TGV tests the trains and helps develop sound barriers to protect the surrounding area. There are two major drawbacks to this technology. One is money. High speed rail links are expensive to build and maintain. Another consideration is land use.
Any new construction involves the destruction of natural landscape.
A small road is preferable to a railway because a road can have steep gradients and tight curves. A railway has to be much more straight and level, and this usually involves massive cuttings and embankments which can severely disrupt the landscape. However, a railway takes up far less room than a Freeway, and thinking more about the long term, a railway can handle between 25 and 100 times more passengers than a road given the same amount of room. This means that once a railway is built, it should be able to handle future levels of traffic without the need for new links in the future. Airports are only applicable to the longer distance connections.