Page 534 - 360.revista de Alta Velocidad - Nº 6

González Franco, Ignacio

1. Introduction and methodology

1.1 Planning a high speed line

The construction of a new transport infrastructure, such as a railway high-speed line, requires
an enormous mobilization of resources, has a long lifetime but the alternative uses of this
investment are very few. Consequently, this kind of investment is always preceded by a rigorous
analysis and occasionally also by a public debate in order to ensure the best possible results.
Normally, the final decision made about the construction of a railway infrastructure is based on
a Cost Benefit Analysis (CBA) methodology, supported by different indicators (i.e. NPV, IRR…)
which, depending on the value obtained, will support or reject the final decision of building the
infrastructure.
The methodology (CBA) is based on intermediate results obtained from different models
(exploitation cost models, revenue models…). These intermediate models also process different
input parameters, which usually are: (i) characteristics of the infrastructure (maximum speed,
slopes, etc.), (ii) socio-economic variables (such as population, GDP per capita…), (iii) train
parameters (e.g. maximum speed, architecture…), (iv) service variables, as load factor,
frequency, and (v) unit costs. Thereby, it can be said that the final decision made, in an indirect
manner, is influenced by the value of a set of parameters (input parameters), and depending on
the value they take will increase or decrease the profitability of the project.
Among the input variables capable of increasing or decreasing the profitability of a HS project,
it can be stated that the maximum design speed of a railway line is of a major significance to
the final output and to the socio-economic profitability, due to it has an influence on each and
every of the parameter that feed a CBA (see Figure 1).

Figure 1. Effect of the speed on the economic and financial profitability.

As well as, many others manageable parameters are, occasionally, field of study within the CBA
(i.e. fare, frequency…); maximum design speed usually is a pre-defined value and previously
established to an economic appraisal. If real high-speed lines currently in service or under
construction are studied, maximum design speed is practically the same (300km/h or 350 km/h)
all over the European high-speed networks.

Maximum design speed plays a crucial role in a framework in which the efficiency and the social
benefits are essential. A higher design speed implies higher investment costs and, sometimes,
implies small increases in exploitation costs, but it also brings journey time reductions and,

532 360.revista de alta velocidad