Infrastructure Asset Management

Semester 2 (2022-23) Coursework Brief

Key Information

Intended Learning Outcomes

• Understanding the development of maintenance strategies for bridge infrastructure assets.
• Appreciating the difference between condition-based and performance-based models for infrastructure asset management.
• Developing basic optimisation skills for asset management planning.
• Presenting large amounts of data in an organised and efficient way.

Coursework Brief

You are part of the team responsible for the asset management of a stock of similar metallic railway bridges owned by Network Rail on one of their main Routes. Figure 1 shows a cross-section of the type of bridge, which consists of two main girders and cross-beams in-between. The dimensions of the main girders and the cross-girders are shown in Figure 2.

You are required to produce whole life maintenance planning for the next 105 years for this type of bridge using the LCAT tool provided. A number of the bridges in the route have been found to be corroded through their latest inspections and some appear to be uncorroded. On the corroded bridges the inspections have shown that there is 30% loss of flange thickness (both top and bottom) and web on both the cross-girders and main-girders.

The railway Route on which the bridges are located stretches over rural and industrial environments.

Tasks

By using the LCAT tool, analyse the following maintenance regimes for typical bridges:

• A do-minimum regime where only painting (re-coating) is applied on the bridge members (without any strengthening). Compare the whole-life costs resulting through using two different types of coatings separately, i.e. M27.4 and M21 for different element exposure levels (i.e when 10%, 50% or 90% of the element becomes exposed). Discussion should include reflection on the rate of strength loss over time and the remaining strength of the girders (in terms of % of nominal strength) at the end of the 105- year period for each case. Consider the main girders and cross-girders separately and discuss the differences in the results obtained between them. One set of analysis should be carried out for a corroded bridge and one set for an uncorroded bridge. Then, select one paint type and one type of member (i.e. main-girder or cross-girder) and compare the performance of a bridge in an industrial environment to the performance of a bridge in a

rural environment. Compare the differences in the maintenance strategies obtained from the LCAT tool for the different scenarios analysed and comment on the results obtained between the different scenarios. [40%]

• Repeat part (a) by carrying out strengthening interventions based on three different remaining relative strength limits (i.e. 99%, 95% and 90%). In this part, consider only a bridge located in an industrial environment and choose one paint type.   Observe how the relative strengths reduce over time due to deterioration and comments on the relative criticality of each (i.e. buckling strength, shear strength and bending strength). You can assume that each strengthening intervention is carried out by increasing the element thickness by 1 mm. Consider both the main girder and the cross-girders and discuss the observations between the two types of members. [30%]

• The bridge owner would like to assess the cost of keeping the bridge in excellent condition. That means not allowing any of the relative strengths (i.e. local buckling, shear and bending) reducing to more than 98% of the nominal strength. By analysing a number of difference maintenance strategies, combining re-coating (different paint types, different coverage percentages) and strengthening (different plate thicknesses in 0.5mm increments) interventions, propose an optimum intervention planning and estimate the optimum whole-life cost for it. Concentrate on the main girder only. You are not expected to carry out a full optimization; a reasonable number of different regimes you can attempt analysing is around 10-12. Discuss the results obtained from the different analyses carried out. [30%]

Data

• The discount factor can be assumed as 3.5%.
• The costs associated with the interventions are as follows:
• re-coating by using M27.4 paint system = £8,000
• re-coating by using M21 paint system = £14,000
• each 1 mm of strengthening = £26,000
• Painting requires a two-night possession with an associated cost of £50,000.
• Strengthening   requires   five-day   possession   with    an   associated   cost of

£100,000/day.

Note that the above costs should be defined as total costs in the LCAT tool. There is no need to break down the costs into labour, plant, materials, etc.

Marking Criteria

The coursework will be marked based on the following criteria:

• Good organisation of the report and clarity of presentation of material.
• Correctness of analysis, associated inputs and assumptions made.

• Understanding of the observations from the results obtained, breadth and depth of the discussion of the results.
• Completeness of analysis scenarios requested by the brief.

The percentage of marks for each question is indicated in the previous section at the end of each question description.

Clearly state any assumptions you are making in your coursework. The results should be presented in terms of whole-life costs as well as the graphs obtained from the LCAT tool in terms of coating coverage, component thickness over time as well as relative strength over time. Environmental impact costs should be neglected. It is important to include discussion of the results demonstrating an understanding of the observations.

The University grade descriptors against which the work is marked are available in  the same coursework folder. The same folder also contains the LCAT tool and its manual, which explains how it can be used. There will also be a demonstration of the use of the tool in class in one of the following weeks.

Feedback opportunities

You are welcome to ask for advice when working on your coursework if you get stuck or you need any clarifications. The best opportunities would be to ask directly during the face-to-face seminars and/or post questions on the portal  discussion forum that is specifically created for the coursework. Guidance on when you may start working on your coursework will be given during the live seminars.

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