My take as a resident...
RENFE commuting (and regional) trains: to be avoided if you can!
Those trains are simply not reliable these days. We are having a lot of problems for different reasons, mostly political ones involving power struggles between Catalonia and Spain, but also because of major ongoing infrastructure works that never seem to be finished. The result is that the railway system operated by the Spanish company RENFE has become highly unreliable.
It has been like this for years, but over the past three or four years the problems have skyrocketed. All you need to do is look through newspaper headlines from recent years to find a constant stream of daily disruptions. The result is that RENFE’s rail network in Catalonia is now in shambles.
There are trains every day, of course. What you never know is whether they will be late, whether the journey from say Tarragona to Barcelona will take one hour or considerably longer, or whether you will suddenly have to switch to a replacement bus halfway through. And yes, occasionally, you do manage to complete the journey without any disruption.
... but if you must...
And to make matters worse, on top of running a terrible service, their passenger information systems are notoriously awful. You never really know what is happening, when it is happening, how long it will last, or what you are supposed to do next.
Thankfully, there's a website -unofficial, of course- built by a set of volunteers (regular commuters) which uses RENFE’s own open data, which shows real-time information about daily disruptions affecting train services from this company in Catalonia. Many regular commuters use it. A small note: it is only available in Catalan, so you may need Google Translate. You will notice that the information is genuinely updated in real time, but delivered with a subtle layer of sarcasm. That is not accidental. It is simply a very Catalan way of dealing with things.
So, either you organise your plans around intercity bus services instead, and there are plenty of them, or I would stay closer to Barcelona. Unless, of course, being on holiday means you do not mind a certain amount of uncertainty or the "occasional" (?) long delay.
Now, if you decide to stay in Barcelona or nearby and visit Tarragona just once (or vice versa), the chances of running into serious disruption are obviously lower than if you base yourself in Tarragona and plan to travel to Barcelona regularly. One unreliable journey is a risk. Having to rely on the same unreliable service several times is a different matter altogether.
What about relying on FGC instead?
It is also worth knowing that there is a second rail network, run by the Catalan government, called FGC. It operates several lines, mainly to the north and north-west of Barcelona. For example, if you decide to visit Montserrat, this is the network you would use. FGC is a 10/10 service: efficient, punctual, modern and highly recommendable.
So, if you were to choose a base in one of the towns or cities served by these lines, it does not really matter how far you are from Barcelona, since you will have a very reliable means of transport. The catch is that the two networks barely overlap. For example, if you prefer to stay in Tarragona, there is no FGC service connecting it to Barcelona.
Enjoy!
