Well, the original train tracks not ony went from large town (dense, highly occupied area!) to large town (dense, highly occupied area!) but they were specifically laid out to go through as many small towns as possible on the way - because the trains WERE local and DID carry as much freight and passengers on their "local" runs as possible. At EVERY town along the track, the train station was as close to the center of town as possible, because that was where the people are, the cargo is, and where the transportation was needed. Is still needed.
Along the way, the tracks ran as short as possible, ran as flat as possible, crossed each valley, ridge, and river as short and flat and direct as possible: which IS the way the roads went - or if the tracks were going before the roads did (which also happened) then the roads parallel the train tracks because that was were the traffic and people wanted to go - as short, flat, and direct as possible works both ways.
The potential destruction by a [train wreck -> gas or chemical release - explosion] is real.
BUT the explosion release area (the safety area around a potential explosion) needs to be too large to be isolated to try to minimize hazards of potential explsoions. And, though multi-billion dollar "blast walls" (or a submerged track below ground level) might help if the blast were small enough, then the enviro impact would be another 10x billion dollars. Worse, any release of "gaseous" (explosive or toxic!) substances WILL NOT be contained by the blast walls. (A fire would not be contained either, though a fire by itself would not be as hazardous as a fire -> explosion combination. But the blast walls would not stop the fire -> explosion of a nearby train car. )
So the whole attempt is expensive, useless, and meaningless. But sounds good. To soebody who can make a name (or get money!) by "trying" to do something - which ends up useless and expensive by using somebody's else's moeny.
Which is why it is a typical government "investigation" by a nanny state for nanny-staters catering to nanny-stators.