In complex lifting, most calculations are checked. What is checked less often is the boundary between the parties who made them. One party owns the permanent design, another the erection method, another the temporary works, and the contractor carries execution risk. On paper everything is assigned. The behaviour of the system as a whole, which depends on how those pieces fit, can belong to nobody.

A familiar scenario

Take a heavy crane arriving on a bridge site. The lifting contractor assumes the designer has verified the bearing capacity of the crane pad. The designer assumes the contractor will confirm the actual site conditions. The main contractor assumes the two are talking to each other. The wording that allows this is familiar: “coordination as required”, “shall liaise with”, “subject to approval”.

This is an illustrative scenario, not a documented case. The pattern, in which each party believes another owns the check, tends to surface when the equipment is already on site, idle plant is expensive and programme float is thin.

Schematic of an illustrative scenario in which a designer, a lifting contractor and a main contractor each assume another party has checked the same condition, linked by contract wording such as coordination as required and shall liaise with, leaving a gap that is discovered at mobilisation
An illustrative scenario, not a documented project. Conceptual schematic; HSE guidance on the temporary works co-ordinator and BS 5975 referred to in the text. Diagram: EE&HL Network, 2026.

Why it is hard to see in advance

Engineering and procurement are often aligned on objectives but not on risk. Both views are reasonable; they describe different versions of the same risk.

1 — The scope line
Procurement sees what is defined
Procurement works with defined scope, commercial clarity, comparability and defined responsibilities. Construction-phase risk does not sit neatly inside a scope line.
2 — The temporary state
Engineering sees what changes
Engineering thinks in load paths, temporary conditions, sequencing logic and what happens if assumptions change. A lot of that risk lives between sequences and inside temporary states.
3 — The handover
Responsibility moves when conditions move
When conditions deviate from plan, responsibility shifts with them. Translated late, or only in technical language, the risk resurfaces downstream as programme pressure, late changes or constrained execution.

What the UK framework already says

HSE’s temporary works guidance is explicit that coordination is its own job. It says that coordinating temporary works is not automatically the responsibility of the engineer carrying out the design work, and that coordination is a much wider role: planning where and when temporary works will be needed and ensuring that they are correctly installed, used, checked and maintained. HSE also notes that there is no legal requirement to use the job title or the recommended process, and that BS 5975 provides an industry consensus view of good practice. The temporary works co-ordinator is one example of an interface being turned into a named responsibility.

Where the boundary shows on real projects

At the Millau Viaduct, the earliest release of the temporary towers was set by the stay-cable installation schedule, not by the erection contractor’s own, as the Millau case study sets out. At Skarnsund, the cost of tidal windows and design changes arrived on the contractor’s side during construction, and the Skarnsund case study records the contractor’s takeover. Neither case is a dispute over a clause. Both show a condition set in one place being paid for in another.

What a better-defined boundary looks like

In practice a well-defined boundary names the checker, the input and the date for each shared assumption, rather than leaving the wording at “coordination as required”. That is an editorial observation, not a contractual recommendation, and it does not replace legal advice on any particular form of contract.

For related patterns see What Is Erection Sequence Risk?, Temporary Works & Erection Strategy and the insight Why Removing Temporary Works Can Be Riskier Than Installing Them.

Related case studies: Millau Viaduct · Skarnsund Bridge · Singapore Sports Hub · Perdido Spar

Sources: Health and Safety Executive — Temporary works FAQs (the temporary works co-ordinator role; no legal requirement to use the title; BS 5975 as consensus good practice); BS 5975-1:2024 — Management procedures for the control of temporary works, British Standards Institution; EE&HL Network — Millau temporary towers release sequence, with its primary sources; EE&HL Network — Skarnsund Bridge, with its primary sources. The crane-pad scenario is illustrative and is not drawn from a documented project. Contract wording quoted is typical phrasing, not taken from a specific contract.

Frequently Asked Questions

It is the risk that sits between the parties to a lift, for example the designer, the lifting contractor and the main contractor, where each assumes another has checked something and no one owns the check. It tends to surface when equipment is already on site.

HSE says coordinating temporary works is not automatically the responsibility of the engineer carrying out the design work. Coordination is a wider role that includes planning where and when temporary works are needed and ensuring they are correctly installed, used, checked and maintained.

Because it assigns a duty without naming who checks what, against which input, by when. Each party can read the clause as the other party’s responsibility.

HSE says there is no legal requirement to use this job title or the BS-recommended process, but that BS 5975 provides an industry consensus view of good practice. The legal obligation is that the party in control must allocate and carry out the work in a manner that does not create unacceptable risk of harm.