Oh dear... so much wrong with this. Where do I start?
Firstly...
- Rail infrastructure, is capital spending. You spend the money once, and then you have the infrastructure and over the subsequent years you get a return on the investment. (Might not be much of a return if it's a particularly badly thought out scheme but a return nonetheless).
- Pensions are current spending. You spend the money. It makes people happy while you're spending it. Then the money is gone. And not only do you not get any ongoing return from it, but you then have to keep spending the same amount over and over again each year if you want to keep up the benefits. Unlike capital spending, you can't spend the money just once and then have the project completed.
You simply cannot compare the two and just swap money between the two types of spending in the way you're suggesting (well, not unless you want to go bankrupt). So saying that the Government could just spend the money on pensions makes no economic sense, no matter how much pensioners might deserve it.
Secondly, that meme. I've seen several similar memes that make out that pensions in the UK are vastly lower than pensions in most other comparable countries. Every one I've seen uses misleading statistics and in my experience, they are all easy to debunk if you take a bit of effort. In fact, as far as I can ascertain, pension levels in the UK are overall pretty similar overall to pensions in similar countries - the UK Government is not being unusually mean. And on this particular meme, it quotes lots of figures for the 'payout' without ever defining what 'payout' means, so the meme is already meaningless. Then there's that picture of Iain Duncan Smith, which has obviously been taken completely out of context to give the impression he's vindictively laughing at pensioners. I have no idea when that picture was taken but it's a fair guess he was laughing at some joke someone had made and wasn't thinking about pensions at all at that moment.
I really would urge people to think twice before they share these kinds of unverified memes on social media without sanity-checking and fact-checking them first. Whether they originate from the left or the right, they are very often completely misleading, often to the point of outright dishonesty.