CDM 2015 Designer Duties – Designing for maintenance

CDM 2015 Regulation 9 requires designers to eliminate or reduce risks to those involved in maintenance so far as reasonably practical or, if that isn’t possible, to provide information on significant residual risks.  Designers may not be aware of the guidance available to help them.  To address that, this article by Mike Webster provides an overview of the issues and highlights the guidance available to civil and structural engineers on contemporary industry practice.

Regulation 9 – Requirements of the CDM 2015 Designer Duties 

Structures degrade with time^[1].  That degradation will require maintenance in the form of cleaning, inspection, routine maintenance, minor repairs, major repairs and replacement.  This will help to maintain a good appearance, efficient operation and the safety of users and members of the public.

Maintenance can take the form of:

• planned maintenance to keep the structure in good order; or
• reactive maintenance when immediate concerns are spotted.

In both cases, safe access to the structures is required.

Regulation 9 of CDM 2015 requires designers to: ‘eliminate, so far as is reasonably practicable, foreseeable risks to the health or safety of any person … (b) maintaining or cleaning a structure.‘

CDM 2015 Regulation 9 also notes that: ‘If it is not possible to eliminate these risks, the designer must, so far as is reasonably practicable (a) take steps to reduce or, if that is not possible, control the risks through the subsequent design process; (b) provide information about those risks to the principal designer; (c) ensure appropriate information is included in the health and safety file.’

What does CDM 2015 Regulation 9 mean in practice for designers?

In practice, Regulation 9 boils down to three key principles^[2] for designers.  These are:

1. Designs shall be safe to construct, maintain, operate and de-commission – designers may assume that these activities will be undertaken by competent people (who will be able to manage normal construction / operational / repair risk arising from the design)

2. Designs shall comply with contemporary industry practice as regards health and safety – unless there is good reason for not complying

3. Information on significant residual risks shall be communicated to those who need to know – these are the significant risks, not high risks (i.e. those risks that are not likely to be obvious to a capable designer or contractor, or are unusual or are likely to be difficult to manage effectively)

A simple way for designers to remember these duties  is the Eliminate-Reduce-Inform-Control (ERIC) framework^[3].

Designing for maintenance

Following the ERIC framework, a CDM 2015 designer would need to:

• Eliminate the need for maintenance as part of the design;
• if that is not possible,
• Design the structure so that future maintenance is reduced; and
• Design the structure so that when maintenance is required it can be carried out safely;
• if that is not possible,
• Provide relevant information on any significant residual maintenance risks that may remain;
• and, if necessary,
• Design in any control measures that may help those carrying out the maintenance (e.g. access for inspection or cleaning), but the responsibility for producing a ‘safe method of work’ belongs with those in charge of the work itself.

Examples of this approach include:

ERIC	Design activity	Examples
E	Eliminate the need for maintenance	Use an integral bridge – this will remove the need for bearings and movement joints, both of which require inspection and replacement Design for the appropriate environment – this will potentially eliminate the need for maintenance if sufficiently durable materials are used
R	Reduce future maintenance	Use longer life paint or galvanising – to reduce the amount of maintenance activity Provide adequate falls to roofs – to prevent a build-up of water or debris
	Maintenance carried out safely	Design in permanent connections and ties – to allow scaffolding or other work platforms to be connected Design bridge bearings to allow for inspection and replacement – so that inspectors can see them clearly and contractors can jack the deck to replace them
I	Provide information	Provide information on areas of a structure that have only been designed for light loads – routes to plan trooms may be subject to heavy loads if replacement plant is required Provide information on areas needing access where normal methods of tying scaffolding may not be feasible –  such as facades that have no opening windows and cannot be drilled Requirements for inspection and maintenance of multi-storey car parks should be clearly set out – so that they can be included in a life-care plan
C	Controls	Incorporate permanent access facilities in bridges – such as abutment galleries to avoid inspectors having to use MEPS

Design issues for particular types of structures

Bridges

Bridges are exposed to relatively severe environments.  The major issues with bridges relate to:

• Leaking or damaged movement joints
• Ageing bearings
• Blocked or broken drainage
• Damaged waterproofing
• Corrosion of reinforcement or other metallic inserts

In the UK, General Inspections are required at two-year and Principal Inspections at six-year intervals.  These inspections are vital to identify potential problems at an early stage when they can be addressed with relatively minor works.  However, inspection can only be carried out effectively if inspectors can work in a safe and reasonably comfortable environment.

CIRIA Report 155^[4] notes that: ‘When establishing the layout of a scheme, designers should consider how inspections can be economically carried out, utilising, as far as possible, readily available plant and equipment.  The cost of traffic delays due to temporary lane or road closures and the cost of associated traffic management measures should be taken into account.  For some structures, it may be appropriate to incorporate permanent access facilities, such as abutment galleries, span cradles, or simply cast-in stainless steel fixings.’

Detailed guidance is available for designing bridges for durability^{[5, 6]}, maintenance^[7], and buildability^[4].

Building structures

Typical building structures are exposed to less severe environments than bridges (unless they are near the coast).

However, there is still a need to inspect these buildings periodically, and designers will need to consider whether the building can be accessed easily and safely.  Where access equipment is required for cleaning, maintenance or repair of a structure those requirements should be identified and passed to the Principal Designer for inclusion in the Health and Safety File.  If any permanent or temporary access equipment is included in the design then suitable means of fixing this equipment to the structure needs to be provided.  The requirements for such equipment need to be communicated to the civil/structural engineer by the relevant designer early enough for the loadings and fixing details to be incorporated into the structural design.

Plant may also need to be replaced during the life of the building.  Consideration should be given to whether there are safe routes for removing and replacing large / heavy plant in plant rooms and information should be provided.  This is particularly the case if the plant room is in a basement or on a roof, or if some parts of the structure have been designed for relatively light loads. The layout of plant rooms should also be designed so that mechanical lifting aids can be used when carrying out maintenance and replacing components.

To help CDM 2015 designers, a range of guidance^{[8, 9]} is available for the design of building structures, the design of those structures as workplaces^[10] and design specifically for maintenance^[11].  Guidance is also available to address health issues^[12] and safe work at height^[13] when designing for maintenance.

Multi-storey car park structures

Multi-storey car parks are exposed to environments much closer to those of bridges than buildings but, historically, have been designed to guidance applicable to buildings. Failures in some older car parks have been observed as a result of:

• Concrete degradation
• Reinforcement corrosion
• Failure of edge barriers

Extensive repair work has also been required on some older car parks.

Waterproof membranes, lifts, electrical and data systems may well have to be replaced during the life of the car park.  Consideration of this should be included in the design.  Cladding and/or edge protection may well be damaged by accidental vehicle impact.  Ease of replacement should be considered in the design.

Guidance is now available both for the design of new car parks^[14] and for the development of life-care plans based on regular inspection, assessment, maintenance of management^[15].

Further information

A summary of what designers should do to minimise the risk of deterioration in new structures is available in this post.   A summary of the influence of design and detailing on the safety of deteriorating concrete structures is available in this post.

A brief summary of eight key changes to the CDM 2015 Regulations from CDM 2007 and what those changes mean in practice is provided in this post.

A summary of published answers to frequently asked questions relating to the CDM 2015 Regulations is provided in this post.

Detailed clause-by-clause comparisons of the changes between the CDM 2015 Regulations and CDM 2007 are available on the MPW R&R web site for Clients, Designers and Principal Contractors / Contractors.

I gave a 25-minute presentation at the Institution of Structural Engineers Small Practitioners Conference on 26 June 2018 on understanding the CDM 2015 Designer Duties as they relate to civil and structural engineers.  The video of my presentation and the accompanying slides are available in this post.

An overview of the issues involved in CDM 2015 Designer Duties – considering temporary works in permanent works design are discussed in this post and signposting is provided to the guidance available to civil and structural engineers on contemporary industry practice.

The HSE web site contains a range of information on CDM 2015 including the guidance on the regulations, a short guide for clients and a guide on construction phase plans.

The CITB web site contains industry guidance for each of the duty holders.

References

[1]  Webster. M P: Impact of deterioration on the safety of concrete structures – what can designers do to minimise risk?, 2016.  (http://mpwrandr.co.uk/impact-of-deterioration-on-the-safety-of-concrete-structures-designers/)

[2]  Institution of Civil Engineers: Design Risk Management Guidance, September 2018.  (https://www.ice.org.uk/ICEDevelopmentWebPortal/media/Documents/Disciplines%20and%20Resources/Best%20Practice/drm-guide-version-1-3.pdf)

[3]  Carpenter, J: ‘Risk management with ERIC’, The Structural Engineer,88 (7), 7 April 2010.

[4]  Ray, S S; Barr, J and Clark, L A: Bridges – design for improved buildability, CIRIA, Report 155, 1996.

[5]  The Design Manual for Roads and Bridges: Design for durability, Standard BD 57 (DMRB 1.3.7), August 2001.  (http://www.standardsforhighways.co.uk/dmrb/vol1/section3/bd5701.pdf)

[6]  The Design Manual for Roads and Bridges: Design for durability, Advice Note BA 57 (DMRB 1.3.8), August 2001.  (http://www.standardsforhighways.co.uk/dmrb/vol1/section3/ba5701.pdf)

[7]  Highways England: Designing for maintenance, Interim Advice Note IAN 69/15, April 2015.  (http://www.standardsforhighways.co.uk/ians/pdfs/ian69_15.pdf)

[8]  Ove Arup & Partners and Gilbertson, A: CDM 2015 – Construction work sector guidance for designers, CIRIA, Report C755, Fourth edition, 2015.  (https://www.ciria.org/ItemDetail?iProductCode=C755&Category=BOOK&WebsiteKey=3f18c87a-d62b-4eca-8ef4-9b09309c1c91)

[9]  Carpenter, J: Designing for safer concrete structures, The Concrete Centre, CCIP-043, November 2011.  (https://www.concretecentre.com/Publications-Software/Publications/Designing-for-Safer-Concrete-Structures.aspx)

[10]  Gilbertson, A: CDM 2015 – Workplace ‘in-use’ guidance for designers, CIRIA Report C765, Second Edition, 2015.  (https://www.ciria.org/ItemDetail?iProductCode=C756&Category=BOOK&WebsiteKey=3f18c87a-d62b-4eca-8ef4-9b09309c1c91)

[11]  Iddon, J and Carpenter, J: Safe access for maintenance and repair – Guidance for designers, CIRIA, Report C686, 2009.  (https://www.bsria.co.uk/information-membership/bookshop/publication/ciria-safe-access-for-maintenance-and-repair-guidance-for-designers-second-edition-2009/)

[12]  Crossrail: Healthy by Design.  (https://learninglegacy.crossrail.co.uk/wp-content/uploads/2016/01/HS35_HealthyByDesign-Web-Version.pdf)

[13]  BSI: Code of practice for the design of buildings incorporating safe work at height, BS 8560:2012  (https://shop.bsigroup.com/ProductDetail/?pid=000000000030235508)

[14]  Institution of Structural Engineers: Design recommendations for multi-storey and underground car parks, Fourth edition, March 2011.  (https://shop.istructe.org/design-recommendations-for-multi-storey-and-underground-car-parks-fourth-edition.html)

[15]  Institution of Civil Engineers: Recommendations for the Inspection, Maintenance and Management of Car Park Structures, Second edition, 2018.  (http://www.icebookshop.com/bookshop_main.asp?ISBN=9780727758392)

About the author:

Dr Mike Webster is a chartered civil and structural engineer (FICE, FIStructE) with over 30 years’ experience.  He specialises in construction and structural safety, CDM and risk, and founded MPW R&R to provide Consulting, Forensic and Expert Witness services in those areas.

Mike has worked on the design, inspection, appraisal and site supervision of building, bridge and car park structures.  He has developed guidance for assessing the safety of existing structures.  Mike led an independent review of CDM 1994 and the independent evaluation of CDM 2007.  He also led the review of the use of CDM 2007 in the construction of London 2012.

Mike has been instructed as an expert witness by both defence and prosecution teams in cases involving allegations of gross negligence manslaughter, breaches of the Health and Safety at Work Act and the CDM Regulations and the appeal of enforcement notices.  These cases have involved the construction, maintenance and demolition of a range of building, bridge and industrial structures.

Mike is the author of around 20 published reports and papers on construction health and safety and the CDM Regulations.  He is also the author of a range of articles on CDM 2015.   He is a member of Structural-Safety and the Institution of Structural Engineers Health and Safety Panel.

For more information email Mike at mike.webster@mpwrandr.co.uk or give him a call on 07969 957471.