Table of Contents
Builder Balfour Beatty was fined S £1.2m for the collapse of a tunnel at Heathrow Airport; many lives were put at risk and hundreds of flights canceled. This occurred in the early hours of October 21, 2012. Luckily, there was no person in the tunnel at that time. When this case was presented in court, the court was told that the incidence could have crushed people to death using the nearby Piccadilly tube line. Justice Peter Cresswell, the judge handling the case reiterated that it was luck more than a judgment that people were not crushed to death.
Martin Thurgood, a representative of Health and Safety Executive, spoke to BBC arguing that such level of fine sends a clear warning to the industry, regardless of being the contractor, the client’s designers or sub-contractors and that they should take full account of workers and public safety in the course of their operations. Balfour Beatty is a corporation based in Edinburgh and is among UK’s largest building organizations. Being parts of the engineering group BICC, it was unethical for them not to observe the safety aspects of tunnel engineering before beginning the tunnel building process. The collapse of the tunnel delayed the opening of the Heathrow Express for almost six months and leads to long hold ups on the section of the Jubilee line extension, where engineers were applying similar building techniques.
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Causes of collapse
Heathrow international airport is an extremely busy airport with multiple incoming and outgoing aircraft every hour. With this comes a lot of disturbance that is transmitted to the ground. A tunnel below a runway is a mistake especially given when all other structural strength factor is kept constant. Vibrations from the movement on the airport resulted to cracking along the tunnel walls which eventually resulted in collapsing.
The engineering disaster formed a huge crater between the airport’s two main runways. Car parks and buildings were also damaged; it took several months to clear up the damage. The collapse happened while constructing a tunnel belonging to Heathrow Express Rail Link. Builder Balfour Beatty has pleaded guilty for failing to ensure that both the members of the public and its employees were safe, Geoconsult; an Austrian engineering firm , mandated for monitoring the progress of the Heathrow Express Link, also got a fine of £500,000.
According to Justice Cress, this was one of the most terrible civil engineering disasters in the history of the United Kingdom during the last quarter of a century. The Heathrow tunnels were being constructed below part of the world’s busiest airport, and in essence, there was the considerable possibility of failure. Both firms were proven guilty of falling to observe significant and appropriate standards as well as reasonable steps, leading to serious breaches of the Health and Safety Statutes.
The cause synthesis of sophisticated soft terrain collapse and the consequently reasonable solutions, ascertaining the safety of personnel and the environment preservation during tunneling are the key concerns in civil and environment projects. Associated with the nature of the operations going on in the environment, soft terrain, collapse in the tunnel, after the cause examination and environmental and geological experts researching together, the effective and reasonable interventions have been taken; and the efficiency of prevention has been validated by the mechanism of three-dimensional deformation determination using non-contact total station and the finite element numerical synthesis (Journal of the China Railway Society, 2014, p. 96)
This research reveals that the major causes are the groundwater erosion, a poor geological parameter regarding the poor discrimination of geological environment among others. the key points to reduce collapsing are; that the perfect explanation of tunnel face, timely analysis and the assessment of the geological condition at the locality of tunnel face, ascertaining sensitive and precise judgment of the surrounding rock classification and the meeting of strength requirement of supporting frameworks. And this should have been the appropriate way that could have strengthened supporting in collapse impacting region.
In addition, predicting the conditions of the surrounding rock or concrete form of collapsed body and using it to enhance the supporting strength in areas that could potentially collapse and have it done on time. After the treatments, the eventual arch crown vertical displacement of surrounding condition and primary support in the pre-collapsed area should about 17.8mm. The safety factor of the primary support structure at the side walls should be about 3.1. In conclusion, every statement must be safe and effective, authentic, providing the reference for a similar tunnel design and construction that can last for over a century (Journal of the China Railway Society, 2014, p. 96). Otherwise, constructing tunnel away from the airport could have been the best way to prevent this collapse.
- JTJ042-94 Technical specification for construction of highway tunnel. Beijing: China Communications Press, 2012.
- Y.A.N.G. Hui-jun, WANG Meng-Shu. Analysis of construction factors of surrounding rock deformation in tunneling works Journal of the China Railway Society, volume 92, 2014, p. 96 .View Record in Scopus
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