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Temporary Works
John Carpenter
It’s all temporary works.
From this….. …..to this
Content
• Background & History• Types of temporary works• Differences: permanent works/temporary works
• Roles & responsibilities• Issues of which you need to be aware.
Definition
• Defined as:’parts of the works that allow or enable construction of, protect, support or provide access to, the permanent works and which might or might not remain in place at the completion of the works
Note: examples of temporary works are structures, supports, back‐propping, earthworks and accesses’
(BS5975: 2008)
History
1970sBragg
BS 5975 (latest is 2008)BS EN12812:2004
(also SCOSS Topic Paper)
Loddon Viaduct collapse 1972
Bragg‐1
• A lack of clarity in the division of responsibility.• A failure to reflect the ‘high risk’ nature of falsework in the design and site controls.
• The essential need to provide robust means of ensuring lateral stability, and specifically so at forkhead level.
• The need to discard damaged or distorted items.• The need for stiffeners at all load bearing points in steel grillages
Bragg‐2
• Falsework requires the same skill and attention to detail as the design of permanent structures of like complexity, and indeed falsework should always be regarded as a structure in its own right, the stability of which at all stages of construction is paramount for safety.
Designers: role in temporary works
• Permanent Works Designer (PWD)– Facilitator– Envisages means of construction– Information transfer– Interaction– May undertake TW design (rarely)
• Temporary Works Designer (TWD)– Designs (ERIC)– 4Cs: competence, communication, co‐operation, co‐ordination
How do you locate these designers?
Duties do not differ: permanent works/temporary works
Permanent Works
Temporary Works
(construct, maintain,
use,decommission)
Possible critical interface
Permanent WorksDesigner
Temporary Works Designer
Co-operationCo-ordinationInformation
Excavations
• Space• Criticality (i.e. adjacent buildings)• Ground conditions (i.e. base data)• Sequence?
Role of the PWD?Role of the TWD?
TrenchesFoundationsBasementsCaissonsTunnels
Basements
Elevated
Did PWD envisage and plan for this?
Has the TWD followed appropriate design processes?
ScaffoldingTrestlesBirdcageTowersProps
Openings
Proprietary systems
Source, conditionLoads (ULS, WL?)
Lateral stability
Checks & reviews?
Foundations?
KwikformPeri
Craneage & MEWPs
The Notification of Conventional Tower Cranes Regulations 2010
Safe crane campaignhttp://www.strategicforum.org.uk/towercranes.shtml
MEWPS
Space.Foundations.Mobile cranes
Basements
APS‐ access industry forum
LiverpoolBelfast Law Courts
Failures
Lack of competency?Mis‐use? Poor information and control? Design related?
– Permanent works design?– Temporary works design? SCOSS
‘3Ps’
Differences: PW/TW
• Temporary Works– Short term– Often fragmented supply chain– Split design (e.g. temporary works and foundations)
– Re‐used material– Full loading– Dismantled
Responsibilities‐1
• Permanent works designer (PWD)• Temporary works designer (TWD)
• CDM‐C‐ later
• Principal Contractor• Contractor
ERIC
Eliminate Reduce Inform Control
ConstructionSkills Guidance for Designers
Designer Responsibilities
• Straightforward PW design with adequate space and no structural interaction: No PWD involvement
• If not, then the PWD must:– Be satisfied there is a reasonable means of construction
– Inform the contractor of the key issues
Responsibilities‐2
• Contract– Supply chain– Often no link between PWD and TWD
• Statute– Overrides contract– Requires action regardless of contractual make‐up
Codes and guides
• BS and EN codes, Guides, Industry guidance
Current situation– BS5975– BS EN12812– Others (e.g. BS EN12811)
Current codes
• BS5975:2008– Code of practice for Temporary Works procedures and the permissible stress design of falsework
• BS EN12812: 2004– Falsework‐performance requirements and general design
– Type A, B1, B2
BS EN12812: 2004Falsework‐performance requirements and general design
Type A, B1, B2 (Design Classes)
Type A: simple constructionsmaterials to comply with appropriate codes; no specific design specified
Type B1: B2: formalised design and data.(B1 is the most defined).
Key persons
• Temporary works co‐ordinator (TWC)– Temporary works supervisor (TWS)
• Appointed person (AP)
Check during review of Corporate Competency and Construction Phase H&S Plan
TWC‐ Competency
• What should this look like?• HSE advice:
• But, in order of priority:
Have experience of the relevant types of temporary works.Have completed formal TWC training.
Hold a Degree / HND in civil/ structural engineering.Be a Chartered Civil / Structural Engineer
relevant experience,formal TWC training andprofessional qualifications.
TWCs should have the competence and authority to be effective.
Corporate Comp.ConstructionPhase Plan
Issues• Procedural
– Competencies: TWC– Clarity of responsibility– Information from designers– Adhering to BS5975/EN12812– Safe design: designed to be built.
• Technical– Lateral stability– Foundations– Condition of equipment– Clarity as to loads: ULS/SLS/Working load
Good practice
• Integrated design• Appointed TWC (and TWS) and AP
• Use of Guides and ‘good practice’
• Use of Temporary Works Forum (TWf)
Temporary Works Forum (TWf)
• Give authoritative guidance and, when required, professional leadership to the industry
• Consider aspects of permanent works and interfaces between permanent works and temporary works
• Consider both current practice and likely development• Be aware of trends and innovations in design, construction and use.• Consider whether unacceptable risk exists or might arise in the future• Consider whether further research and development appears desirable• Encourage others to avoid duplicating work in hand elsewhere.• Keep a watching brief on international issues
Summary
• TW comes in all shapes and sizes• CDM does not distinguish between PWD and TWD
• 4Cs are vital• TW have specific characteristics
Good TW practice is vital: it is a high risk activity
CDM‐Cs are able to play an important part in all this
No problem!