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Firstly, we would like to apologise for the delay in posting these latest updates. The summer has been exceptionally busy for 48.3 as we have completed a successful recruitment process, delivered some large and complex design schemes and worked to partner with existing clients to deliver an unrivaled level of service.

Temporary Works Forum (TWf)

The last meeting of the temporary works forum was held on the 3rd September at the Chartered Institution of Highways and Transportation offices in London. The meeting was very well attended by representatives from all the supporting companies of the TWf including Ben Beaumont from 48.3 Scaffold Design Ltd.

The meeting opened with a very interesting presentation from Mr Alex Gilbert, Associate Director at Amey, regarding the temporary works challenges encountered on the Hammersmith Flyover. The content and explanation provided by Mr Gilbert was insightful and the key learning outcomes for all parties on the project provide excellent lessons for all members.

One of the interesting discussion points of the meeting were the lessons learnt from recent collapses and/or failures. This is an opportunity for members to listen and learn from the more experienced members of the forum and take away valuable information. A recent tower crane collapse highlighted fundamental design flaws and serious lapses in procedural control, providing lessons in design method and the importance of adhering to industry best-practice in temporary works control in the form of BS 5975.

Finally, the TWf will soon be issuing the first version of its guidance notes on the ‘Design of Hoardings’. The TWf working group headed by Peter Pallett has been working hard to complete the document which will fill a gap currently present within the guidelines for temporary works in the UK. 48.3 would like to thank the TWf working group for all their hard work in completing this guide and are looking forward to using it in the near future.

For more information regarding the Temporary Works Forum visit their website: www.twforum.org.uk

Online Debate: System Scaffolding: Mixing of two manufacturers products

There has been much debate and discussion in recent months, both online and elsewhere, regarding the viability of mixing two different system scaffolding products i.e. Plettac Contour with Scafom Ringscaff or Layher Allround.

In summary the main points are firstly, can this be done? And secondly, if it is done, how is it assessed and which manufacturer’s information is used.

The answer is not straightforward. Some manufacturers state that their products can be mixed, others do not. The ones that do, state that in most cases you must acquire a full structural design for your ‘mixed’ scaffold. Which leads us straight to the question: “Who is going to undertake a full structural design of a mixed system scaffold?”

Before we give our thoughts on this matter, we must first acknowledge that this is not the only issue here, there are many other related points to be addressed such as:

  • Training: CISRS cards for scaffolders competence are in one specific system, not mixed systems.
  • Technical Manual of component properties and capacities.
  • Installation and erection guides.
  • Product liability, indemnity cover and conformity.

The design issue obviously relates to some of the points above, however the key points overriding the rest are these: If 48.3 were asked to produce a full structural design for a mixed system we would need to know the exact location of each different component i.e. which type of ledgers were used where, which type of brace were used where etc. - a huge task. Secondly, if you could derive this information, how could it be guaranteed on site?

You would then need to create a full analysis model of the structure. The reason being, the tests completed for individual components assume either laboratory conditions with no other affecting components, or other linked components of the same system. Therefore, stated test values for each set of components can not be used accurately in a mixed scenario as this was not the test case when determining their capacities. Even if they could, the number of different possibilities in test configuration is infinite. So we would have to build a model.

Creating the model is very time consuming when compared to standard calculations you would complete for a single type system scaffold. You would then be required to perform second order analysis of the model (as required by BS EN 12811) as you do not have any alternatives - you are not using the test results for a particular system, where this analysis has been completed by the manufacturer / supplier, nor can you use a system of effective lengths as you could not rely on the component capacities in this configuration.

This leads to a couple of simple questions - who is going to pay for it? In this economic climate, when the drive for “more for less” is at the heart of all design, who would want to foot the bill for the additional design cost in completing the tasks outlined above. Secondly, who has the time to complete it? Competent scaffold design engineers are exceptionally busy, so finding someone with the time to do this properly would be difficult.

48.3 have never completed a design using a mixture of different system components nor have we ever been asked to. Where specific manufacturers state that their components must not be mixed, we will not mix them.

There are other associated issues we have not mentioned here - this topic is a big one. If you would like to read an interesting debate on the subject, head to Linkedin: http://linkd.in/Ol6t5R