You shouldn't be packing people like sardines. If your subway is that full then you should be adding more trains, or building more lines to ease congestion. (depending on your cities exact situation). In the US we have made building for a reasonable price impossible and then say it is impossible to fix the problems, but it shouldn't be like that.
Building more lanes does work - but people misunderstand induced demand. Really induced demand should be called fixing suppressed demand. If you get induced demand it means you need a lot more lanes. We can't afford the 50 layers of highway bridges needed to build enough lanes, but transit is a lot more space efficient and so we could afford it.
