Is it realistic that you can contact the dispatch in the Spirit of Steam route without walking to a trackside telephone or telegraph? Obviously analog radio had already existed by then and aircraft used it, but it doesn't seem like the Jubilee or the 8F have antennas(most radio broadcast back then would be AM). But surely something existed before GSM-R, I don't think diesel drivers were in the dark in the 1970s either.
GSMR was preceded by Cab Secure Radio (CSR) which was first introduced (initially only in the Glasgow area) in 1986. Prior to that it was not possible for the Driver to contact the Signaller directly from the cab. They would need to walk to a Signal Post Telephone (SPT) or lineside telephone.
There was also NRN radio which was the first cab to shore radio along with the bespoke system for RETB signalling in the north and west of Scotland. However in the steam era and early diesel there was no in cab means of contacting the signaller. The driver had to alight and use telephones at signal posts or in certain locations with long block sections additional lineside telephones were provided at intervals. I read an account of a train failure on the West Highland line in the 70’s, mid section, where the secondman had to walk five or six miles to the nearest block post to summon an assisting engine.
I think of CSR as being part of NRN - i.e. NRN was the wider radio network linking locations across the railway network, and CSR was the element of it which was used in the cab. I may be getting confused though. All these terms bring back a lot of memories, but it’s amazing how quickly the new terms and acronyms take over the same head space, and what was once second-nature becomes cloudy!
The anomaly with NRN was that emergency calls actually came through to the Zonal Control office rather than the controlling signaller. Which meant we had to turn the call around to put out an all trains stop broadcast to trains in the area, then tell the signaller. If a signaller wanted a train stopped they had to get Control on the emergency hotline and we would do the emergency broadcast. Drivers could also dial railway internal numbers on a normal connection from the NRN but there was no way for external contact with individual driving cabs. All that changed with GSM-R with train to shore comms going to the signaller though emergency calls were slaved to the Control, listen in only, preceded by a klaxon akin to Star Trek Red Alert. Guaranteed to get the adrenaline going and if your area, the sinking feeling the train service was going into doodoo for the next 3 hours.
Why wasn't VHF radio used before GSM-R? After all, with a trackside telephone only the driver can contact the dispatch, not the dispatch to the driver. As for why dispatch would need to contact the driver, there are even scenarios in TSW about it, where trees fall on tracks, cows stray onto the line, you help a broken down locomotive etc.
It’s about balance of cost versus benefit. Drivers were instructed that if detained at a red signal for 2 minutes, they must use the Signal Post Telephone to contact the Signaller (this is still the instruction, but now you’d use GSMR). So it was always possible to contact the Driver - either via station staff at the next booked stop, or otherwise hold the train at a red signal and wait for the Driver to contact the Signaller. Clearly a radio system is better, allowing the Driver to be contacted more quickly. However, setting up a radio system with good coverage over the entirety of the UK rail network was a vast and highly expensive undertaking. Over time, technology developed to make installation of such a system gradually cheaper (and the resulting system more reliable), and at the same time as a society we became gradually more risk-averse. Eventually the lines crossed, and the expense came to be seen as justifiable for the benefit, so the system was designed and installed - albeit in stages over a long period of time.
How did they know where the train was without GPS? Other than estimating from its last departure time and average speed limits on the route(which isn't a very accurate method especially if you do the math in your head). Other than being quicker to contact, radio also has the benefit of asking the driver for a position report immediately.
If the train was at a signal, the Driver gave the signal number. From a normal operational perspective that ticked the box. However, one serious accident revealed its limitations. The Driver survived the accident, and walked to the nearest signal to report what had happened to the Signaller and ask for help. The Signaller called the emergency services…but could only tell them the signal number - which of course, meant nothing to the emergency services. Operationally the Signaller knew everything he needed to know regarding the location of that signal in relation to other signals and junctions, but in terms of where, geographically, the signal actually was, or how you would get emergency services to the location, he has no idea. Crucial time was lost before the wreckage was found, and help provided to the casualties. One of the recommendations in the accident report was that every signal box must have a map, showing where every signal actually was, for use in such circumstances. If the train was between signals, as Vern says, there was really no way of knowing exactly where it was. If the train failed to arrive at the next signal box and you received no word, you set off (either on foot, or cautiously on a light loco) and kept going until you found it. There was more than one accident when a loco struck a train which it was looking for.
Suppose to an extent it was easier to find where the train wasn't and from that roughly estimate where it was in theory :P
I don't know about the UK, but in the US each signal box reported trains by telegraph, and later by telephone, as they passed. By the 1950s, even before cab radios were commonplace, the advent of CTC meant that control could track trains by the changes of auto block signals.
In the UK track MAS routes fully track circuited would pin down the location of a train a bit better but as the sections on some lightly used lines or where the signalling was put in on the cheap could be several miles long, still only a rough idea where the train was.
