For any structure to be safe and stable, stay upright, and withstand all environmental forces, it needs attention from a skilled structural engineer. However, all too often, temporary works on construction sites don’t get the same level of consideration as permanent works. For a smooth construction process, adequate importance must be given to safe and effective temporary works, from the earliest stage of the project through to the end.
Some of the media coverage of failures on construction sites in recent years has related to temporary works such as scaffolding, mobile and tower cranes, excavations, and the impact to adjoining structures and utilities. While no one wants to see their project in the media for the wrong reason, when something goes wrong on a construction site the consequences are likely to be far more severe and long-lasting than some short-term adverse media coverage. This includes loss of reputation, potential legal proceedings, higher insurance premiums and loss of revenue. However, what’s far more damaging is the risk to the safety of workers and the general public. As well, delays to the project and the costs of rework or repairs could seriously undermine the construction program and the overall project outcome.
Here are a few things to consider so that your temporary works don’t cause permanent damage.
Give temporary works the same attention as permanent works
Temporary works are needed on all sorts of construction projects – whether in residential or commercial construction, or in infrastructure, mining, industrial projects or site remediation works – and they need to be treated with the same care and professionalism as permanent works. Shafts, trenches, scaffolding, and so on may remain in place when the project is complete. For example, temporary works like crane bases or retention systems or formwork may be incorporated into the permanent structure. There are often opportunities to integrate temporary works into permanent works or slightly alter the permanent works design to reduce additional costs for temporary works. In fact, it can be said that the best temporary works are no temporary works!
Allow time and budget for adequate temporary works design and development
Failures of temporary works usually stem from clearly stated criteria, inadequate design, construction and maintenance of the temporary works rather than material failures. All construction projects run on tight schedules and financial margins, so rushing and trying to reduce expenditure, or use temporary works for unintended functions not included in the design, can be at the root of the problem. On smaller, simpler projects, engineers may be viewed as an unnecessary expense. However, it’s worth comparing the cost of design, inspection and certification of temporary works with the potentially enormous costs of their failure. Spending slightly more to have a consultant review risks and provide advice on temporary works design and execution could make a huge difference.
Have the right procedural control
Australia has some of the most stringent health and safety regulations. However, there is no legislated procedural control for temporary works. On large infrastructure projects, best practice tends to draw on the British standard BS5975: 2008 Code of practice for temporary works procedures and the permissible stress design of falsework.
Having a good written procedure that sets out rules and responsibilities for all parties involved with temporary works is only one part of good procedural control. It is also imperative to have the right people with adequate qualifications, training and experience for a given task. Projects should also be sufficiently resourced and supported through the whole duration of tender and delivery. At the very least, from the perspectives of health and safety and risk, there should be a designated person overseeing and coordinating the temporary works on every site.
Build safety into design
Safety in design is a very important aspect of temporary works and it needs to extend far beyond a workshop between the client and contractor. This could be an ideal time to develop an approach that reduces or better mitigates risk during construction and should carefully consider the potential risks throughout the design and life of the works, including construction, operation, maintenance and demolition.
It is important to remember that there could be workers or other personnel on the site who have not been at the safety and risk assessment workshop and have not read all the safety background or reporting. This information could be communicated to site personnel via site meetings pre-starts. From the engineer’s perspective, a helpful approach is to embed the key safety considerations, limitations, and risks into the drawings and documentation for the actual people who are on site and doing the work.
Engage experts throughout the process
Many construction projects – from small scale to large – do not engage temporary works engineers because they don’t understand that they need the expertise, or because they underestimate the cost or time needed for building the temporary works. It is also possible that the permanent works engineer doesn’t advise on how to stage construction or design and build the temporary works. Therefore, it’s worthwhile engaging a temporary works engineer during the bid phase to provide high-level input into developing construction methodologies.
In the design development phase, engage an expert or a team of experts to compare multiple design options from a range of perspectives, and to provide preliminary advice on the volume of additional items so that implications for time and cost can be fully. The structural engineer will identify the appropriate methodology to use, and the risks (e.g. health and safety, potential problems) and benefits (e.g. time, materials, client preferences, and so on). Then they will develop design drawings and models or prepare concepts for specialist consultants to further develop schemes.
Plan and communicate well
Planning and communication are imperative, as sufficient time is needed to allow the temporary works to be carried out well, and that there’s enough in the budget to cover the costs of building, renting or buying equipment for the temporary works.
The appropriate construction methodology will depend on the project itself. For example, a standard residential tower with no unusual features may require little more than the standard approach, but an architecturally complex project would call for experienced specialists who can think outside the usual approaches and break the complex problem into simple elements that are easy to communicate and solve.
Complex projects are becoming the norm now, due to technological advancement and more sophisticated expectations. On a complex project, there may be unique problems that noone has had to manage before. The temporary works and permanent works engineers need to work together on the bones of these structures. If the temporary works engineer isn’t involved, resolution of the complexity will be left to the building contractor who may not be adequately resourced to do that.
Once the right construction methodologies and temporary works considerations are in place, engage designers who will provide advice and detailed design but also have the expertise to support construction teams as issues arise on construction sites. With the critical items, the temporary works engineer, permanent works engineer, head contractor and subcontractor should be in constant communication, so everyone knows what the risks are and what they need to be aware of.
Execute the design and get the right support on site
It’s critical that the people on site understand the details of the temporary works design and that the temporary works are constructed appropriately and conform with the designs. Unauthorised changes on site or deviations from the design can pose major risks.
Take care with proprietary equipment or systems and with standardised approaches. It is still important that these systems and solutions are assessed thoroughly for their validity in the specific circumstances, ground conditions and relevant loads.
If the temporary works on a site run into difficulties, the consequences can jeopardise the permanent works, adjacent structures or the general public – and can certainly affect the ultimate outcome of the project through delays and increased costs.
ABOUT THE AUTHOR
Barnabas Ilko is a Principal Structural Engineer at WSP, based in Melbourne, Australia. He has worked on tender phase support, detailed permanent and temporary works designs, construction staging and design management across a wide range of industries. Through years of working with contractors and stakeholders to develop safe and effective construction methodologies, Barnabas has learned from industry experts to identify temporary works and mitigate/manage the associated risks. Barnabas is well-regarded for his ability to improve construction methods and adopt design approaches that minimise project delivery time and construction costs. He also lectures about temporary works at Engineering Education Australia and has facilitated courses, presentations and webinars related to temporary works and lessons learnt from previous project experiences.