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Letters

Identifying risk

The Institution of Civil Engineers welcomes the introduction of the Construction (Design & Management) Regulations 2007 leading to the end of unnecessary design risk assessment paperwork.

The Institution does, however, emphasise that engineers must continue to identify hazards and, where practicable, eliminate and reduce risks by good design, and provide appropriate information. This will include advising contractors and others of the significant and unusual hazards and risks that remain.

In attempting to meet the requirements of the original CDM regulations many designers have used designers' risk assessments. This approach led to the production of numerous pages of risk assessments, which included many low-risk issues.

ICE fully supports the emphasis in CDM 2007 on eliminating unnecessary bureaucracy and focusing on the provision of information on significant and unusual hazards, which may not be obvious to contractor, maintenance workers or end-users.

The process of design risk assessment remains an essential designer's tool, but the emphasis in CDM 2007, the Approved Code of Practice and the Notes for Guidance is rightly on producing an effective end product, not on the process itself.

Engineering judgment should be used to eliminate or, where not reasonably practicable, to reduce hazards and risks within the construction and subsequent phases. This should be recorded in a simple, short residual significant risk register to be passed to the principal contractor and others.

John Jeffrey, chairman, ICE Health and Safety Panel, One Great George Street, London SW1P 3AA

Love me tender

Your article on the new CDM regulations (NCE, 29 March) highlights continuing confusion with regard to their interpretation and, therefore, application.

The ficonceptfl, fidesignfl and ficonstructionfl phases are the basic, sequential building blocks of any construction project. At the highest level these elements can, and often do, overlap. However, construction of a particular element should not take place in advance of the detailed design.

To place tendering firmly between the design and construction phases presumes a procurement model that harks back to simpler times before PFI, DBFO, PPP, Alliances or ECI.

The 1994 regulations use of the term fipre-tender health and safety planfl implied that this document had no post-tender function, irrespective of the procurement methodology employed. In fact the plan is an invaluable health and safety document that must remain filivefl until all design work has been completed. It is assumed that the phrase has been dropped to avoid such confusion.

The new Approved Code of Practice refers to the words fitenderfl or fitenderingfl four times compared with 55 in the previous document. This seems a positive step.

Nick Tobin, civil/structural engineer, UK Construction, National Grid, nick.tobin@uk. ngrid. com

Slab claim slam

The implication in the recent articles on the Burj Dubai (NCE 27 March and 5/12 April) that there are strength deficiencies in the structure's floor slabs or any other structural element is totally erroneous.

I have been involved with the structural design of all structural elements for the Burj Dubai project from concept design in 2003 through to the present. Carbon fibre systems can be valuable structural engineering tools but they have not been utilized for remedial structural capacity considerations on the Burj Dubai Tower project.

The slabs for the Burj Dubai project were never post-tensioned slabs and certainly were not changed to conventional reinforced slabs at the last minute. During the conceptual design phase a careful evaluation was made of various viable floor framing systems and each was reviewed by the construction manager and client.

Based upon that early evaluation, a system utilizing conventional reinforced concrete structural elements, for both walls/column and floor, was selected. These elements were designed accordingly and are continuing to be used on the project.

More than 125,000 reinforced structural concrete wall and slab penetrations are required for mechanical and electrical elements. All wall and primary slab openings were shown on the construction drawings.

Many of the smaller sleeve type openings for plumbing have varied as the contractors have come on board as is customary in this type of construction.

Stan Korista (M), director, Skidmore, Owings & Merrill, 224 S. Michigan Avenue, Chicago Il, USA

From the floor

We refer to the news article that states that carbon fibre reinforcement is being used to strengthen defective floor slabs (NCE, 29 March).

As the appointed supervision consultant to the Burj Dubai project, we wish to advise that the floor slabs on this project are not defective.

We can confirm that normal building products are being used on this project in accordance with routine construction practice and that the construction quality is world class, as would be expected on such a prestigious project.

Rod Stewart, regional managing director, Hyder Consulting Middle East Limited, PO Box 2774, Abu Dhabi, UAE

Carbon copy

The use of carbon fibre reinforcement to strengthen floor slabs is not a new technique. Indeed in 1996 when we carried out the first commercial contract in the UK to use composite strengthening it was reported in NCE.

This was at King's College Hospital, London, where 1,300m of carbon fibre reinforced composite plates were installed on the ribbed soffit of the roof slab to allow an additional floor to be added.

I recently inspected the plates, which are on an exposed painted soffit . The installation is as good as the day it was installed.

Since then we have designed and installed hundreds of composite strengthening schemes that can be 10m of plate around a service hole - the largest to date has been 15km of plate on a residential tower block. The material prices are now considerably lower and there is a wide range of fibres and plates available.

What surprises me is the way industry has been slow to recognise and adopt composite materials. There are some limitations with regard to fire and modulus of elasticity but if used wisely in combination with steel and concrete I am sure it can, and will, provide some considerable benefits to the construction industry.

John Drewett, director, Concrete Repairs, Cathite House, 23a Willow Lane, Mitcham, Surrey CR4 4TU

Off centre

So where is the next-but-one generation of civil engineers coming from? What will ensure that bright and imaginative youngsters become inspired to think of taking up civil engineering as a profession?

At the Severn Bridges Visitors Centre in Bristol school parties and families out for the weekend can see how the two Severn crossings were designed and constructed, and appreciate the skill and ingenuity that were used to create these two world-class structures. Which is why it is so desperately disappointing that the engineering industry seems unwilling to support the centre.

As new trustees, we have found it most disheartening that so few organisations are willing to sponsor the work of the centre and that many of the firms approached do not even reply to requests for help.

Without nancial support, the centre cannot survive and the civil engineers that might otherwise have led the industry in 40 years time will become lawyers or accountants.

John Evans (F) and Andrew Hewitt (M), Severn Bridges Visitors Centre, Bristol BS35 4NQ

Wave goodbye

The headline fi2012 stadium delayed due to complex designfl (NCE 5/12 April) highlights a problem common to many structures that are essentially fitemporaryfl.

If we are not careful history will redefine the engineering profession as those who can spend twice as much and double the time as any fool can do in the half of both.

Just take the Docklands Light Railway (DLR) platform roof at Stratford, east London.

It has required extensive temporary works and its wavy shape meant that every piece of cladding had to be hand cut.

We read that the construction industry is overheating and complicated structures will bypassed for efficient and easily constructed designs that can be manufactured off-site and erected on a just- in-time basis.

If this DLR roof is a foretaste of the designs for the temporary Olympic venue then you can cross out 2012 and write 2016.

Derek Julier (M), julierdl@yahoo. co. uk

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