The infrastructure spending is indeed mind boggling, but I have the feeling similar to their real estate glut that they are building too low quality and are making a grave mistake in this because they will be stuck with this infrastructure for the next decades (comparable with how the US is stuck with its aging airports, highways and congress centers).
The public infrastructure (especially the newer one) is actually quite decent even by Western standards. The private buildings are not, at least the old ones (actually they are quite bad). The Chinese government recently banned high-rises because of this. Many of these buildings are now a liability to the public.
