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Systems thinking, Site operations, and Health and Safety – Civil Engineering – Construction Costing and Contracts – Year 2 – Project Rise

Disclaimer: This work has been submitted by a student. Any opinions, findings, conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of Project Rise

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Introduction

The aim of this report is to investigate systems thinking and use it to analyse the nature of work for an elevated water construction and also to implement essential systems to guarantee quality of work to the client as well as provide safe working conditions to employees working for this construction company

1.0. Systems’ thinking

Systems’ thinking is defined as an approach to problem solving by viewing “problems” as parts of an overall system rather than reacting to specific part, outcomes or events. One of the best ways of solving problems using systems’ thinking is to model a problematic scenario into simple input-output system. The input-output system consists of;

  • Input – things to be converted by the conversion process
  • Output – things produced or created as a result of the conversion process
  • Constraints – elements that limit the conversion process
  • Opportunities – sub product of conversion process which benefits another process
  • Mechanisms – personnel, equipment and technology used in conversion process
  • Conversion process- is an activity which uses a mechanism to convert an input into an output under certain constraints while offering opportunities for other conversion process.
Figure 1 – Input-Output Model

Setting out

This is the construction process by which the specific locations of structures to be constructed are located in the site. The input of this process is the bare land and the output will be the location of the structural elements to be constructed such as columns. The mechanisms used in this process are skills of surveyors and surveying equipment. The main constraints of this process are the difficulty to locate points due to possible weather conditions and uneven topology of the construction site.

Construction of the base

This is the construction process by which the foundation for the water tank is constructed. The inputs for this process are the bare lands with marking of perimeter of foundation and construction materials. The outputs will be the foundation of the water tank. The mechanisms used in the process are the skills of labour, excavating machinery, steel bar bending machines and concrete mixer. The main constraints will be unforeseeable adverse weather conditions and unexpected ground conditions and the opportunities are the fact that the workshop setup to make concrete and to bend reinforcement steel can be used for other construction process like construction of columns and beams.

Construction of columns and beams

This is the construction process by which columns and beams for the water tank is constructed. The inputs for this process are construction materials and formwork and the output is the columns and beams of the water tank. The mechanisms used in the process are the skilled labour, steel bending machines and concrete mixer. The constraints are unexpected adverse weather conditions and the fact that there are many mistakes that can be made in the dimensions of structures and when mixing of concrete.

Curing

This is the process by which the concrete is protected from loss of moisture and kept within a reasonable temperature range so that the concrete can reach it complete strength. The inputs for this process are water and concrete and the output is fully cured concrete structure. The mechanisms used in the process are the curing techniques like ponding and spraying. The constraints are the fact that hot weather can decrease moisture content of concrete due to evaporation.

Environmental Protection

 This is the process by which harm caused to the surrounding environment due to the construction process is reduced to appropriate levels or eliminated altogether. Input for this process is the surrounding environment and the output is the surrounding environment with minimum change due to the construction. The mechanisms used are environmental protection techniques such as recycling waste materials and proper disposal of construction waste. The constraints are the extra costs that occur for proper environmental protection and this can delay construction too. Opportunities are the fact that cleaner environment paves way for a more sustainable future and recycling construction waste can reduce the overall cost of construction.

2.0. Systems to control the appropriate level of strength and accuracy of concrete

During the construction process there are three main places where the strength and the accuracy of the concrete is decided; during manufacturing of cement and admixtures, during mixing of concrete and during curing of concrete.

  • Manufacturing of cement and admixtures is not a part of the actual construction process therefore there is a possibility that the materials bought is of low quality.
  • The construction process is fairly large hence it requires many batches of concrete with different composition of aggregates and admixtures which can lead to mistakes in mixing of concrete which in turn can affect the strength of the concrete.
  • After the laying of the concrete its moisture level must be controlled to make sure the concrete reaches its maximum strength. If the moisture level is not properly controlled the concrete strength will reduces and form cracks and also its permeability will increase which can affect the long-term strength of reinforced concrete structures

Different concrete testing methods and  quality control mechanisms can be used in a systematic way to ensure that appropriate levels of strength and accuracy of concrete is achieved at each stage of construction. The system of quality control can be made chronologically and using feedback loops so that mistakes at each level can be detected and rectified.

  • Cube test – this is used before construction to find the compressive strength of concrete. This has to be performed 7 days before construction using the cement bought for concreting. This should be carried according to BS EN 12390-1:2012. This is used to check if bought materials is of good quality
  • Slump test – this is used to test the workability and stability of concrete and to ensure uniformity between different batches of similar concrete. This should be carried out according to BS EN 12350-2:2009
  • Windsor probe test – this is a penetration test used to find the strength of concrete after construction. This should be carried according to BS 1881-207:1992. This is to check if final structure has concrete with required strength.
  • Concrete curing – ponding and regular spraying of water are methods of concrete curing which is used to make sure concrete is cured properly

Figure 2 – System for quality control of cement

By following the above procedure it is possible to control the quality control system to achieve appropriate level of strength and accuracy of concrete. The company must appoint a qualified technical officer to be in charge of each test so that chances of error in the tests can be minimized

3.0. Health and Safety hazards

During the construction process the workers are exposed to many health and safety hazards therefore there is significant need for a safe work system to identify and to reduce the risk to an acceptable level or to eliminate it altogether. Below are some of the possible health and safety hazards pertaining to this construction process and their Risk rating;

Table 1 – Impact assessment
Impactmagnitude   
No injuries1
Negligible injuries2
Minor injuries3
Major injuries4
Single fatality5
Multiple fatalities6
Table 2 – Risk likelihood assessment  
      Likelihoodmagnitude
Within the bounds of possibility1
A rare occurrence2
Not very likely3
A 50% chance4
Very likely5
Expected6
Table 3 – Risk Assessments  
HazardImpactLikelihoodRisk rating
Falling objects from above4416
Collapse of form work or false work4416
Excavation collapse5315
Trips and falls                                        3412
Electric shocks5210
Injuries from hand tools339
Exposure to hazardous chemicals414
Exposure to high vibration133
Inhalation of dust133

Risk rating = Impact x Likelihood of risk

Risk assessment is the determination of quantitative or qualitative value of risk related to an existing situation and a recognized hazard. A risk assessment involves identifying the hazards present in any undertaking and then evaluating the extent of the risks involved while taking into account existing precautions

According to ICTAD Conditions of Contract major contracts clause 17.1 and clause 17.2 the contractor is responsible for any injury or sickness of any person whatsoever arising out of or in the course of the construction process. The possible hazards, the construction stage likely to occur in and their prevention methods are listed below;

Table 4 – Risk prevention methods

HazardsConstruction stagePrevention methods
Falling objects from aboveDuring construction of superstructurePrevented by wearing hard hats and steel toe boots
Collapse of formwork and falseworkLikely in all stages of constructionA competent engineer with adequate training and experience in designing false work and form work should be appointed.
Excavation collapseDuring excavation for baseVehicles and heavy machinery shouldn’t be kept near the excavation. Fix retaining walls during deep excavation.
Trips and fallsLikely in all stages of constructionCan be prevented by labeling  trenches, pits or any other surface that can cause workers and to slip or trip
Electric shocksLikely in all stages of constructionAvoid using electrical equipment in damp conditions unless they are specially designed for those conditions. make sure that the wires of equipment are not damaged
Injuries from hand toolsLikely in all stages of constructionPrevented by making sure the worker has enough training to use the tool and by making sure the tool is maintained properly and is in mint condition.
Exposure to hazardous chemicals (e.g. Cement and admixtures)Likely in all stages of constructionIf skin contact with these substances is inevitable, suitable protective clothing and gloves should be worn. Washing of hands after work and skin care are essential to prevent dermatitis. However, solvents should never be used to clean hands or other body parts
Exposure to high vibrationMost likely during excavation for baseWhere possible, low vibration tools should be used. They should also be properly maintained so that they are balanced and have no loose parts. Wearing anti-vibration gloves can also reduce the harmful effect of vibration.
Inhalation of dustLikely in all stages of constructionBy the use of dustproof masks.

It is the responsibility of the contractor to employ a health and safety representative who will look into the hazards pertaining this construction and implement suitable prevention method. Also according to ICTAD Conditions of contract major contracts clause 18.3, the contractor is responsible for insuring all personnel against injury.

By following the ICTAD condition and by implementing suitable prevention methods for each health and safety hazard it is possible to create a proper safe work system so that the risks can be reduced to an appropriate level or eliminated altogether.

Reference

  1. Maylor, H. (2009) Project Management. 6th edition. UK: Pearson Education
  2. Biren, P. (2000) Advances in concurrent engineering. 6th edition. USA: CRC press
  3. BSI (2012) BS EN 12390-1:2012, Testing hardened concrete. Shape, dimensions and other requirements for specimens and moulds. British Standards Online, British Standards Institution [Online] http://shop.bsigroup.com/ProductDetail/?pid=000000000030254400 [Accessed: 15th November 2014].
  4. BSI (2009) BS EN 12350-2:2009, Testing fresh concrete. Slump-test. British Standards Online, British Standards Institution [Online] http://shop.bsigroup.com/ProductDetail/?pid=000000000030164882 [Accessed: 15th November 2014].
  5. Compressive strength of concrete cubes, Available from: http://theconstructor.org/concrete/compressive-strength-of-concrete-cubes/1561/  [Accessed on 15th November, 2014]
  6. Concrete cube test explained, Available from: http://www.testcreteconcretetesting.co.uk/construction-tests-services/concrete-testing/concrete-cube-tests/ [Accessed on 11th November, 2014]
  7. The link between concrete sustainability and curing, Available from : http://www.cement.org/cement-concrete-basics/working-with-concrete/curing [Accessed on 8th November, 2014]
  8. Concrete Curing, Available from: http://www.concretenetwork.com/curing-concrete/ [Accessed on 5th November, 2014]
  9. Curing of concrete techniques, Available from: http://www.holcim.com.au/products-and-services/tools-faqs-and-resources/do-it-yourself-diy/curing-of-concrete-techniques.html[Accessed on 5th November, 2014]
  10. Workability of fresh concrete by slump test, Available from : http://www.engineeringcivil.com/workability-of-fresh-concrete-by-slump-test.html [Accessed on 8th November, 2014]
  11. Slump test, Available from: http://www.concrete.org.uk/fingertips_nuggets.asp?cmd=display&id=559 [Accessed on 8th November, 2014]
  12. Safety guide for interlocking of sheet piles, Available from: http://www.labour.gov.hk/eng/public/os/D/SheetPile.pdf [Accessed on 13th November, 2014]
  13. Foundation Work, Available from: http://www.safetypartnering.com/smd/inside_c4_e.htm [Accessed on 13th November, 2014]
  14. Sheet piling risks, Available from: http://www.marpal.co.uk/wordpress/?p=60 [Accessed on 14th November, 2014]
  15. Health and safety in construction, Available from : http://www.hse.gov.uk/construction/cdm/contractors.htm [Accessed on 14th November, 2014]

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