Page 259 - 360.revista de Alta Velocidad - Nº 5

Maintenance. From asset management to direct cost calculation.
A key issue for the future of the HS Railways System.

Before presenting these methods, let's take a brief look at the development of this
problem. The first country to establish a separation between operation and infrastructure
management was Sweden in 1988, when it separated its former state railway authority into
two parts:

Statens Järnvägar (service operation), and Banverket (infrastructure management) . For
3
this reason, it is not surprising that the first investigation in this field was made in that country.
Subsequently, the number of studies has expanded, covering other networks, such as Wheat and
Smith (2008) for the English network. All approaches until 2015 follow the so-called econometric
model; in 2015, Smith et al. present a model in which the damage caused in the infrastructure
by different types of vehicles is analysed.

4.2 Methodologies

In order to assess correctly the amount of the fee, it is necessary to develop a methodology to
determine what expenses are incurred. The problem is therefore to establish a link between
the damage generated by a train, and the cost this entails for infrastructure. For this, we can
use different models, for which we will need to have a series of inputs that can come from
different types of analysis.

Wheat and Smith (2008) identify three different methodologies for determining directly
incurred costs: top-down approach, bottom-up approach, and cost allocation method. These
methodologies are explained in the following sections.

4.2.1 Econometric approach

The econometric approach, also called "top-down", is the determination of a global cost
function for the maintenance of infrastructure. In this perspective, the concept of direct costs
corresponds to the marginal cost, that is to say, to the increase of cost that is produced in
the maintenance when one train runs over it. To obtain this, a global cost function must be
established, which is done by statistical methods. Once this function is generated, the average
cost of maintenance caused by the passage of a train can be approximated as the marginal cost,
which is equivalent to that derived from the cost with respect to the number of trains running.
This method has been the most used to the date.

4.2.2 Engineering approach

The engineering approach, also called "bottom-up", is based on the application of any method that
allows to determine the concrete damages caused by a train and the subsequent maintenance
needs. By valuing the cost of these, the cost to pay for each circulation can be calculated.

Different types of trains will produce different types of wear on the infrastructure. For example,
the damage caused by a high-speed train will not be the same as by a freight train with a
high axle load. Therefore, in this approach, the damages produced by each type of train are
determined.
3 Subsequently, there have been more changes in the organization of the Swedish railways. Statens Järnvägar has been separated
into seven companies, of which four have been sold. The provision of passenger services (SJ AB) and goods (Green Cargo) remains
public. In terms of infrastructure management, the inspection functions (Järnvägsstyrelsen) have been separated from those of
administration, which in turn has merged with the Trafikverket. The maintenance of the infrastructure is the responsibility of a
subsidiary company, Infranord.

International Congress on High-speed Rail: Technologies and Long Term Impacts - Ciudad Real (Spain) - 25th anniversary Madrid-Sevilla corridor 257