And guess what's often hotly contested. Noise barriers tend to draw complaints because they ruin the sightline, are either ugly from the start or end up being "decorated" not by good art but quick throw tags. And landlords are often too much penny-pinchers to install decent windows unless you legally require them to, which is often impossible for already constructed buildings. The landlords don't have to live with the noise after all, and in overheated housing markets people are forced to live in what they can get.