It's less about what the Russians can do and more about how fast European and NATO countries can move assets to a potential invasion front line; as it stands, they're slowed down at the borders needing to switch to the different gauges.
But building such trains, at scale, takes a load of resources. Resources which could otherwise be used to build tanks, guns, missiles, and similar high-priority products.
I would also imagine that large-scale retrofitting of traincars with variable gauge adaptations is something that would be hard for foreign intelligence services (including the Finnish one to miss) - and would then serve as a signal that Russia is indeed preparing for an invasion.
The difference between Finnish and Russian gauge is 4mm
IIRC the diff to European standard is closer to 10cm, still doable but a hurdle compared to just driving a trainload of troops to the middle of Helsinki it's a bit harder
First sentence from the article:
The Finnish government has announced the conversion of its rail network from Russian gauge (1,524 mm) to European standard (1,435 mm).
The really annoying thing is that it's too close for "simple" dual gauge rails (e.g. 1435 + 1000); 1435 + 1524 is possible and in fact exists (e.g. the one single SE-FI railway bridge that exists is dual guage: https://openrailwaymap.org/?style=gauge&lat=65.8273204537081...), but AFAIK it's expensive because the mounts interfere and need to be quite custom.
Even if you were to 4-rail every line, you'd potentially run into loading gauge issues (you would have to offset the current centre of the bogies, go too far one way and you collide with platforms, too far the other way and you collide with oncoming trains)
Bleh, but kinda confirms my point too. I do think there are some 3-rail setups in other border regions though? I should check… then again it doesn't matter that much if it's 3 or 4.
As for the loading gauge, yes, of course. On the plus side, this is Finland, most of the lines is in the middle of nowhere and single track even. Maybe the best option for them is to just build 1435 in parallel whereever possible, and just merge where not otherwise practical (bridges, tunnels, populated areas & stations). I don't even think it's that infeasible considering Finland's layout. I'd wager there are only a handful of specific locations that need expensive work.
> Train tracks are normally not precise to within 4mm anyway
Yes they are. Of course practical tolerances including allowances for wear and there are large enough that things can be made to work, but in terms of nominal construction tolerances for example, 4 mm can easily eat up all your construction tolerances or even exceed them.
I obviously don't have a in depth knowledge of Finnish rail, but have you ever looked at rail in the US? I can show you tracks with completely missing ties. Tracks that move vertically by a foot when the train goes over them. Tracks that visually snake all over the place. The difference is made by slowing down the train. Derailment at 3 mph rarely matters. The biggest risk is the conductor doesn't know it happened & continues to drag the car along the tracks
Where? Finland specifically, or elsewhere? Both my local tram system in Germany as well as DB as the national infrastructure operator in Germany have construction tolerances of only +/- 2 mm. Maintenance tolerances on the other hand can be quite a bit larger, at least in the plus direction (on the order of 15/20/25 mm).
