3. Maintenance Planning

Maintenance Strategy 1 | Maintenance Strategy 2 | Maintenance Strategy 3 | Maintenance Strategy 4

Maintainace optimisation

Railways are a vital part of everyday life, providing essential connections for commuters and long-distance travellers. Effective maintenance planning is therefore crucial to minimise service disruptions and ensure reliable passenger access. Unlike many other types of systems, railway stations measure serviceability not by full system availability, but by maximising the time during which at least one track remains operational. Maintaining partial functionality allows services to continue even during maintenance activities, reducing inconvenience for users.

This project explores four integrated maintenance strategies designed to improve infrastructure performance over the long term. The main objectives are to reduce passenger disruption and enhance overall system reliability. By coordinating maintenance activities across different systems, the project aims to ensure that critical components are serviced efficiently and at appropriate intervals.

Through strategic planning and optimisation, these approaches also seek to lower long-term operational and maintenance costs. By aligning technical performance with user needs, the project demonstrates how carefully designed maintenance strategies can contribute to a more resilient, sustainable, and user-focused railway network.

Lifespan and operation

The total lifespan of the integrated railway station system is set at 120 years. This duration is modelled after Hamburg Central Station, which opened in 1906 and remains one of Germany’s oldest operational railway hubs. This historical precedent provides a realistic benchmark for the service life of major transit infrastructure. Similar to the Berlin S-Bahn and other international metropolitan networks, it is assumed that the station remains accessible, but specific tracks may be shut overnight during weekdays. This operational window allows many maintenance activities to be conducted during the night shift with zero impact on daytime service availability. Only maintenance activities with a duration above 0 days will be considered in this study.

Pre-optimised timelines

The pre-optimised standard frequencies of the maintenance interventions shown in Table 1 were used to create initial maintenance timelines for each system (Figures1-6). These baselines represent the current approach before maintenance strategies were applied,

The upper and lower range frequencies define the admissible window for each intervention. These ranges serve as constraints for the optimisation used in Strategies 1 to 4, allowing the model to shift maintenance dates to achieve the best balance among cost, environmental impact, and station downtime.

SystemsEventCodeInterventionLower Range Frequency (years)Upper Range Frequency (years)Standard Frequency (years)Duration (days)
Precast Concrete Facade [1]CR.pcfCoating Refresh1218153
JM.pcfJoint Maintenance1525205
PR.pcfPanel Replacement40606010
Glass Curtain WallDC.gcwdeep cleaning [6]51073
GR.gcwgasket replacement [5]814105
IR.gcwIGU replacement [4]40604014
Steel Truss BridgeMP.stbMember Replacement1020157
FR.stbFull Recoating20302521
Building ReinforcedSR.brcsSpall Repair5706021
CS/JR.brcsCrack Sealing / Joints Refurbishment2030257
CT.brcpCarbonation Treatment1525205
SG.brcfStructural Grounding30504041
Railway Track Concrete sleepersSSRC.rlw_slpSystematic sleeper renewal campaign406050  [7]5
FRR.rlw_rlsFull Rail Renewal6010080 [8]1.25
Railway Track Timber sleepersrlwt_TS.fullFull sleeper renewal1530 20 [2]1
rlwt_SB.geoGeotextile full replacement80120 100 [3]14
FRR.rlwtFull Rail Renewal60100 801.25
Table 1 – Initial Maintenance Frequencies and Admissible Ranges
Figure 1 – 120-Year Timeline Railway Concrete Sleeper
Figure 2 – 120-year Timeline Railway Timber Sleeper
Figure 3 – 120-year Timeline Precast Concrete Façade
Figure 4 – 120 Year Timeline Glass Curtain Wall
Figure 5 – 120 Year Timeline Steel Truss Bridge
Figure 6 – 120 Year Timeline Station Building

Maintainance strategies

Strategy 1- Railway Asynchronous Maintenance

Goal

To allow continued service to the station while maintenance is carried out, only one line of track is closed at any given time. This enables the implementation of single-line working, ensuring that rail operations can continue while maintenance activities are undertaken on the adjacent track.

Approach

The two railways (timber sleeper and concrete sleeper)are treated as independent systems;  they will have their maintenance work scheduled at different times wherever possible. The selection of the railway maintenance schedule was driven by filtering for solutions that contained no overlapping intersystem maintenance events. Conversely, intrasystem maintenance events were optimised for overlap to reduce the total closure duration for each specific track.

Figure 7 – Total interruptions duration (days) of Two Railway Systems (before optimisation)

The original maintenance strategy has 6 different intervention types and in total 23.5 days of interruptions for a total lifetime of 120 years. This interruption duration is calculated with the standard frequencies.

SystemsEventCodeInterventionLower Range Frequency (years)Upper Range Frequency (years)Duration (days)
Railway Track Concrete sleepersSSRC.rlw_slpSystematic sleeper renewal campaign40605
RM.rlw_rlsRail milling250
FRR.rlw_rlsFull Rail Renewal601001.25
Railway Track Timber sleepersrlwt_TS.fullFull sleeper renewal15301
rlwt_SB.geoGeotextile full replacement8012014
FRR.rlwtFull Rail Renewal601001.25
Table 2 – Inputs of Design Exploration for Two Railway Systems
Figure 8 – Design exploration of Two Railway Systems
Figure 9 – Design exploration of Two Railway Systems

This figure shows the design exploration results used to identify maintenance timelines where the two railway systems do not overlap.
Each point represents a possible combination of maintenance timing between the two railway systems.

The selected point indicates the solution where maintenance events are fully separated in time, ensuring that both railway tracks are never closed simultaneously.

Figure 10 – Maintenance Schedule for Two Railway Systems (after optimisation)

This table shows the optimised maintenance schedule candidates for the two railway systems.All selected solutions have an overlap count of 0, meaning that maintenance events between the two railway systems do not occur at the same time.This table shows the optimised maintenance schedule candidates for the two railway systems.All selected solutions have an overlap count of 0, meaning that maintenance events between the two railway systems do not occur at the same time.

SystemsEventCodeInterventionLower Range of Best Frequency (years)Upper Rangeof Best Frequency (years)Total Duration (days)
Railway Track Concrete sleepersSSRC.rlw_slpSystematic sleeper renewal campaign515128.5
FRR.rlw_rlsFull Rail Renewal8080
Railway Track Timber sleepersrlwt_TS.fullFull sleeper renewal3030
rlwt_SB.geoGeotextile full replacement9090
FRR.rlwtFull Rail Renewal6566
Table 3 – Maintenance Schedule for Two Railway Systems (after optimisation)

The total maintenance duration was originally 23.25 days, but after applying the optimisation constraints (zero overlap and minimum gap requirements), the final selected duration increased to 28.5 days.

Strategy 2- Railways Grouped with the Nearest System

Goal

The objective of this strategy is to facilitate single-track working by grouping each railway track with its respective passenger access system. This ensures that maintenance activities affecting both access and track operations are coordinated and executed simultaneously. By aligning these interventions, the station avoids redundant closures, while the staggered scheduling derived in Strategy 1 ensures that the adjacent track remains operational.

Approach

The maintenance schedules established in Strategy 1 serve as the foundation for this approach, maintaining the requirement that the two tracks are serviced at different times. Each railway system is paired with the specific infrastructure that provides its access: the timber sleeper track is grouped with the steel truss bridge, and the concrete sleeper track is grouped with the station building.

For the timber railway and concrete railway components, the frequencies used are the “Best Frequency” results obtained from the initial Strategy 1 optimisation. Conversely, the frequencies for the steel truss bridge and the reinforced concrete building are taken directly from original maintenance data without additional optimisation. This allows for a clear evaluation of how existing structural maintenance needs integrate with optimised railway schedules.

Strategy 2-1  Railway Track Timber sleepers and Steel Truss Bridge

Because the timber sleeper track is reached exclusively via the footbridge, coupling bridge maintenance with timber railway interventions prevents the track from being inaccessible by a bridge closure. Before optimisation, this combined grouping accounted for 129.25 days of interruptions over the 120-year lifecycle. Following the alignment of bridge member replacement and recoating with the track’s best frequencies, the total duration is significantly reduced.

Figure 11 – Total duration (days) of Railway Track Timber sleepers and Steel Truss Bridge (before optimisation)

The original maintenance strategy has 5 different intervention types and in total 129.25 days of interruptions for a total lifetime of 120 years. This interruption duration is calculated with the standard frequencies.

SystemsEventCodeInterventionLower Rangeof Best Frequency (years)Upper Range  of Best Frequency (years)Duration (days)
Railway Track Timber sleepersrlwt_TS.fullFull sleeper renewal30301
rlwt_SB.geoGeotextile full replacement909014
FRR.rlwtFull Rail Renewal65661.25
SystemsEventCodeInterventionLower Range Frequency (years)Upper Range Frequency (years)Duration (days)
Steel Truss BridgeMP.stbMember Replacement10207
FR.stbFull Recoating203021
Table 4 – Inputs of Design Exploration for Railway Track Timber sleepers(after optimization) and Steel Truss Bridge (before optimisation)
Figure 12: Design Exploration of Railway Track Timber Sleeper and Steel Truss Bridge
Figure 13 – Design Exploration of Railway Track Timber Sleeper and Steel Truss Bridge

This table presents the optimised maintenance schedule for the timber sleeper railway system and the steel truss bridge. The selected schedule represents the minimum feasible maintenance duration of 66.25 days, as the optimisation prioritises minimising total downtime rather than maximising the maintenance gap.

SystemsEventCodeInterventionBest Frequency (years)Total Duration (days)
Railway Track Timber sleepersrlwt_TS.fullFull sleeper renewal3066.25
rlwt_SB.geoGeotextile full replacement90
FRR.rlwtFull Rail Renewal66
Steel Truss BridgeMP.stbMember Replacement20
FR.stbFull Recoating20
Table 5 – Maintenance Schedule for Railway Track Timber sleepers and Steel Truss Bridge (after optimisation)

The total maintenance duration was originally 129.25 days, but after applying the optimisation constraints,  the final selected duration decreased to 66.25 days.

Strategy 2-2  Railway Track Concrete sleepers and Building Reinforced

The concrete sleeper track is accessed directly through the station building. Consequently, building maintenance is coupled with the concrete railway’s optimised maintenance cycle. Originally, this strategy involved 7 different intervention types totalling 138 days of interruptions. By synchronising these structural tasks with the primary rail renewals, the downtime is consolidated into fewer, more efficient operational windows.

Figure 14 – Total duration (days) of Railway Track Concrete sleepers and Building Reinforced (before optimisation)

The original maintenance strategy has 7 different intervention types and in total 138 days of interruptions for a total lifetime of 120 years. This interruption duration is calculated with the standard frequencies.

Strategy 3- Grouped Façade Maintenance

Goal

To reduce on-site manpower requirements and overall maintenance costs by coordinating both façade systems, recognising that façade maintenance does not require closure of the station building and does not interrupt railway operations. By grouping façade interventions, the number of times contractors need to come to the site is reduced, which should lower overall maintenance costs. This strategy therefore focuses on minimising repeated access requirements and user disruption, rather than maintaining system availability, since façade maintenance does not cause system disruption.

Approach

The two façade systems are treated as a single maintenance group, and their interventions are scheduled concurrently wherever possible. 

Figure 15 – Total duration (days) of Two Facade Systems (before optimisation)

The original second maintenance strategy has 6 different intervention types and in total 135 days of interruptions for a total lifetime of 120 years. This interruption duration is calculated with the standard frequencies.

SystemsEventCodeInterventionLower Range Frequency (years)Upper Range Frequency (years)Duration (days)
Precast Concrete FacadeCR.pcfCoating Refresh12183
JM.pcfJoint Maintenance15255
PR.pcfPanel Replacement406010
Glass Curtain WallDC.gcwdeep cleaning5103
GR.gcwgasket replacement8145
IR.gcwIGU replacement406014
Table 6 – Inputs of Design Exploration for Two Facade Systems (before optimisation)
Figure 16 – Design Exploration of Two Facade Systems
Figure 17 – Design Exploration of Two Facade Systems

This table presents the optimised maintenance schedule for the Two Facade Systems. The selected schedule represents the minimum feasible maintenance duration of 53 days, as the optimisation prioritises minimising total downtime rather than maximising the maintenance gap.

SystemsEventCodeInterventionBest  Frequency (years)Total Duration (days)
Precast Concrete FacadeCR.pcfCoating Refresh1853
JM.pcfJoint Maintenance18
PR.pcfPanel Replacement60
Glass Curtain WallDC.gcwdeep cleaning9
GR.gcwgasket replacement9
IR.gcwIGU replacement60
Table 7 – Maintenance Schedule for Two Facade Systems (after optimisation)

The total maintenance duration was originally 135 days, but after applying the optimisation constraints,  the final selected duration decreased to 53 days.

Strategy 4- Bridge and Building Grouped

Goal

Similar to the grouping of the façades, an alternative maintenance strategy is to coordinate the maintenance of both the bridge and the station building. By grouping these activities, the total system shutdown time can be reduced, because when both systems are closed, the entire station must close due to a lack of access to the rail. This approach also reduces cost, as the contractors required for bridge and building maintenance are likely similar, meaning the number of site call-outs can be reduced.

Approach

Bridge and building maintenance activities are scheduled together within a shared maintenance timeline.

Figure 18 – Total duration (days) of Steel Truss Bridge and Building Reinforced (before optimisation)

The original second maintenance strategy has 6 different intervention types and in total 295 days of interruptions for a total lifetime of 120 years. This interruption duration is calculated with the standard frequencies.

SystemsEventCodeInterventionLower Range Frequency (years)Upper Range Frequency (years)Duration (days)
Steel Truss BridgeMP.stbMember Replacement10207
FR.stbFull Recoating203021
Building ReinforcedSR.brcsSpall Repair57021
CS/JR.brcsCrack Sealing / Joints Refurbishment20307
CT.brcpCarbonation Treatment15255
SG.brcfStructural Grounding305041
Table 8 – Inputs of Design Exploration for Steel Truss Bridge and Building Reinforced (before optimisation)
Figure 19 – Design Exploration of Steel Truss Bridge and Building Reinforced 
Figure 20 – Design Exploration of Steel Truss Bridge and Building Reinforced 

This table presents the optimised maintenance schedule for the Steel Truss Bridge and Building Reinforced. The selected schedule represents the minimum feasible maintenance duration of 172 days, as the optimisation prioritises minimising total downtime rather than maximising the maintenance gap.

SystemsEventCodeInterventionBest  Frequency (years)Total Duration (days)
Steel Truss BridgeMP.stbMember Replacement20172
FR.stbFull Recoating20
Building ReinforcedSR.brcsSpall Repair50
CS/JR.brcsCrack Sealing / Joints Refurbishment20
CT.brcpCarbonation Treatment20
SG.brcfStructural Grounding40
Table 9 – Maintenance Schedule for Steel Truss Bridge and Building Reinforced (after optimisation)

The total maintenance duration was originally 295 days, but after applying the optimisation constraints,  the final selected duration decreased to 172 days.

However, This strategy was not adopted in the final maintenance plan. Although these systems show positive relationships, it is weaker and less operationally critical compared to the railway access system relationships defined in Strategy 2. This strategy did not provide sufficient benefit to justify the potential risks to system downtime.

Best Timeline

SystemsEventCodeInterventionBest  Frequency (years)
Precast Concrete FacadeCR.pcfCoating Refresh18
JM.pcfJoint Maintenance18
PR.pcfPanel Replacement60
Glass Curtain WallDC.gcwdeep cleaning9
GR.gcwgasket replacement9
IR.gcwIGU replacement60
Steel Truss BridgeMP.stbMember Replacement20
FR.stbFull Recoating20
Building ReinforcedSR.brcsSpall Repair50
CS/JR.brcsCrack Sealing / Joints Refurbishment20
CT.brcpCarbonation Treatment20
SG.brcfStructural Grounding40
Railway Track Concrete sleepersSSRC.rlw_slpSystematic sleeper renewal campaign51
RM.rlw_rlsRail milling5
FRR.rlw_rlsFull Rail Renewal80
Railway Track Timber sleepersrlwt_TS.fullFull sleeper renewal30
rlwt_SB.geoGeotextile full replacement90
FRR.rlwtFull Rail Renewal66
Table 10 – Best Timeline

Conclusion

By evaluating the four proposed maintenance strategies against the 120 year lifecycle of the station, a final Best Timeline has been developed. This integrated approach combines the strengths of Strategies 1, 2, and 3, while intentionally omitting Strategy 4. The integrated maintenance timeline was developed based on system relationships and operational constraints.

The two railway systems are scheduled to avoid overlapping maintenance periods, while maintenance events within each individual railway system are aligned where possible. This approach minimises downtime at the system level while ensuring that both railway tracks are not closed simultaneously, thereby maintaining overall system availability. While the staggering of events ensures the station remains functional, it naturally extends the cumulative duration of individual track closures over the lifecycle. This result demonstrates that to maintain the seven day railway objective, a slight increase in total work days is a necessary trade off to ensure that passengers always have access to at least one operational railway.

The optimised railway timelines were aligned, where feasible, with systems that have positive relationships. This includes coordinating the timber railway with the bridge system and the concrete railway with the building system. This alignment maximises simultaneous maintenance opportunities and reduces the frequency of access-related shutdowns.

Both façade systems were scheduled to overlap with each other. As façade maintenance has no direct operational dependency on railway or access systems, these interventions were grouped independently. This reduces repeated site access and maintenance effort without impacting the operational status of the rail network.

The strategy of grouping the building and bridge systems together was not adopted. Although these systems show some positive relationships, it is weaker and less operationally critical compared to the railway access system relationships defined in Strategy 2. This grouping did not provide sufficient benefit to justify the potential risks to system downtime.

During the analysis, only positive and negative relationships were used to define scheduling constraints. Positive relationships allow for simultaneous maintenance, while negative relationships require temporal separation. Except for the dual railway constraint, all other integrations aim to minimise overall downtime by coordinating compatible maintenance events.

[1] Jasiczak, W., & Girus, I. (2017). Defect frequencies in Polish precast concrete façades.
[2] Network Rail. “Our High Output team delivers rapid renewals.” Link. Accessed 21 12 2025.
[3] Terram Geosynthetics Ltd. “Extending track bed life using geosynthetics.” Link. Accessed 22 12 2025.
[4] K. P. Allana, Curtain Wall Handbook, 2017.
[5] E. T. Yalaz, Curtain Wall Deficiency and Failures: Observations on Multi-Story Buildings in Istanbul, 2016.
[6] Environmental Protection Administration (EPA), Acid Rain and Air Pollution Annual Report.
[7] https://extranet.artc.com.au/docs/eng/track-civil/procedures/sf/Section2.pdf?26
[8] https://ipweelearning.org.in/images/PDF/Sem_2/Sem_2_2_Track_Renewal.pdf
Home | 1. Introduction | 2. Integration Context | 3. Maintenance Planning | 4. Life-Cycle Analysis | 5. Objective Optimization | 6. Conclusion