that's amazing that there is no fully double track rail line from coast to coast in the USA. for a country with 300 million people i would have expected most intercity rail lines to be double track look at the east and west coast lines mostly single line i bet with chronic track congestion.
In Australia some rail route have 3 or 4 lines just to cope with the demand. but we have alot of single line but there are very long distances between stations and only 22 million people in Australia.
but all the major cities are linked by rail some with 3 or 4 trips a day.
Who pays for the construction of railways in the USA?
State governments or National government. In Australia its mostly state governments
Does the USA suffer from break of gauge?
i.e. one state system having standard gauge and the other meter gauge. thus preventing through travel for both passenger and freight.
This is a Huge problem in Australia but rail still well used for example a train from Sydney cannot travel to any ware north of Brisbane due to the width of the rail track being 435 millimetres closer together in Queensland.
What is the average line speed and track condition in the USA on long distance routes?
In Australia it is 120 kph (70 mph) on long distance except in south west Western Australia and Queensland where it is up to 200 kph (120 mph).
Does the voting public make a big issue of mass transit and rail freight in the USA?
Mass transit is a headline creating issue in both rural and urban Australia. State Governments can win an election on this issue.
Just for peoples interest if they cannot picture the Australian rail network hear is a very good interactive map.
http://www.railpage.org.au/railmaps
To get a more detailed map click on one of the 7 states of Australia