Socialist (or Socialism) is not really a Political left or right issue; China and Russia are BOTH not left-leaning, they are the very definition of "Nationalist" (I mean, I don't think anyone would call Russia and China left-wing), but both are Socialist countries because both Countries control everything via SOE. This is the point most people don't understand. That's what we studied in Politics called "Perceived Socialism"
The Political Left used to be associated with socialism because of the becuase they share some similar ideology (like Materialist, for example) but what hurt most is the association of Nazi Germany with Socialist ideology, which is an absolute fascism with left-wing ideology, but those were not about Governmental Ideology, but rather fiscal socialism, "for you to have a strong Germany, people need to give up their ownership/procession" that's the Nazi Socialist idea.
Left-leaning policy is built for people, while right-leaning policy is built for the country. Left-leaning people in the West usually call for money to spend on people instead of government functions, free healthcare, free education, and unemployment benefits. On the other hand, right-leaning people suggest that Citizens should take care of themselves, and money should be spent on government functions, like defence, diplomacy, national security, and foreign policy
As for the High Speed National railway network, well, this is not a topic for socialism, but I don't see how that's going to work, we don't have enough people between city center to justify such a project, the only way I can see that being build in the US is like China when they are using their spare resource to boot up part of their economy, they need to keep building stuff to justified the amount of Steel use which in turn protect the steel industry. Otherwise I don't see any way US would subsidise a National HSR network.