph or the TPWS will stop us. However, the curve is bringing the speed down quite quickly and I have to give the loco a breath of steam to keep the train moving. It is half term week and there is a good number of passengers awaiting our arrival.

As soon as we arrive at Whitby, Rob is down ready for me to ease up so he can uncouple whilst I do the lamps. He then goes to the run-round ground frame, which Matt will have given the release to. Rob calls me back which I do slowly. Once we are clear of the point blades, there is about 15 feet to spare between the loco buffers and the friction arrestor buffer stop. If we touch the buffers, it has to be reported and the buffer stop has to be examined daily by the station staff as a check. Rob operates the ground frame and calls me forward into the loop and I stop once clear so he can re-set the frame before joining me on the footplate. We run up the loop to the stop board and await Matt calling us forward into the stub of Bog Hall sidings before re-setting the road to take us back into platform 2. The guard waves us onto the train and we quickly couple up and perform a brake test.

About five minutes before departure (not too early or the signaler won’t let me) I phone and get permission to withdraw a token which I hand to Matt who then goes and sets the road out of platform 2. The points indicator goes from red to yellow and I look back for the guards right away, relayed to me by the station staff as the platform is on a curve. We’ve just got nicely into our stride when we have to stop once more for Matt to reset the ground frame and bring me the token. It’s made a longer walk because we are not allowed to stop on Bog Hall crossing. The return journey to Grosmont is similar to the run to Whitby although, in this direction, we have to stop for the level crossing at Ruswarp and run straight through Sleights, albeit at 10 mph. I can also sit down, rather than stand! As it is uphill all the way combined with the curves, Rob is shovelling most of the way to keep the water and pressure at a satisfactory level. The pull out of Sleights is quite hard and the train takes a while to get up to line speed. As we approach Grosmont, Rob starts to build up the back end ready for the climb to Goathland. We stop at the ground frame to let Matt off. He gets in touch with the Grosmont signalman and seeks permission for us to enter the station. We are due to cross a train here and, as ever, two trains cannot enter the station at once. Once Matt has the necessary permission he sets the road for platform 3. The points indicator will go to yellow and a large ‘3’ is illuminated. We then get the right away from Matt and I whistle and open the regulator. As often happens here, we don’t move and I have to wind it into back gear and allow the train to roll back a few feet before winding it back into full forward and trying again. Making sure that you don’t slip is quite difficult as you shouldn’t use sand on the pointwork. With seven coaches, I need to get right up to the starter signal to get as much of the train on the platform as possible.

Pete is there on platform 3 and he has three cups of tea for us all. Well done! I tell Rob that he can drive and, as previously agreed, Pete will fire. Although I have been out with Rob many times, this is the first time I have met Pete so I need to keep a good eye on him. Boiler pressure is about 215 and we have ¾ glass of water. Pete looks at the fire he has been left and starts to put some coal down each side, keeping a watchful eye on the smoke. The down train runs into the station so departure is imminent. Pete is busy with the injector and the shovel, keeping the pressure at about 215 psi. Shortly the crossing gates are opening for us and Rob winds the reverser into fore gear. We have a full glass of water and still have 215 psi. The starter comes off and I am looking back for the guard. I’m also concerned that we haven’t got the token but the signalman comes down his steps with it in his hand. We get the right away and Rob whistles and opens the regulator. We move forward but 45428 decides that it would like to slip. Oh dear. Rob shuts the regulator and opens it more carefully. Getting out of platform 3 is more of a challenge than departing from platform 2 as there is a bit of a dip in the track. It is a fight for Rob and the start is slow but, eventually we are going over the crossover and onto the running line. Pete is keeping an eye on the pressure and those slips have drawn the fire so he puts the injector on once more. As we enter the tunnel 45428 is getting into its stride and Rob is winding the reverser back. We round the curve by the shed and I walk across to the fireman’s side to observe the section signal. Pete is also watching for it and calls it ‘clear’ as soon as it comes into view. I’m watching Pete with interest. He is stood there, watching the pressure gauge and making no attempt to fire. Most cleaners and some firemen would be shoveling by now. The pressure is near the red line and the injector goes back on. As we reach Esk Valley and the start of the 1 in 49, Rob opens the regulator fully and the reverser is at 50%. Pete puts a round of eight on and puts the shovel down. That’s unusual for a cleaner as most tend to hang on to it. 45428 is now well into its stride at a steady 17 mph and Rob winds the reverser forward slightly as we go round Green end curves and under the bridge. Pete puts another round of eight on and again puts the shovel down. The boiler pressure is little short of the red line and he is keeping it there by balancing the dampers and firehole doors with the injector singing away. This routine of a round of about eight shovelfuls every couple of minutes continues. I am getting quite impressed by Pete. His firing is economical and routine. I know from experience that Rob would have been firing almost continuously and there would have been continuous smoke at the chimney. I’ve hardly seen any of the latter with Pete.

In the driver’s seat, Rob is keeping the speed at a steady 16 mph, marginally faster than the 15 mph TSR we have at this point. He is winding the reverser back and forth by small amounts as we go into and out of the curves. At Beckhole bridge the TSR ends and Rob winds the reverser forward slightly more to get the speed up a bit. But not too much; 20 mph is getting near the sensible limit with seven on. There’s a flange lubricator just beyond Beckhole and it causes a momentary slip which catches Rob unawares although by the time he’s reacted the slip is all but over.

Pete puts another round on and then starts to tidy up, using the slacker pipe to swill down the footplate. He appears to have decided that there is enough to get us to Goathland but I think he is a bit premature. However, as we have a full glass of water and full boiler pressure, I decide to say nothing and wait and see. In a minute, we’re crossing Bridge 30 and into the curve at Darnholme. The gradient here steepens to 1 in 42 for 15 chains and there’s a noticeable slowing of the exhaust beat. Rob winds the reverser forward a bit more to 55% to compensate. The pressure has fallen slightly so Pete knocks the injector off to compensate. As we come up the final bit towards Goathland, the water has come into sight so Pete puts the injector back on. The pressure starts to fall quite noticeably at the home signal comes into view. However, it is ‘off’ so this part of the battle is almost done. Rob slams the fully open regulator shut and immediately re-opens it on the first valve. With seven on, he keeps the regulator open until the loco reaches the footbridge, half way down the platform. Even though the majority of the train is now off the 1 in 49, the gradient in the station is quite severe and the train slows down quite quickly. There are markers on the sleeper ends to indicate where to stop so Rob is aiming for the ‘7’ mark. It needs a little bit more steam to get it there, though, Rob dropping the vacuum brake at the last moment to prevent the coaches see-sawing. Pete exchanges the token with the signaler for the train staff for the next section as we are not due to cross a train here. Once stationary, we can observe that there is about 1½” of water showing in the glass; quite a change from the full glass we had just before entering the station. With a Black 5, anything less than about ¾ glass as you come into Goathland isn’t enough. The consequences of Pete ceasing firing too soon are shown on the pressure gauge, which has now dropped to 175 psi. I suggest to Pete that he stopped firing too early and he agrees. A lesson learned. We have a five minute wait here and Pete busies himself in sorting out his fire. The injector is still on and, at departure time we still only have 175 psi. Rob asks if we should wait a bit longer but I say that we’ll be OK and let’s go. Rob looks back and the guard is ready so waves his flag. (Unwritten rule no.4: ‘Don’t look back until you’re ready to go’) The signal’s off so away we go.

Pete has got his fire back into shape and, once we get the blast of the exhaust drawing the fire the pressure slowly starts to rise against the injector. Rob has got us up to 25 mph and immediately after he shuts the regulator for a short 15 mph slack (for a ground slip.) The train slows naturally on the grade and once the speed has dropped to 15, Rob opens the regulator again to keep it at this speed. It’s not long before we’re off the slack and he can give it its head again to get it up to line speed. Pete is busy with putting another round on and normality has returned with the water near the top of the glass and 210 psi on the clock. Time for another round before summit and Pete then slacks round again and tidies up.

All too soon we are at and over summit so it is largely downhill now for the next twelve miles. Rob shuts the regulator and we coast along quite merrily at line speed but as we approach Hallelujah bridge speed starts to slow so a bit more steam is needed to keep up the momentum. Why Hallelujah? Well when you’re on a down train and having a bad trip, this bridge signifies the end of the hard climbing and crews can say ‘Hallelujah, we’ve made it!’

Once over Hallelujah bridge the train starts to run away from you so it is a question of Rob keeping it in check with the brake. Dropping the vacuum to 15” does the trick until we get onto Northdale straight at the end of which we have to slow further for the 15 mph restriction on Newtondale curves. Pete is now looking out for a green flag from the guard signifying that there are no passengers to set down at Newtondale halt. The guard duly obliges and Pete shouts across ‘Green from the Guard’ and acknowledges with a brief blast on the whistle

Once round Newtondale curves Rob briefly opens up to get back to line speed but is wary that we might have to stop if there are passenger waiting at the Halt. It’s all clear today and we run through at line speed. Shortly we pass the site of Newtondale ‘box and the line drops away quite noticeably as we run onto the 1 in 49 gradient. More braking by Rob to keep the speed in check. In fact, braking to keep the speed in check is the order of the day until we approach Levisham outer home, which is invariably at danger. Rob drops the vacuum a bit more and, as the speed drops to walking pace, the signal inevitably comes off. We crawl round the right hand curve, Pete looking out for the Inner home, which again is at danger but is also pulled off as we approach. We are due to pass a train here but there is no sign of it as we run into the station and I give up the token to the signalmen. Rob brings the train to a halt, aided by a ‘7’ painted on a sleeper end. With only three coaches possible on the platform, it is an embarrassment if you both stop too early or too late. Too early and you lock the track circuits and too late means most of your train is off the platform, perhaps including the guards van.

I get down and walk back to the box to be ready to pick up the next token, noting that the down train is visible on Levisham straight so will be in imminently. This train comes to a halt at the same time I get to the box and the driver exchanges tokens with the signalman. A matter of a few seconds and he is on his way again but I have to wait a couple of minutes whilst the signalman goes through his routine. LIFO (last in, first out) generally applies when trains cross.

Once back at the loco, I look back for the guard and we are right away again. Whilst I’ve been away, Pete has been attending to his fire, ready for the start. It doesn’t take long for Rob to get up to line speed and once there he shuts the regulator and puts the reverser at 40%. Nothing else is now needed until we approach Kingthorpe curves three miles further on. It’s 15 mph round these curves so Rob drops the vacuum to 15” to bring the speed down. Once at 15 mph, he brings the reverser back to 25% and opens the regulator slightly to keep the train moving at this speed and, once off the curves, a bit more to get back to line speed. Not for long, though, as there’s presently a 15 mph restriction over Hunting Bridge crossing due to the flood prevention works being carried out. The crossing is manned and we get an all clear from the crossing keeper so, once over, it is back up to line speed. The NB 21 signal Banner repeater is showing ‘off’ but Pete is still looking out for the actual signal and shouts ‘clear’ as soon as it comes into view.

We’re nearly at Pickering now and Pete is starting to build up his fire a bit to be ready for the return trip. Only, the back end, though, none down the front as he doesn’t want to make steam or smoke. Off, too goes the steam heating to give time for things to cool down. As we round the curve approaching New Bridge, No.20 signal is showing clear but Rob brakes to bring the speed down to 10 mph for the token exchange, which Pete carries out. The pouch picked up contains a message for me, authorizing me to pass the stop board at Pickering platform 1.

The approach to Pickering is slow with over half a mile of 10 mph running and a 5 mph over Trout Farm crossing but we are soon approaching No.18 signal, which is showing red. This is expected, as it is approach controlled and, if we are going slowly enough, will change to yellow before we reach it. A flashing white light for the crossing and Rob whistles a warning. Once over the crossing Rob opens the regulator a bit to get us round the reverse curves entering the station and brings the train to a gentle stop with the loco’s chimney just outside the station roof. (It’s frowned up on to contribute to the dirt on the roof!) Journey’s end and time for me to get some more teas whilst Pete uncouples under Robs supervision.

30 miles under our belt with another 42 to do but that’s enough for now!

 

Thanks Steve. It's interesting just how much "driving" goes on! Also how much extra procedural complexity is introduced by running on the mainline.

But the burning question: what are unwritten rules 2 & 3?

Tom

 

You are right,; there is a huge amount of procedural complexity involved in running those extra six miles into Whitby. I specifically included the exchange of words with the Numthorpe signaller and the reference to station staff having to inspect the buffer stop to see if we've touched it. And this is on what is really a basic railway.

Unwritten Rule No.2 is quite simple: ' Never go near the railway in clothes that you are not prepared to throw away at the end of the day.'
Unwritten Rule No.3 is probably the most important: 'Never expect to do what you expect to do.'
All unwritten rules are, like most rules, brought about by bitter experience. I'm sure that you have your own.

 

Ah yes. No. 1: Never go to the railway without footplate clothes - you never know when you will be drafted onto the footplate at the last moment. No.2 : Never assume you have plenty of time to prepare (so fire alight then tea, not the other way round!). No. 3: never indicate a likely time you will be home to your wife unless you are actually in the car with the engine running. But most importantly No. 4: Don't assume Swindon knew what they were doing!

Tom

 

Swindon knew what they were doing, all right; making life as difficult as possible for footplate crews and maintenance fitters.

 

GWR men were just made of sterner stuff than those Southern softies

 

Fascinating stuff chaps! Steve-you mentioned that two trains wouldn't be allowed to enter the station at the same time-I'm racking my brains for the reason but coming up blank... Is it so the signalman can observe both trains?

 

I imagine it would be to do with whether there are traps at the end of each loop.

Imagine a simple passing station with a loop on a single line, with starting signals at the end of each platform but no trap points. (Examples would include Kingscote, Corfe Castle etc). Now imagine trains are simultaneously approaching from each end, with the intention of passing through the loops. The starting signals on each platform are, correctly, showing red. So far, so good, but if one train failed to stop at the signal, there would be no protection against it proceeding onto the points where the loops rejoin, potentially causing a collision with the train coming the other way. So to prevent that, a train in one direction (doesn't really matter which), will be held until the other one has safely arrived and stopped.

That explains, incidentally, why a typical timetable at a crossing station will have one train that had minimal time for station work, but the other often has eight or ten minutes. Effectively the timetable will be arranged so that train A arrives and gives up the token. Signalman goes back to box and puts the token through the machine, then clears the signals for train B, which arrives, exchanges tokens, does platform work and departs. Finally the signalman does his work and clears the signals for train A. Hence the "first in, last out", with train B having spent maybe only a minute or two at the station, but train A having waited for probably at least six or eight minutes. If you think it out from the signalman's point of view, assuming the signal box is situated at one end of the station, then the signalman does the least walking if the timetable is arranged such that the train that arrives from the non-signalbox end arrives first.

Tom

 

Great Tom-makes sense! Thanks

 

Tom has essentially explained the reasons as I understand it. I'm not sure whether it also applies where there are trap points as well. We need a qualified signaller to tell us that.
Tom has also explained very well why FILO generally applies.

 

Double post. Deleted.

 

My guess it that it has more to do with sufficient overlaps beyond the starting signals rather than trap points. If the starting signal is placed very close the loop exit then there may not be enough room in the overlap of the signal to assume that a train that passed the signal at danger would be able to stop before it reached the single line. If the signal was far enough back from the single line then it might be permissible to allow a train to approach that signal while also allowing another train to pass along the single line into the other part of the loop.

Interestingly, the WHR allows two trains into a loop at the same time because it has been defined that there is enough of an overlap beyond the stop boards to allow this to happen safely, while on the FR (except at Tan-y-grisau (I think) which has WHR style signalling) only one train is allowed into a station at one time.

I have had a look at the RSSB rule book for the signalling regulations for single lines such as how most preserved railways are signalled and the rule books don't contain any instructions for the crossing of trains, they used to but must have been taken out in the recent revision of the books. I suspect that it's now instructions at local level that define how trains are to be signalled although the introduction of TPWS will have opened up a degree of flexibility at some locations. I would assume that some places on the Aberdeen - Inverness line where it's single line with passing places (and indeed tokens for some sections) will have some similarity with how preserved lines operate.