Whether or not it was the intention, that's been the effect. In a small town I grew up in, a commuter train line was installed and the place started to grow. They implemented minimum two acre lot sizes for all new construction; not many can afford such a huge lot, nevermind building the house afterwards.

I haven't found a citation on this, but I'm pretty confident that the folks who gave us explicit racial segregation said some pretty terrible things about poor people that I'll be able to cite. Unfortunately, the time I can spend on this is limited.