In Spain it's ongoing, very slowly, since the first international gauge high-speed rail line started operation in 1992.
It's a slow and quite annoying process. For example, to reach my region, trains from Madrid have to change gauge because my region still has the old one. Apart from spending around 10 minutes doing this, this has caused a lot of problems because it essentially means there is a single model of 300 km/h train that can make it here (others don't support gauge change) and to top it, said model turned out to be highly unreliable. This created a lot of political tension because of course we wanted 300 km/h trains like other regions, but now we're stuck with these lemons and our regional politicians push for gauge change, but the national government doesn't want to do it yet as it affects freight trains.
I hope at some point we get the change done in the whole national network, although generally it moves at a glacial pace. It makes sense to have seamless connection with France and the rest of Europe, and to be able to use the same trains everyone else does.
You lost me at ‘single model of 300km/h train that can make it here’
Meanwhile here in Australia our “fast rail” trains go 160km/h. Unless it’s over 32 degrees, then they slow down. And if it hits 36 degrees they slow down even more (90km/h)
I suppose it's difficult to make that mistake because plane tickets are to cities, not countries as a whole.
As a real story, I knew a guy who had a B&B near a beach called San Francisco, in Spain, and he regularly had to cancel bookings from people who thought it was in the US city of the same name, though :)
As an armchair expert, I think it turned out badly because they had to develop cutting-edge technology (no trains with that top speed and support for gauge change existed before, and it also has other quirks, like being uncommonly wide to support five seats per row) but, at the same time, make it very cheap (the project started in the context of harsh austerity in the years after the financial crisis, with PIGS accused of overspending, etc.). They promised too much for the budget and ended up delivering a half-baked train. At the beginning, a year ago, it was a disaster (lots of incidents with trains stopping mid-way, etc.), now they seem to be ironing out the problems and things are getting better but they're still much more unreliable than other trains.
I hope at least the lessons learned help towards making a better model in the future.
It's a slow and quite annoying process. For example, to reach my region, trains from Madrid have to change gauge because my region still has the old one. Apart from spending around 10 minutes doing this, this has caused a lot of problems because it essentially means there is a single model of 300 km/h train that can make it here (others don't support gauge change) and to top it, said model turned out to be highly unreliable. This created a lot of political tension because of course we wanted 300 km/h trains like other regions, but now we're stuck with these lemons and our regional politicians push for gauge change, but the national government doesn't want to do it yet as it affects freight trains.
I hope at some point we get the change done in the whole national network, although generally it moves at a glacial pace. It makes sense to have seamless connection with France and the rest of Europe, and to be able to use the same trains everyone else does.