Rail is far more efficient than any of the other current forms of ground travel. Air travel is for speed, not for fuel conservation. People talk about conservation, but what they really want is speed.

According to the Association of American Railroads, a freight train can haul one ton of freight coast to coast (~3,000 miles) on seven gallons of fuel; a semi-truck would take 27 gallons to haul the same weight the same distance.
Railroads: Green from the Start

An article by UK Parliament shows that
Passenger rail (diesel) w/90 people aboard= 182 mpg/per passenger
Buses carrying 9 people (avg # per load) = 98 mpg/per passenger
Air (long haul) w/300 people = 66 mpg/per passenger
Air (short haul) w/100 people = 40 mpg/per passenger
UK Passenger Transport: Fuel Consumption

Sue