ETH Library
Estimating and communicating the
risk of neglecting maintenance
Journal Article
Author(s):
Adey, Bryan T.; Martani, Claudio; Papathanasiou, Natalia ; Burkhalter, Marcel
Publication date:
2019-06
Permanent link:
https://doi.org/10.3929/ethz-b-000354735
Rights / license:
Creative Commons Attribution 4.0 International
Originally published in:
Infrastructure Asset Management 6(2), https://doi.org/10.1680/jinam.18.00027
Funding acknowledgement:
636285 - Decision Support Tool for Rail Infrastructure Managers (SBFI)
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Estimating and communicating the risk of
neglecting maintenance
Bryan T. Adey PhD
Professor and Head of the Infrastructure Management Group, Institute of
Construction and Infrastructure Management, ETH Zurich, Zurich,
Switzerland
Claudio Martani PhD
Research Associate, Institute of Construction and Infrastructure
Management, ETH Zurich, Zurich, Switzerland (corresponding author:
martani@ibi.baug.ethz.ch) (Orcid:0000-0002-9039-0908)
Natalia Papathanasiou Dipl.-Ing, MSc
Research Assistant, Institute of Construction and Infrastructure
Management, ETH Zurich, Zurich, Switzerland
(Orcid:0000-0001-7781-051X)
Marcel Burkhalter MSc, ETH CEng
Research Assistant, Institute of Construction and Infrastructure
Management, ETH Zurich, Zurich, Switzerland
(Orcid:0000-0003-3017-1751)
The difficulties of engineers and managers agreeing on how to invest in infrastructure maintenance stem from a basic
inability to communicate with each other. This leads to the suboptimal management of infrastructure. Luckily, this
situation can be remedied by engineers learning how to communicate their concerns in a way that managers can
understand, so that they can clearly see whether a proposed action needs to be taken or can be deferred. This paper
shows, with the help of a realistic example, in terms of infrastructure, methodology and techniques, how this can be
done. The proposed approach, although upon reading is perhaps intuitive, is starkly absent in the literature in the field
of infrastructure asset management. In the proposed approach, it is demonstrated how to improve the traditional
approaches used by engineers to communicate to managers through (a) the quantification of the level of service as
seen by mangers, (b) the modelling of how infrastructure might not provide the required level of service and (c)the
way of showing how intervention programmes can affect the provision of service, both now and in the future.
Introduction
Management of infrastructure often involves engineers and
managers. Engineers, who are assumed in this paper to be those
people responsible for deciding exactly what is to be done with
pieces of infrastructure, are people with a technical background
who are concerned about the details of how infrastructure
functions, how it might fail and the processes that can cause this.
Managers, who are assumed in this paper to be those people
responsible for deciding how to allocate money for entire
portfolios of infrastructure objects including across districts and
regions, are people with a business background who are
concerned with ensuring that infrastructure can meet the demands
of it. Engineers and managers are working on the same team. Due
to their different backgrounds, however, they sometimes have
difficulty communicating with each other. This needs to be
changed. The approach proposed in this paper, regardless of the
infrastructure analysed or specific methodology or techniques
used, bridges this gap. The proposed approach, although upon
reading is perhaps intuitive, is one that has not yet been proposed
in the field of infrastructure asset management.
In order to understand how this can be done, one needs to have
a common understanding of infrastructure and infrastructure
management. Infrastructure, at least in this paper, is considered to
be the fixed physical objects that are needed to provide a service –
for example, to allow people to travel between two cities within an
hour. Infrastructure management is the process used to ensure that
the infrastructure provides the service expected from it – for
example, planning and executing interventions to prevent bridges
from collapsing on the road between the two cities. The key for
engineers and managers to understand each other is to focus on the
service provided by the infrastructure. If it is accepted
that infrastructure exists only to provide service, it becomes
impossible to make reasonable decisions pertaining to infrastructure
without explicitly considering it. Indeed, this is why there is room
for improvement in many of the discussions between engineers and
managers, as engineers do not frame their arguments, normally, in
the language of why infrastructure is there. Instead, they focus on
parts of the big picture, talking often about reliability, availability
and safety. These parts are by all means important, but they are
only proxies for what really matters – that is, service.
In order for engineers and managers to communicate and to
understand the contents of this paper, it is not only the definitions
of these words that need to be clear, but also how they relate to
service. The definitions used in this paper are given in Table 1.
These definitions were chosen by the authors to facilitate the
writing of the paper. Of course, other definitions for these words
are possible, but these ones nicely and clearly link them to the
point of having infrastructure – that is, to provide service. Other
definitions would not change the approach proposed in the paper
or the ability to demonstrate its effectiveness. If other definitions
or other proxies – for example, affordability – are used, they
should also be tied to the service provided. Many discussions
between engineers and managers end in frustration in the absence
of clarity in these matters.
Literature review
There has been in the past an extensive and growing amount of
literature on decision making with respect to infrastructure. This
can be grouped as literature focused on (a) technical aspects, such
as reliability, availability and safety; (b) multicriteria decision
109
Cite this article
Adey BT, Martani C, Papathanasiou N and Burkhalter M (2019)
Estimating and communicating the risk of neglecting maintenance. Infrastructure Asset
Management 6(2): 109–128,
https://doi.org/10.1680/jinam.18.00027
Research Article
Paper 1800027
Received 10/05/2018; Accepted 07/11/2018
Published online 30/11/2018
Published with permission by the ICE under the
CC-BY 4.0 license.
(http://creativecommons.org/licenses/by/4.0/)
Keywords: maintenance & inspection/
management/risk & probability analysis
Infrastructure Asset Management
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analysis, which is focused on weighting more than one criteria in
often subjective ways; and (c) cost–benefit analysis. The literature
in all three categories contains text stemming from research and
from practice in the form of guidelines or supporting software.
Some of the most representative literature in each category is
presented and discussed in the next three sections.
Technical aspects
There is in literature an abundance of examples where justification
for infrastructure decisions are given based primarily on technical
aspects, which are essential used as proxies for providing service.
In every case, the quantification of how service might be affected
would enable better decisions to be made. A few of the examples
found in literature are given in Table 2, which includes, per
example, the technical criteria used, the decision made and an
exampleimprovement.Table2istobereadasfollows:itis
reported in Calle-Cordon et al. (2017) that the technical criteria
reliability, availability, maintainability and safety can be used to
determine the interventions to be executed on switches and
crossings. An improvement in the determination of the interventions
to be executed can be obtained by additionally quantifying the costs
of lost service in any situations when they might occur. For each
reference, only one example is given. By following the proposed
approach, such improvements would be ensured.
Multicriteria decision analysis
There is in literature an abundance of examples where
justifications for infrastructure decisions are given based on the
results of multicriteria decision analysis. Some of these works
assign values to multiple technical aspects, some combine
technical aspects and estimations of level of service and some
combine estimations of the level of service without reverting to
direct valuation of the levels of service – that is, costs. In every
case, a direct valuation of how the infrastructure might not
provide service would enable better decisions to be made. A few
examples of each of these are given in Tables 3 and 4, which
Table 1. Proxies
Proxy Definition
Availability The amount of time that the travel time costs are below the maximum allowed travel time costs divided by the total time
Reliability The probability that the costs will be lower than the maximum agreed on costs
Safety The probability of occurrence of accidents in which there are injuries or fatalities multiplied by the unit value of the injuries and
fatalities
State The physical condition of the infrastructure
Table 2. Examples of technical aspects used as proxies in infrastructure decision making
Reference Technical criteria Decision made
An improvement
would be to quantify
additionally …
Calle-Cordon
et al. (2017)
Reliability, availability, maintainability and safety Interventions to be executed on
switches and crossings
Costs to users of lost service
Patra (2009) Reliability, availability, maintainability and safety Interventions to be executed on
railway infrastructure
Costs to users of lost service
Zio et al. (2007) Reliability of objects, delays due to speed restrictions
caused by deteriorated conditions and interventions
Interventions to be executed on
tracks
Risks related to delays
Jaedicke et al.
(2013)
Probability of being hit by a landslide Rank of objects for intervention Costs of being hit
Liu et al. (2014) Probability of collision between cars and trains at level
crossings
Rank of level crossings for
intervention
Costs of travel delays in
case of collisions at level
crossings
Jafarian and
Rezvani
(2012)
Probability of derailment, the condition of objects Rank of objects for intervention Costs of possible accidents
and traffic interruptions
Peterson and
Church (2008)
Consequences on network operation in terms of traffic
flow
Rank of bridges and tunnels for
intervention
Costs of losing network
operation
Kurauchi et al.
(2009)
Consequences on network operation in terms of traffic
flow
Rank of links for intervention Risks related to network
operation
Fecarotti et al.
(2015)
Probability and duration of loss of network operation Rank of railway tracks, switches
and stations for intervention
Risks related to network
operation
Chang and
Nojima (2001)
Consequences on network operation in terms of traffic
flow
Estimate infrastructure disruption
and restoration costs after
earthquakes
Risks related to network
operation after
earthquakes
Sun and Gu
(2011)
Roughness, deflection, surface deterioration, rutting, skid
resistance
Road interventions to execute Costs of reductions in
service due to increased
roughness
110
Infrastructure Asset Management
Volume 6 Issue 2
Estimating and communicating the risk of
neglecting maintenance
Adey, Martani, Papathanasiou and Burkhalter
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include a summary of the criteria used, the decision made and an
example improvement. Tables 3 and 4 are to be read as follows: it
is reported by Carretero et al. (2003) that the probability of failure
multiplied by the costs of restoring the infrastructure can be used
to determine which interventions to be executed on tracks. An
improvement can be obtained by additionally quantifying the
costs of injuries, fatalities, damaged equipment and downtime due
to failures when they might occur. For each reference, only one
example is given. By following the proposed approach, such
improvements would be ensured.
Cost–benefit analysis
There is in literature an abundance of examples where justification
for infrastructure decisions are given based on the results of
cost–benefit analysis. These works often attempt to quantify all
effects on service by assigning to them either costs or utility. They
often, however, do not cover all important aspects of service.
A few examples of each of these are given in Table 5, which
includes a summary of the costs and benefits used, the decision
made and an example of service not covered. Table 5 can be read
as follows: it is reported by Peng (2011) that the decision of how
to group interventions on tracks can be made by taking into
consideration the costs of intervention and the costs of network
operation. An improvement, however, would be to take
additionally into consideration accident costs. For each reference,
only one example is given. By following the proposed approach,
such improvements would be ensured.
Summary
The literature review shows that many people are concerned with
making the right decisions with respect to maintaining infrastructure.
It also clear, though, that everyone is looking at only part of the
Table 3. Examples of multicriteria decision analysis in infrastructure decision making (1/2)
Reference Technical criteria Decision made
An improvement would be to
quantify additionally …
Carretero
et al. (2003)
Probability of failure multiplied by the costs of restoring the
infrastructure
The interventions to
be executed on
tracks
The costs of injuries, fatalities,
damaged equipment and
downtime due to failures
Stein et al.
(1999)
The probability of scour at bridge foundations, cost of
maintenance, cost of passenger delay
The rank of bridges
for intervention
The costs of injuries and fatalities
due to bridge failures
Cheng and
Tsao (2010)
Reliability, travel time, passenger safety, quality of service,
intervention costs
The interventions to
be executed on
rolling stocks
The costs of injuries and fatalities
due to bridge failures
Celebi et al.
(2008)
Quality of service, travel time, spare part costs, storage costs The interventions to
be executed on
tracks
The costs of lost quality of service
Ebrahimnejad
et al. (2012)
Staff required, project duration, fit with company fit, with
objectives and policy, fit with budget, risk/return ratio, fit with
regulations, fit with standards, fit with terms of contract,
ability of management to execute, ability to avoid conflicts,
contribution to environmental protection, contribution to
health and safety, knowledge regarding the technology
to be used
The track to be
installed
The costs of injuries and fatalities
due to heavy rain
Table 4. Examples of multicriteria decision analysis in infrastructure decision making (2/2)
Reference Technical criteria Decision made
An improvement
would be to quantify
additionally …
Caterino et al.
(2006)
Service interruption during interventions, cost of
construction; cost of interventions
The seismic retrofitting
interventions to be executed on a
reinforced-concrete structure
The costs of service
interruption
Dawotola et al.
(2009)
Externalities, corrosion, operational errors, structural
defects, cost of interventions
The design, construction,
inspection and maintenance
strategy for petroleum pipelines
The costs of lost service
due to deterioration
Frangopol and Liu
(2007), Liu and
Frangopol (2004)
Costs of intervention, safety, condition, environmental
impact
The bridge intervention strategy Failure costs
Guhnemann et al.
(2012)
Costs of intervention, safety, environmental impact The road intervention strategy Failure costs
Guhnemann et al.
(2012)
Importance of the project and the sector, cost of
intervention and suitability of finance, execution and
operation, probability of failure and consequences of
failure of the infrastructure
The urban infrastructure projects to
finance
The costs of delays and
accidents
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problem, either by not explicitly relating things to the service
provided or by not capturing all of the relevant service provided.
This means that when they present their ideas to a manager, the
manager , presented with an incomplete picture, loses confidence in
what it presented and knows it does not fully represent what they
care about. This forces or enables them to revert comfortably to his
own preformed opinions. This leaves frustrated engineers, on the less
serious side of things, but also to managers making suboptimal
decisions with respect to their infrastructure, on the more serious side
of things. The latter can lead to unnecessary wasting of money now
or in the future, unnecessary increases in user disturbances now or in
the future or, even worse, unnecessary increases in the number of
accidents that may happen.
Steps
In order for engineers to be able to communicate their concerns –
for example, with respect to risk, reliability, availability and
safety – to managers in a way that they can understand, engineers
need to realise what is important to managers. Managers are not
interested in the technical aspects. They operate at the system
level and are concerned with how their infrastructure is going to
function as a whole and how the infrastructure is going to provide
service. They are interested only in taking action to fix a technical
issue if they feel that how their infrastructure functions as a whole
is in jeopardy and the costs of doing so are justified. This means
that the engineers have to be able to show that the state of the
infrastructure leads to negative impacts on, or costs to, the
stakeholders. As managers are concerned with not only right
now, but also the future, engineers must be aware that they have
to be sure to convey to managers that they know, and have
modelled well, not only how the entire system functions now but
also how it functions in the future. As one cannot, of course,
model everything, the engineer, when communicating with
managers, needs to be sure that they cover all aspects that are of
concern to the managers and models the differences of what will
happen when the engineer’s advice is followed and when not.
Additionally, engineers must ensure that when it comes to
displaying the results of their simulations that they focus on the
things that matter to managers at the right level and not on the
things that are important to the engineer. Of course, the models
that are used for communication do not replace the ones required
by the engineers to propose very specific answers to specific
problems, but are rather built on top of, or in conjunction to, these
models. The four basic steps to ensure that engineers can speak to
managers are described in the next four subsections, using a
fictive but realistic railway network (Figure 1), where it is hoped
to determine how much money is to be spent on maintenance.
The network consists of 86 bridges with a total deck surface area
of 20 076 m
2
, 73 track sections measuring a total of 211 242 m
length, 66 earthworks measuring a total of 360 261 m
3
and 130
switches. The numbers of trains per day on each of the 11 links
are given in Table 6, and each carry on average 100 passengers.
In order to conduct the example, a relatively common methodology
and relatively common techniques are used. As the goal of the
paper is to explain an approach that can be used by engineers to
communicate in terms of service to the manager, the details of the
used methodology and tools are intentionally omitted. This
omission helps to keep focus on the goal of the paper and avoids
giving the impression that the authors are suggesting the use of a
specific methodology or specific techniques.
Provide a complete description of the infrastructure
(step 1)
The first step is to provide a complete description of the
infrastructure to be included in the analysis – complete, but not
necessarily deep, or only as deep as necessary. For example, an
infrastructure manager needs to know that all objects that are
required to provide the required service are included in the
evaluation – for example, all earthworks, all tracks, all bridges
and all switches – but it is not necessary for them to know that
each beam in steel bridge number 10 is modelled exactly. It is
also not of much use to them if someone is conducting an
evaluation with just bridges, even if modelled in lots of detail.
The most they will get out of such an analysis is a prioritisation
of which bridges should have an intervention in the next planning
Table 5. Examples of cost–benefit analysis in infrastructure decision making
Reference Costs and benefits Decision made
A further improvement would
be to quantify …
Peng (2011), Peng
and Ouyang (2014)
Costs of intervention, costs of network
operation
How to group
interventions on
tracks
Accident costs
Zhao et al. (2006) Costs of intervention Ballast tamping
intervention
strategy
Accident and travel time costs
Budai-Balke (2009) Costs of intervention Track intervention
strategy
Accident cost
Thoft-Christensen
(2009)
Costs of intervention Bridge intervention
strategy
Accident cost
Zhang et al. (2013) Costs of intervention, safety, travel disruption Track intervention
strategy
Travel time costs
Lyngby et al. (2008) Cost of intervention, cost of failure (i.e. cost of
unavailability of service due to failure)
Interventions to be
executed on tracks
Risks related to accidents, costs for traffic
interruption due to preventive interventions
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