cant Imagine it’s much fun going into a long tunnel as one passes by. Especially ones with a station stop at the other end like Sutton or a red like Bangor. Need to get your breaking points bob on.
I’ve never passed one in a long tunnel though. I can only answer for normal running and no, it’s never been an issue, even for a relatively new driver like me (4 years). You’ve got various safety systems like AWS & TPWS+, you can use these as markers like you would in the fog to determine how far from a signal you are. By the time it’s of any issue the smoke/steam has cleared and you’ve already forgotten about the steam train. A bigger issue is with the few idiots trespassing to get nearer to them and having close calls. But that’s for another thread.
I'm old enough to remember the 1960's in West Yorkshire, when steam and dmus were using the network.
A particularly difficult spot was Bowling tunnel at the top of the incline from Bradford Exchange on the ex L&Y route to Halifax and the Calder Valley, where sometimes a dmu going into Bradford would meet a heavy steam -hauled train having come up the bank.
The steamer would usually have been banked as far as Bowling Junction, and the banker would be sitting near the tunnel mouth, ready to be crossed-over to return to Bradford after the dmu had passed, and so emitting some smoke at the tunnel mouth.
The steamer would be accelerating through Bowling tunnel, filling it with smoke, into which the dmu entered going the opposite way. From the front seat of a dmu you could see the driver's difficulty, especially if he'd been cautioned at the mouth of the tunnel. It was full of smoke, and it depended soley on his sensing when he was nearing the end, and edging forward ever so slowly, as the signal protecting the junction was right outside the tunnel. He had my full admiration, as there was no AWS in those days, and to emerge too quickly could have resulted in a spad.
In most cases, the signal would have cleared by the then, and it was a case of a sigh of relief, slip into second gear, and accelerate.
But a very testing situation, nonetheless.