Yes, hourly Perth-Inverness. Essentially two-hourly each from Glasgow and Edinburgh (slightly more services from Edinburgh iirc). A mixture of semi-fast and stopping services as well.Weren't there plans to introduce an hourly HML service each way eventually?
You can't normally allow trains from opposite directions to enter passing loops on a single line at the same time. They can only be brought up to the home signal. Once one has entered the loop, the second can be brought in as well. The reason for this is down to the safety overlaps required by the signalling system.Can any Scotrail drivers on here explain the operational limitations/ difficulties experienced on the highland main line on a daily basis.
I noted last year that at Cartridge, where 2 HST's were passing one another in the loop. It seems that one train has to be in the loop and stopped before the other one can approach. I suspect that leads to one or the other trains stopped somewhere waiting for that to happen. I'm not sure of that applies in both directions or not.
And I'm guessing the same applies to many of the other station /passing loops. Has the infrastructure upgrades/new signalling etc made a difference?
Clearly in the perfect world the HML would be double track throughout, but having mainly single track and a mixture of colour light / semaphore signalling creates havoc as soon as a train is running late. There seems to be very little ability to recover from delays.
The HST's seem to have better acceleration but worse braking than the 170's and also suffer from having to run at lower non SP speed limits.
There appear to be lots of reasonably straight /lightly curved sections of track that could allow faster speed limits, but the current line speed profile seems to have been set on the acceleration capabilities (particularly uphill) of the wheezy 170's and longer 2+8/ 2+9 HST's. There was clearly no point posting an 85mph/90mph limit on the uphill section from Dalwhinnie towards Drumochter, because neither of the legacy traction would achieve it up such steep grades. Whereas the sprightly 2+4 HST's can achieve it much more easily!
Shorter blocks would make it a lot easier to "flight" trains, allowing capacity increases and/or easier recovery using the passing loops that already exist. But it wouldn't be a cheap undertaking.Clearly in the perfect world the HML would be double track throughout, but having mainly single track and a mixture of colour light / semaphore signalling creates havoc as soon as a train is running late. There seems to be very little ability to recover from delays.
I'm not a Scotrail driver but I'm a Scotrail passenger living on the Highland Main Line and your post here describes very well how frustrating the route is. Pre Covid I spent a lot of my time stuck on trains in places like Stanley or Dunkeld just waiting for something travelling in the opposite direction to show up late.Can any Scotrail drivers on here explain the operational limitations/ difficulties experienced on the highland main line on a daily basis.
I noted last year that at Cartridge, where 2 HST's were passing one another in the loop. It seems that one train has to be in the loop and stopped before the other one can approach. I suspect that leads to one or the other trains stopped somewhere waiting for that to happen. I'm not sure of that applies in both directions or not.
And I'm guessing the same applies to many of the other station /passing loops. Has the infrastructure upgrades/new signalling etc made a difference?
Clearly in the perfect world the HML would be double track throughout, but having mainly single track and a mixture of colour light / semaphore signalling creates havoc as soon as a train is running late. There seems to be very little ability to recover from delays.
The HST's seem to have better acceleration but worse braking than the 170's and also suffer from having to run at lower non SP speed limits.
There appear to be lots of reasonably straight /lightly curved sections of track that could allow faster speed limits, but the current line speed profile seems to have been set on the acceleration capabilities (particularly uphill) of the wheezy 170's and longer 2+8/ 2+9 HST's. There was clearly no point posting an 85mph/90mph limit on the uphill section from Dalwhinnie towards Drumochter, because neither of the legacy traction would achieve it up such steep grades. Whereas the sprightly 2+4 HST's can achieve it much more easily!
Looking at it from an operational view - to run an hourly service - and assuming you could average 60mph, then your trains are going to cross each other every 30 mins or so. If the trains can be booked to leave and arrive at Inverness or Perth at around the same time - then the trains can pass each other at the main station stops half an hour apart.Shorter blocks would make it a lot easier to "flight" trains, allowing capacity increases and/or easier recovery using the passing loops that already exist. But it wouldn't be a cheap undertaking.
Remember also that due to the availability of paths out of Waverley and, in particular, Queen Street, these trains can only depart from, or arrive into, Central Scotland at particular times each hour. It may not be possible to have the timetable you describe. I still think that at least one long dynamic loop would improve reliability.Looking at it from an operational view - to run an hourly service - and assuming you could average 60mph, then your trains are going to cross each other every 30 mins or so. If the trains can be booked to leave and arrive at Inverness or Perth at around the same time - then the trains can pass each other at the main station stops half an hour apart.
The half hour sections seem to be Inverness to to Aviemore, Aviemore to Dalwhinnie, Dalwhinnie to Pitlochry , and then Pitlochry to Perth.
Your Northbound service and Southbound services ideally need to pass each other at Aviemore and Pitlochry at station stops. Timed correctly - your southbound service joins the double track at Dalwhinnie a few minuites before the northbound is set to hit the single track. Similarly, the southbound service can hit the double track at Stanley around 5 to 8 mins before the Northbound service.
If double tracking cannot be achieved throughout - would it be better to extend some of the loops into shortish double track lengths be a better idea?
I wonder if re-instating the HST differentials installed in 1984 and removed around 1993 would be worthwhile. They were removed because it was decided they were of limited benefit - only the 'Chieftain' could use them and didn't significantly improve journey times but the shorter ScotRail sets can accelerate much quicker so they may be of more beme fit in producing a higher average speed as you suggestLooking at it from an operational view - to run an hourly service - and assuming you could average 60mph, then your trains are going to cross each other every 30 mins or so. If the trains can be booked to leave and arrive at Inverness or Perth at around the same time - then the trains can pass each other at the main station stops half an hour apart.
The half hour sections seem to be Inverness to to Aviemore, Aviemore to Dalwhinnie, Dalwhinnie to Pitlochry , and then Pitlochry to Perth.
Your Northbound service and Southbound services ideally need to pass each other at Aviemore and Pitlochry at station stops. Timed correctly - your southbound service joins the double track at Dalwhinnie a few minuites before the northbound is set to hit the single track. Similarly, the southbound service can hit the double track at Stanley around 5 to 8 mins before the Northbound service.
If double tracking cannot be achieved throughout - would it be better to extend some of the loops into shortish double track lengths be a better idea?
I was informed by two retired BR ScotRail engineers that BR ScotRail installed several HST differentials in the early 1980s. Among the first was on Edinburgh-Aberdeen in 1982 iirc, Perth-Inverness was partially done in 1984 for the 'Chieftain' launch with further sections added in 1985 for an accelerated schedule.Hmm. I will have to check for the HST differentiala in our distance chart archive.
Yes, paths in and out of Waverley and Queen Street are an issue, but the other major factor in HML flexibility is the continuous 15 mile single section between Ladybank and Hilton Jn. If anything I would improve capacity there before I did anything with Perth-Inverness itself, it's already trying to support an hourly service.Remember also that due to the availability of paths out of Waverley and, in particular, Queen Street, these trains can only depart from, or arrive into, Central Scotland at particular times each hour. It may not be possible to have the timetable you describe. I still think that at least one long dynamic loop would improve reliability.