High speed rail (HSR) is usually regarded as services operating at 250 kmph or more, and these invariably require construction of new purpose-built lines. According to the International Union of Railways (UIC), by 2012, a total of 13 000km of such lines had been built worldwide, half in Europe and half in Asia. China had the largest network at 3 426km, whilst Japan, France and Spain all had over 2 000km. There are plans for a further major expansion, with the European Commission calling for a trebling of the kilometrage in Europe by 2030.Yet high speed rail is an enormous investment, with a typical 500km line costing 6-12Bn euros in 2004 prices (Euros 12-24 Bn per km) (de Rus and Nash, 2009). It is necessary to consider very carefully in what circumstances such an outlay is justified.