The Employer's responsibilities on Site, in NSSS terms, are given in 8.2.1. Proper hard- standing areas and firm road accesses suitable for the delivery of heavy steel members on standard vehicles are needed. Even more importantly, suitable areas are needed for the safe operation of the Steelwork Contractor’s plant during his erection operations. There is widespread demand that steel erectors should work as far as possible from mobile elevating working platforms [MEWPs]. This means that the Site area the Employer needs to prepare for plant operation now extends to much of the Site and greatly exceeds that which is needed solely for the positioning and operation of cranes. Thus, to assist the clarification as to whether the Site is safe for steel erection to proceed, the Safe Site Handover Certificate [SSHC] includes a checklist of such items (see 8.3.1(i) and Ref. 5). The stage at which the Site is handed over for steel erection to commence is too late to find out that the ground bearing pressures are unsuited to the safe operation of the Steelwork Contractor’s cranes and MEWPs. Hence, the ground bearing capacity should be specified in the Pre-Tender Health & Safety Plan.
The Site should be free of standing water, and the Employer may have to pump foundation pits clear of water so that work at foundation level can be carried out.
He also has the duty to be aware of positions of all new and existing underground services, and to acquaint the Steelwork Contractor with details of any that are in the working areas being used. If any overhead obstructions exist that would prevent the proper operation of cranes for use in erection, the Employer should arrange temporary or permanent removal. This requirement includes the removal of electric wires and cables that might be a safety hazard during erection and the clear marking of routes for cranes and similar vehicles within the Site.
In 8.2.2, the Steelwork Contractor's responsibility includes the design of any temporary supports for crane footings. Timber spreaders, or other means should be provided to ensure that the ground bearing capacity under the crane supports is not exceeded. The Steelwork Contractor should be fully aware of the requirements of BS 7121: Code of practice for safe use of cranes, which includes including inspection, testing and examination of cranes.
8.3 — SAFETY
Safety is re-emphasised once again in these clauses. In 8.3.1 reference is made to parties’ obligations for the safe erection of the structure under the CDM Regulations and the SSHC, and with respect to the appropriate sections of BS 5531: Code of Practice for safety in erection of structural frames, which deals with steel, timber, precast concrete and plastic frames.
The Steelwork Contractor's responsibilities for safety are outlined in 8.3.2, and include compliance with both the Employer's rules for operating the Site and current legislation. Much of this is now included in the CDM Regulations and, in particular, in the Construction Health & Safety Plan.
Safety is the subject of much legislation in addition to the CDM Regulations and it is embraced in new European directives. A publication that contains safety guidance for site-based staff is the Erector's Manual, available from the BCSA (see Ref. 14).
8.4 — STABILITY
These clauses are intended to ensure that the structure being erected is fully stable at all times. In this context it means three things:
the stability of members being lifted and until properly restrained,
the strength and stability of components to resist temporary erection loading, and the overall stability of the structure until permanent features are added.
To avoid instability of individual members or the part-erected structure as a whole, temporary restraints may be necessary for any of these categories until all steelwork and other permanent restraints are in position. Short length components are not likely to have stability problems; however, long components and particularly long, deep components may be expected to require restraints when they are being lifted and until some, or all, permanent members are in position. Particularly vulnerable components are:
Lattice girders with single gusset plate joints.
Narrow flanged beams and plate girders that will need more than one permanent restraint after erection.
Members to form steel/concrete composite floor beams having to support wet concrete without restraints.
Members relying on metal decking to stabilise them until other parts are in position. Members having to resist high wind loads in the temporary condition.
Members in significant compression.
Special attention is paid in 8.4.1 to temporary restraints, which are a design requirement until permanent features are built. This is because it is considered that the Engineer, being the designer, knows which permanent features provide restraints in the finished structure. He is also aware of the design stresses in the components. On the other hand the Steelwork Contractor, when building a complicated frame, may be unaware of these matters. It is therefore incumbent on the Engineer to advise the Steelwork Contractor about these features, particularly if it is not obvious from reading the design drawings, as they constitute hazards under the CDM Regulations.
The Steelwork Contractor is required to design and provide any temporary bracing and restraints needed. Full details should be included in the erection method statement.
The purpose of 8.4.2 is to make it clear that the Employer and other subcontractors should not rely on the temporary restraints used for erection purposes being kept in position after lining and levelling of the steelwork is complete unless the Steelwork Contractor has been specifically requested to leave the temporary restraints in position. If there is any possibility of the structure distorting before walls and cladding are in position, then temporary bracing should obviously remain after steel erection is complete. However, the Steelwork Contractor should be informed of the requirement so that it can be properly programmed and costed (see TABLES 1.4(viii) and