Lötschberg South Ramp at Hohtenn

Because the Lötschberg Base Tunnel isn't double-tracked along its full length, so its capacity stays limited. What doesn't fit through the flat line continues to run over the mountain – and on top of that, the mountain line serves the villages on the hillside that would otherwise have no rail connection at all. The difference from the Gotthard is noticeable here: on the Lötschberg, the mountain line kept more of its traffic.

For the whole route heading east you should allow a full day, or rather five to seven hours with photo stops. Anyone who just wants to see the first structures reaches the first viaduct from Hohtenn station in a good hour and can walk back in the same time. The path is marked, but continuously hilly and exposed in places.

Mostly passenger trains of BLS, above all the RABe 535 Lötschberger. On top of that come freight trains when engineering works are under way in the base tunnel or capacity runs out – then you see locomotives such as the Re 465 ahead of heavy trains on the mountain. Special and heritage trains also like to use the line.

Yes. Sturdy shoes with grip are essential on the high trail, along with water for several hours, sun protection and a windproof jacket. There's no shade, nowhere to eat and no water point over large stretches. What else belongs in the rucksack is listed in the spotting equipment checklist.

By train, over the mountain line itself – Hohtenn station sits right at the start of the high trail. From the north you arrive via Bern and Spiez, from the south via Brig. This is one of the few mountain spots where you can work entirely without a car: you take the train there, walk along the line and board again further down.

In the morning. The line sits on the north side of the Rhone valley and faces south, so it gets sun all day – but the distant views over the valley are considerably clearer in the morning. As the day goes on the haze increases and the mountains on the far side lose contrast. In late afternoon the light turns soft, but the viaducts sit partly in their own shadow.

Only to a limited extent. The first stretch from Hohtenn is easily manageable, but further east there are exposed passages above the valley slope. Anyone uncomfortable with that should turn back after the first viaduct – not a bad decision, since one of the best subjects sits right there anyway. For a relaxed start with family, a flatter spot suits much better.

The Gotthard is about spiral tunnels and staggered levels; the Lötschberg is about a single line running as a balcony along the rock face. At Wassen you see the same train three times, here you see it once – but in front of viaducts and four-thousand-metre peaks. The South ramp at Giornico sits in between: open like the Lötschberg, convoluted like the Gotthard.

Yes, if you have two days. From Brig the Simplon axis continues into Italy; the border station of Domodossola is reachable from there in a manageable time and brings you the vehicle mix the mountain line doesn't provide. That way you combine a landscape day with a sighting day.

No. The structures, their access ways, embankments and portal areas are railway property and therefore off-limits. The high trail is deliberately routed so that you get every subject from public ground – any step beyond that is unnecessary and dangerous. Why this applies even with a thin timetable is explained in the article on safe distances at the track.