RAIB Investigation Report: Failure In Civil Engineering Infrastructure Essay.

Task 1. Review the failure reports on the Rail Accident Investigation . Identify up to three failures that are related in some way to a failure of the civil engineering infrastructure, for example the track, the track foundation, the earthworks around a railway or structures linked to the railway.

Task 2. Thoroughly read and evaluate the whole of the RAIB report for your selected failure and develop an understanding of the reasons for the failure in civil engineering terms. This will require you to draw on a wide range of knowledge and understanding you have acquired already on the BEng Civil and Environmental Engineering course, for example including structures, geotechnics, materials, hydraulics as well as transport engineering.

Task 3. Provide a succinct report. Your report will include an introduction which states why you have selected the case study, in contrast to the other two possible case study candidates you identified. The report should summarise and evaluate the RAIB report. You should describe the failure location, the mechanism of the failure in engineering terms, and the findings of the RAIB report. You should prepare and develop your own appropriately annotated and dimensioned hand-drawn sketches to show, as appropriate, plan, cross-section, long section, and detail. You should develop, if it is appropriate, some approximate calculations which show why the failure occurred. You must ensure that you bring your own judgements to bear, that is to say you must evaluate what you are reading in the report using the engineering knowledge and skills you have developed to date.

Title: Construction problem of RAIB investigation report

• The RAIB website (Rail Accident Investigation Branch (RAIB), 2016)contains a database for investigation reports of incidents encountered in the rail transport sector. The reports analyse specific incidences, their date of occurrence, cause of incidence and necessary mitigation steps to avoid similar incidents in future. In this report, we shall review three cases from RAIB website, the Baildon track incident as the main case study, Langworth derailment incident and structural failure at the Lamington Viaduct. The choice of case studies was determined by the following factors:

• The extent of structural failure in the rail infrastructure, tracks, surrounding earthworks and the track foundation during the time of the incident.
• Safe, effective rail and sustainable track design.
• Proper and adequate drainage network for the rail system.

The study of the three case studies mentioned above will offer insight into approaches that should be taken during the design of an efficient and safe railway network. Essential factors to be considered during the railway design include a working drainage, structurally sound rail components and infrastructure and geotechnical considerations. Structurally sound infrastructure is vital to a safe rail system, especially in the steel structures that form most of the supporting infrastructure. A majority of rail incidents can be attributed to structural failure or lack of proper oversight over the structural components. A proper culvert system should be designed and installed in the rail system to avoid cases of line closures, derailment, geotechnical instabilities, injuries and fatalities (American Society of Civil Engineers, 1993).

• The Baildon Track Incident
• The Baildon track incident occurred on 7^th June, 2016 between 1629 hrs and 1758hrs. A portion of the supporting embankment of the single line was carried away by flood water, thus one of the rails was left unsupported over a length of approximately 4 metres. None of the three passenger trains were derailed and fortunately no injuries nor fatalities were reported.
• Nearby residents initially noticed the washed out tracks and informed the Fire and Rescue service office in the vicinity. In addition, the driver of one of the rains and concerned passengers voiced their reports on the damaged track to the emergency services. However, inability of the emergency unit and railway controllers to close the line promptly after receiving the damaged track reports caused the three near miss incidents.
• A similar occurrence was reported in August 2012 at the same location and mitigation measures recommended to avoid similar incidents. However, none of the measures has been implemented. These measures include:

• Improved emergency response to safety messages and incident reports.
• Actions to reduce the risk of additional washouts at Baildon.
• Improved relay of critical safety communication between the railway staff; drivers, signallers and rail controllers.
• Continuous monitoring and maintenance of the rail to guarantee proper safety standards.

• The Structural Failure at the Lamington Viaduct
• The incident took place on the 31^st December of 2015 at 0557hrs. The Lamington viaduct experienced subsidence that caused serious track deformation when a Crewe-Glasgow passenger train at speeds of 177km/hr passed over the track. The early stages of the track defection on the viaduct were reported by one of the train drivers. However, there were no significant track defects evidenced by the technical teams deployed to investigate. Large track defections were later on reported after the resumption of train movements which led to the damage of the central pier. This specific viaduct spans the bend of a river hence the pier sides could easily be washed away since they have shallow foundations.
• A similar incident was reported earlier in 2005 and a pending recommendation scheme for a permanent scour protection of the piers had been deferred to 2016 due to essential environmental approvals. As a precautionary measure, recommendations were made in the short term and the viaduct was included on the list of bridges that were vulnerable hence placed under special watch during flooding conditions.
• The Derailment at near Langworth, Lincolnshire
• The accident took place on 30^th June 2015 at approximately 1415hrs and involved a freight train carrying 22 empty diesel fuel tank wagons. The latter wagons from the eleventh derailed after the locomotive and the first ten wagons went beyond the buckle successfully. The rail infrastructure and the train were extensively damaged. No fatalities or property damage was reported.
• The investigations carried out showed that the rail forces succumbed to forces of thermal expansion surpassing the capacity of the ballast to contain the track due to high temperatures. This day has been recorded to be the hottest day to date. An existing misalignment minimised the track’s resistance to buckling. The buckling was increased by the fast by-passing train which increased the track’s susceptibility to buckling. Figure 4 in the Appendices illustrates schematically, the cross-section showing the walkways and the main beams.

• The Baildon track incidence was chosen as the main case study for the following reasons:

• To understand the vital role of an efficient drainage system in a railway network.
• To find out the underlying fault triggers in the rail infrastructure.
• In view of the Baildon case, an effective and safe railway network should be designed with an effective and adequate drainage system. The culvert system plays a major role in rail drainage. Exclusion of these infrastructural design concepts may be the cause for line closures, geotechnical instabilities, derailment, injuries and fatalities as the worst case scenario(American Society of Civil Engineers, 1993).
• The investigation report present in RAIB website (Rail Accident Investigation Branch (RAIB), 2016) confirms that the passenger trains were in good condition. An examination of the section of the track that was washed away by flood water shows that its rails were mounted on the concrete sleepers that were placed on ballast atop clay soil. This is the section that contains the ending of the shallow cutting and the beginning of the single sided embankments as shown in Figure 3 below.
• Failure Location
• The Baildon railway is a 7.6 metres long single track line spanning from south-west to north east, between Guiseley and Shipley. The washout location was close to 630 meters south west of the railway station.

• As mentioned above, Baildon’s track incident was triggered by washing away of the ballast beneath one of thetrack’s rails over a distance of approximately 4 metres, Several factors that can be attributed to this including;
• Inability of the drainage system underneath the track to cope with large volumes of water due to flash floods.
• Large volumes of flood water along the railway line was directed to the single sided embankment.
• Following the previously experienced flood the repair could not withstand the heavy water flow.
• Basically, a couple of flooding risks are characteristic of railway culverts and these may be quantified using hydraulic/hydrologic principles, culvert capacity or even flood intensity. The major principle inputs include,
• The culvert diameter
• The culvert depth beneath the track level
• The culvert’s length, condition and
• The characteristics of the local rainfall.
• Referencing to this specific incident, the flooding of the track was mainly triggered by water overflow from inspection chambers on the two sides of the railway as shown in Figure 4 below. This water then flowed down either side onto the track. From this understanding, it was certain the drainage system must have been unable to withstand the heavy water flow due to flash floods (Anon., 2005).

Conclusion

An assessment of the rain incidents documented in the RAIB website(Rail Accident Investigation Branch (RAIB), 2016) confirm the importance of sound rail infrastructure, open and efficient communication between the users and rail staff, prompt response to emergency alarms and implementation of recommendations to avoid similar incidents. It is of utmost importance that infrastructure design should accommodate anticipated harsh weather patterns. As illustrated in the Baildon case study, the culvert system for the rail should have been designed for anticipated heavy water flow during the rainy season owing to the fact that the particular section of rail was located on a river bend. An examination of all the case studies listed in this report indicates that similar incidents had occurred at least five years before the examined incident, indicating that recommended measures were not implemented. In addition, there was delayed response to emergency alarm in all the case studies.

In conclusion, for an efficient and safe rail network, the infrastructure should be structurally sound, have regular repair and maintenance checks to establish fault triggers and have an emergency unit that responds promptly to alarms.

References

American Society of Civil Engineers, 1993. Design and construction of Urban Stormwater Management Systems. Third ed. Washington: ASCE Publications.non., 2005. Environmental Vibration: Prediction, Monitoring, Mitigation and Evaluation. Okoyama, CRC Press, pp. 20-22.

Rail Accident Investigation Branch (RAIB), 2016. Gov.uk. [Online] Available at: https://www.gov.uk/raib-reports/trains-passed-over-washed-out-track-at-baildon [Accessed 10 April 2018].ge system of the explored case study incident