Page 359 - 360.revista de Alta Velocidad - Nº 5

A railway culvert maintenance management approach based on risk assessment techniques

in order to overcome this issue. Maintenance investments prioritization will be determined
by the profitability of the proposed actions in every analysed culvert based on the nature
and entity of the observed pathologies. Thus, it is not only possible to prioritize the kind
of proceedings required at a specific time following economic criteria, but also analyse and
compare the profitability of a set of preventive actions to be carried out in a certain section of
the infrastructure or in the whole transport network.
The present document presents the risk assessment methodology proposed to obtain the
assets preliminary diagnosis and its suitability to perform global analysis on railway and road
infrastructures.

2. Methodology

The proposed methodology is based on the quantification of the asset risk level. The circumstances
that constitute failure of hydraulic structures, including culverts, can be defined differently
depending on the viewpoint of the analyst and purpose for the analysis. For the purpose of this
analysis, failure events are defined as those situations leading to partial or total railway traffic
disruption. Failure may range from structural collapse of any of the elements constituting the
culvert (culvert barrel, headwalls, wingwalls and auxiliary structures), to insufficient hydraulic
capacity to pass floods. The asset risk level is determined as the combination of the probability
of occurrence of each of the events leading to failure (failure mechanisms) and the impact or
consequences derived from this situation.

The asset risk level assessment requires a complete characterization of the culvert and its
surroundings, thus it is crucial to develop a regular inspection program based on field analysis,
including a detailed evaluation of the following items:

• Culvert barrels: including geometry and general condition assessment (related to structural
damage).

• Inlet and outlet structures: including general configuration, geometry and condition
assessment.
• Embankments: geometry characterization, general soil characterization and current
condition (presence of evident signs of slope instability caused by influx or piping) based on
visual assessment.
• Waterway: characterization of the waterway downstream the culvert outlet, including
shape and approximate geometry of the cross section.
• Adjacent areas: general determination of location and main characteristics of the nearest
elements to the culvert inlet or outlet that could be affected by an occasional instability of
the railway embankment or a structural collapse of the headwall.

The field assessment must be complemented with further desktop analysis in order to determine
all the required parameters to accurately evaluate failure probabilities and potential impacts
of the culvert failure. The information required in this case range from average data of railway
traffic intensity to the characterization of the waterway drainage basin. The aim of this work is
to provide a preliminary diagnosis of the current performance of all culverts inspected, so that
it is possible to prioritize the care level of each asset according to an objective parameter: the
asset risk level, quantified by the yearly average economic impact of the culvert failure.
Once the assessed risk level has been determined, the preventive actions to be carried out in
each case can be prioritized according to risk reduction criteria. According to the preliminary

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