Why trains and railroads play a big role in Proust's Search of Lost Time

Wondering why trains play such a big role in Proust's In Search of Lost Time, from the lonely sounds of trains in the distance at the start of "Swann's Way" through the numerous complex train journeys the various characters take, especially in the Balbec sections, and numerous discussions of railroad timetables - and the part I'm reading now in the Swann in Love section of Swann's Way, in which Swann tries to figure out what trains to take so as to "accidentally" run into Odette while she's away from Paris: it's possible (probable?) that Proust had some degree of Asperger's syndrome, in which timetables sometimes become an obsession, but I think railroads are also a symbol of the the time - of the half-century, roughly coincident with Proust's lifetime (1870-1920, give or take) when railroads were developed for personal use (not just freight and military) but before motor vehicles were prominent - railroads gave people in Proust's time a unique sense of possession of and access to the landscape - you could actually get around, pretty easily. Think of the huge difference between railroads in Proust and the interminable and difficult coach voyages in, say, Madame Bovary or Great Expectations. Proust has a strange way of describing what railroads mean to Swann: he refects not that they give him access but that they give him "authority," a very unusual choice of words but there is the sense that the railroad gives the traveler the right to the landscape, possession over it - just as the nobility was truly becoming marginal, a whole new bourgeoisie was rising with a sense of entitlement to a land far beyond what that could see or walk to: the contrast between the "ways" (walkways) in Proust and the railroad journeys. More on this topic in future posts.