Over 6 weeks its early july, holidays have started and these trains are quite small and often in fact the only trip/day for these (not overly much asked for) connections. But I recall this ´tren´ a yr or 2-3 ago to be 1 loco+ 1 car-with <10 pax in (lve from Bilb). I also recall that to do Bil-Sal there must be more as just 1 connection/day. You have to pay 2x the fee, as every train is apart.

The MAIN bottleneck are the direct AVE Bcn-Andalucia, as there are just 2/day and anyone+his grampa+ma seems to want to use these on a pass.

The site of RENFE, the spanish, should of course, no need to ask, be the best to trust for best actual situation.

Thanks @mcadv , I think I'll just see what happens. The only problem I see so far is that if anything goes wrong all my other reservations (including hotels) will be a miss and likely not cancellable. Hopefully my travel insurance won't be too strict.

Pff, if I had knew beforehand it was this complicated I'd stick to my original plan of flying to several cities (yes, I always pay for CO2 admission), but a friend warned me about flight cancellations, so I thought let's try the train. To avoid that bottleneck you mention, I think I'll fly that leg anyway. Trains are nice (I used to be a conductor several lifes ago , but this…….

RENFE are generally a pain in the lower backside, especially for pass reservations.

Here's an overview of booking possibilities for domestic trains in Spain.