But you can, with your influence, I'm sure, have underground lines put in.

These underground lines often had short above ground sections as well.

The 3.4-kilometre fully underground line was estimated to cost S$1.4 billion.

The underground line which connected these areas with the central station was not rebuilt either.

According to this plan, the first underground line was supposed to be opened in 1990.

The proposal involves the construction of an underground line across west London.

Though users of many underground lines at rush hour may question whether that point has already been reached.

The underground line is expected to be completed by 2020.

There are several different methods of building underground lines.

Future development could include an underground line directly to the airport.