Any hindrance we can put on the Finnish-Russian border to stop them just unloading 12 cars of fresh troops in the middle of the country is a good thing.
Of course, if it does go that far, tanks and trains can move rolling stock, rip up the tracks, blow up bridges and other infrastructure behind them if they're forced to retreat.
Conceptually? Nothing.
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.
> what's to prevent
Russian lack of logistical planning.
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
1524 - 1435 = 89
https://en.wikipedia.org/wiki/5_ft_and_1520_mm_gauge_railway...
> The difference between Finnish and Russian gauge is 4mm
This doesn't seem like it can be a goal given
> maybe in 2032 we can start construction
I mean unless the plan is to assume Russia won't attack until e.g. 2040 when construction will be complete && Russia can't implement multi-gauge trains that Spain is already using now?
And in any case, just as in computer security, a security posture does not need to be unassailable, it just needs to be expensive enough to deter the enemy. NATO countries (well, the ones that haven't already been compromised by Russia) will be happy to fund the gauge switch, as would the EU in general for the sake of greater economic integration. Meanwhile, it increases the costs on Russia and slows their advance. It's a win no matter what.
Following logic it also increases your own costs and wastes money that could've been allocated to produce weapons and other more effective preventive measures.
Or Kazakstan, although China might object there.
He's absolutely not harmless, but neither should we allow ourselves to be distracted by phony countermeasures against the Russian threat, like this gauge shift thing clearly is in my opinion.