Highways and rail create different kinds of disruption in neighborhoods. Highways constantly have traffic, creating noise and pollution all the time. Railroads are mostly quiet, with loud traffic in short bursts.

Passenger railroads are narrower than urban highways. The US-101 freeway cuts through Echo Park and Westlake in Los Angeles, taking up as much as 330 feet of width, counting on/off ramps. California HSR has trench sections specced as narrow as 72 feet[1], and most of its urban rights-of-way are under 100 feet wide.

Walking next to the 101 in Echo Park you can see how it so starkly divides what was once a single connected neighborhood. The light rail lines (about ~40-50 ft to cross) in other neighborhoods don't give that impression.

[1]: https://www.hsr.ca.gov/wp-content/uploads/docs/programs/eir_...