What makes a lift a critical lift?

Consequence out of proportion to the operation, not weight. The usual triggers are a unique or long-lead load, people working under or near the path, live plant or services beneath it, two cranes sharing the load, any operation that turns or upends the load, working above roughly 75 to 80 percent of chart, a blind lift, and ground or a supporting structure whose capacity has not been proven. Any single one of those should push a lift into the critical category, and the plan should say which one did.

What has to be in a critical lift plan?

Fifteen things, and each number needs a provenance line. What is being lifted and from where to where; the weight and where it came from; the centre of gravity with its tolerance; the crane, its configuration and the specific chart page; the duty at the governing radius rather than at the pick; the rigging arrangement with every accessory rated; the lift points and their design basis; the ground or supporting structure with its check; the load path as a drawing; clearances; the people and their competences; the exclusion zone and how it is enforced; a numbered sequence with hold points; measurable limits and abort criteria; and the emergency arrangements.

Who writes and approves a lift plan?

A person competent to plan lifting operations, with the authority to impose the controls the plan contains. That authority matters more than the job title: a plan written by somebody who cannot enforce a slew restriction or a wind limit is a document rather than a control. The supervisor who will run the lift should be part of the planning rather than meeting the sequence for the first time on the day, and the operator should have seen the plan before being directed by somebody who has.

Why does the ground check belong in the lift plan?

Because the plan's controls are inputs to it. In this article's worked example the ground check fails at 126 percent as first written and passes at 94 after two changes, and neither change was structural: the permitted slew arc was restricted, which lowered the worst outrigger load from 980 kN to 910, and the standing area was replaced by a working platform confirmed at 500 kPa. Keeping the calculation somewhere other than the plan is how a plan comes to describe a different lift from the one that was checked.

How do I review a lift plan quickly?

In this order: find the governing case, check the weight's provenance, check the chart page matches the stated configuration, check the duty at the governing radius rather than at the pick, follow one force from the hook all the way into the structure, go straight to the ground check and find out who confirmed the allowable, read the abort criteria for whether they can be measured, and compare the drawing against the text. Reading front to back is how a reviewer runs out of attention exactly where the calculations are.

Critical lift plan: what a reviewable one holds

The short answer

A lift plan is a document somebody has to be able to review. If a reviewer cannot find the governing case, the assumption behind it and the person who owns it, the plan has failed regardless of whether the lift succeeds.
The plan's controls are inputs to the calculation. In the worked example the ground check fails at 126 percent and passes at 94, and the change was a restricted slew arc and a confirmed platform, not a bigger mat.
Every number in a plan needs a provenance line: where it came from, who owns it, and what happens if it turns out to be wrong. A number with no provenance cannot be checked and cannot be challenged.
The commonest omission is the ground. The rigging is usually calculated, the crane chart is usually attached, and the pressure under the mats is usually a sentence.
Write the abort criteria before the lift, not during it. A criterion decided in the moment by the person under pressure is not a criterion.

What makes a lift critical

Not its weight. A lift is critical when the consequence of getting it wrong is out of proportion to the effort of getting it right, and that is a judgement somebody has to make and record.

There is no universal weight threshold, and organisations that set one usually discover its limits within a year. What actually matters is a small number of conditions, any one of which should push a lift into the critical category.

01Would failure be out of proportion to the lift?
The load is unique, long-lead or irreplaceable
Critical. A vessel with a nine-month lead time is a schedule failure as well as a lifting one.
People are working under or near the path
Critical, and the plan has to say how the exclusion is enforced.
Failure would hit live plant, a live service, or a structure
Critical. A dropped load onto a running line is a different event from a dropped load onto a yard.
02Is anything about the lift outside routine practice?
Two or more cranes share the load
Critical. The load share is indeterminate and needs its own treatment.
The load is turned, upended or tailed
Critical. The geometry changes through the operation and so does everything that depends on it.
The crane works above 75 to 80 percent of chart
Critical in most organisations, and it is a sensible line. Near the chart limit small errors in weight or radius stop being small.
Blind lift, or the operator cannot see the landing
Critical. The plan has to define the signalling and its failure mode.
03Is the supporting ground or structure unproven?
Ground with no confirmed bearing value
Critical until it is proven, and the plan carries the proof.
Setting up on a slab, deck or bridge
Critical. Somebody has to check the structure for the outrigger loads.
Excavation, slope or buried service in the influence zone
Critical, and it is temporary works before it is a lift.

Whatever your threshold, write down which condition triggered it. A plan that says "critical lift" without saying why has already lost the reader who has to decide how carefully to read it.

What a reviewable plan contains

Fifteen things. A plan missing any of them is not necessarily unsafe, but it is unreviewable, which is a different and more insidious problem.

Contents of a critical lift plan

01What is being lifted, and from where to whereItem identity, drawing reference, pick position and set position, both with coordinates or grid references.
02The weight, and its provenanceWeighed, calculated from a model, or taken from a data sheet, with the source named and the contingency stated separately.
03The centre of gravity, and its toleranceA position with an envelope around it, and the statement that the worst position in that envelope was the one checked.
04The crane, its configuration and its chartMachine, counterweight, boom and jib configuration, outrigger extension, and the specific chart page with its revision.
05The duty at the governing radiusThe percentage of chart at the worst radius the operation reaches, not at the pick or the set.
06The rigging arrangementEvery sling, shackle and accessory with its identity and rating, and the calculated force in each.
07The lift points and their design basisPadeye, trunnion or sling-around position, the design load, the route used, and the reference to the calculation.
08The ground or supporting structureOutrigger or track loads, mat arrangement, ground allowable with its provenance, and the check itself.
09The load path, as a drawingPlan and elevation showing the crane, the load, the swing arc and every clearance that matters.
10ClearancesOverhead services, adjacent structures, and the minimum approach distance to anything live, with a number.
11The people and their competencesAppointed person, supervisor, operator, slingers and signallers, named or role-named, with the qualification each holds.
12The exclusion zone and how it is enforcedA drawn boundary, the means of enforcing it, and who is standing on it.
13The sequence, step by stepNumbered steps a supervisor can read out, including the hold points where somebody has to confirm before the next step.
14The limits and abort criteriaWind speed, visibility, load angle, out-of-level, and what happens when one is reached. Written before the lift.
15The emergency arrangementsWhat happens if the load cannot be landed, if the crane cannot slew, or if someone is injured inside the zone.

Three of those repay attention because they are the ones that separate a plan from a form.

The provenance line. Every number gets one: where it came from and who owns it. "45 t, from weighbridge ticket 4471 dated 12 June" is a number a reviewer can accept or challenge. "45 t" is not.

The hold points. A sequence without hold points is a narrative. A sequence with them is a procedure, because it names the moments at which somebody is required to stop and confirm.

The abort criteria, written in advance. The whole value of writing them down is that they are decided by someone who is not under time pressure, in a room, before the crane is rigged.

The numbers the plan has to carry

Three chains: the load, the rigging and the ground. Most plans carry the first two and mention the third.

The load chain is the one every plan has, and the thing worth insisting on is that each factor appears as its own step with its own owner.

Each step has an owner. A plan that prints only the final number cannot be checked, because a reviewer cannot see which multiplication is the one they disagree with.

The rigging chain follows from that gross load: the share at each lift point, the angle factor on each leg, and a comparison against each accessory's rating and each lift point's design.

The ground chain is the one that goes missing, and the worked example is deliberately that one.

Crane Ground Bearing Pressure & Outrigger Pad Calculator · computed at page render

Revision B of the plan: the ground as first written

A 250 t class machine on 3.0 m mats over a yard slab taken at 400 kPa.

Worst outrigger loadFL at 90 degrees of slew	980kN
Matspread declared at 30 degrees	3.0 x 3.0 x 0.6m
Mat plan area	9.0m2
Area creditedspread reaches 0.35 m each side	1.94m2
Pressure on the ground	505kPa
Slab taken atno confirmation on file	400kPa
Float bearing on the mat	80.0%
Mat shear and punching	27.3%

Governing check: Pad bearing pressure on ground126.3% utilisationFail

Failing, and the plan is otherwise complete. This is the normal shape of the problem: the rigging was calculated properly, the chart was attached, and the ground was a sentence.

Open this example in the calculator

Now the plan does the thing a plan is for.

Crane Ground Bearing Pressure & Outrigger Pad Calculator · computed at page render

Revision C: two controls, and no more steel

The permitted slew arc is restricted to 45 degrees either side of the setting-down position, and the standing area is replaced by a designed working platform confirmed at 500 kPa. The mats are unchanged.

Worst outrigger loadnow FL at 45 degrees, because 90 is no longer permitted	910kN
Reduction from the slew restrictiona control, not a component	70kN
Area creditedunchanged: the same mats	1.94m2
Pressure on the groundagainst 505 kPa	469kPa
Platform confirmed attemporary works design, signed	500kPa
Ground bearing utilisation	93.8%

Governing check: Pad bearing pressure on ground93.8% utilisationPass

Passing. Note that neither change was structural. A restriction on the permitted slew arc and a confirmed platform value are both things a plan says, and both are inputs to the calculation. That is the argument for putting the calculation in the plan rather than beside it.

Open this example in the calculator

The controls in a lift plan are load cases. A permitted slew arc, a maximum wind speed, a minimum sling angle and a maximum out-of-level are not administrative text: each one bounds a variable the calculation depends on. Writing them separately from the calculation is how a plan comes to contain two different lifts.

The people, and what each one is actually for

Four roles, and the failure mode of each is different. Naming them by role is not bureaucracy; it is how the plan says who is allowed to stop the lift.

The person who plans it. Competent to plan lifting operations, and responsible for the plan being right, complete and communicated. In the UK framework this role is explicit; elsewhere it is often implicit, and implicit is where it goes wrong. The failure mode is a plan written by somebody without the authority to impose its controls.

The person who supervises it. Present, in charge, and the one who enforces the hold points and the abort criteria on the day. The failure mode is a supervisor who was not part of the planning and is discovering the sequence while it happens.

The operator. Responsible for the machine and entitled to refuse. The failure mode is an operator who has not seen the plan and is being directed by somebody who has.

The slingers and signallers. Responsible for the rigging and the communication. The failure mode is an unbriefed signaller in a blind lift, which is the specific combination that produces the worst outcomes on this list.

How to review one in twenty minutes

Read it in this order and the weaknesses surface fast. Reading it front to back is how a reviewer runs out of attention exactly where the calculations are.

Find the governing case first. Not the pick, not the set: the worst position the operation passes through. If the plan does not identify one, that is the finding.
Check the weight's provenance. Weighed, calculated, or from a data sheet. If it is "as advised", find out by whom.
Check the chart page against the configuration. Counterweight, boom, jib, outrigger extension, and that the page attached is the page for that combination. This mismatch is common and it is fast to check.
Check the duty at the governing radius, not at the pick. A lift that is 68 percent of chart at the pick and 94 percent at the set is a 94 percent lift.
Follow one force all the way down. Pick a single lift point and trace it: gross load, share, angle factor, accessory rating, lift point design, and into the structure. A plan that breaks anywhere in that chain breaks everywhere.
Go straight to the ground. Outrigger load, mat, credited area, pressure, allowable, and who confirmed the allowable. This is where a plan is thinnest.
Read the abort criteria. If they are absent or unmeasurable, the plan has no failure mode, which means it has one and has not written it down.
Check the drawing against the text. Plans get revised in one place and not the other. A swing arc on the drawing that does not match the slew restriction in the text is a real defect and it takes ten seconds to find.

Eight ways a lift plan fails review

None of these is an arithmetic error. Every one of them is something a reviewer cannot check.

1. Numbers with no provenance. A weight, a bearing value and a centre of gravity, each stated as a fact with no source. Nothing in the plan can be verified.

2. The governing case unidentified. The plan covers the pick and the set and says nothing about the worst position in between.

3. Controls separated from the calculation. A slew restriction in the text and a calculation that swept the full arc, or the reverse. The plan then describes two different lifts.

4. The ground as a sentence. "Ground conditions to be confirmed prior to the lift" is not a check. It is a hole with a note in it.

5. A chart page for a different configuration. Right machine, wrong counterweight or wrong outrigger extension. Common, and it can go either way.

6. Duty quoted at the wrong radius. Almost always the pick, which is almost never the governing one.

7. Abort criteria that cannot be measured. "Abort if conditions become unsafe" delegates the judgement to the person with the least time to make it.

8. No revision control. A plan without a revision number and a date on every page is a plan somebody will execute an old version of. Print the revision in the footer.

Common questions

What makes a lift a critical lift?: Consequence out of proportion to the operation, not weight. The usual triggers are a unique or long-lead load, people working under or near the path, live plant or services beneath it, two cranes sharing the load, any operation that turns or upends the load, working above roughly 75 to 80 percent of chart, a blind lift, and ground or a supporting structure whose capacity has not been proven. Any single one of those should push a lift into the critical category, and the plan should say which one did.
What has to be in a critical lift plan?: Fifteen things, and each number needs a provenance line. What is being lifted and from where to where; the weight and where it came from; the centre of gravity with its tolerance; the crane, its configuration and the specific chart page; the duty at the governing radius rather than at the pick; the rigging arrangement with every accessory rated; the lift points and their design basis; the ground or supporting structure with its check; the load path as a drawing; clearances; the people and their competences; the exclusion zone and how it is enforced; a numbered sequence with hold points; measurable limits and abort criteria; and the emergency arrangements.
Who writes and approves a lift plan?: A person competent to plan lifting operations, with the authority to impose the controls the plan contains. That authority matters more than the job title: a plan written by somebody who cannot enforce a slew restriction or a wind limit is a document rather than a control. The supervisor who will run the lift should be part of the planning rather than meeting the sequence for the first time on the day, and the operator should have seen the plan before being directed by somebody who has.
Why does the ground check belong in the lift plan?: Because the plan's controls are inputs to it. In this article's worked example the ground check fails at 126 percent as first written and passes at 94 after two changes, and neither change was structural: the permitted slew arc was restricted, which lowered the worst outrigger load from 980 kN to 910, and the standing area was replaced by a working platform confirmed at 500 kPa. Keeping the calculation somewhere other than the plan is how a plan comes to describe a different lift from the one that was checked.
How do I review a lift plan quickly?: In this order: find the governing case, check the weight's provenance, check the chart page matches the stated configuration, check the duty at the governing radius rather than at the pick, follow one force from the hook all the way into the structure, go straight to the ground check and find out who confirmed the allowable, read the abort criteria for whether they can be measured, and compare the drawing against the text. Reading front to back is how a reviewer runs out of attention exactly where the calculations are.

Sources

Every document below is linked at its publisher or regulator. Xarpis reproduces no standard text; where a clause is named, the identifier is given so you can find it in your own copy.

HSE lifting equipment guidanceLifting equipment at work: planning and organising lifting operations
UK Health and Safety Executive · free to read
The regulator's own plain-language account of what planning a lifting operation means in UK law: who is competent to plan it, what a plan has to address, and how it scales from a routine repetitive lift to a one-off complex one. Free, short, and the closest thing to an official answer to 'what has to be in a lift plan'.
LOLER 1998Lifting Operations and Lifting Equipment Regulations
UK Health and Safety Executive · free to read
The UK duty framework for lifting operations: planning by a competent person, supervision, and thorough examination of lifting equipment and accessories. Like OSHA's rules it governs the process, not the arithmetic.
29 CFR 1926 Subpart CCCranes and Derricks in Construction
US Occupational Safety and Health Administration · free to read
The whole US construction crane subpart, free in full: ground conditions, assembly and disassembly, power line clearance, operator qualification, signals, inspection and multiple-crane lifts. The index page, because the duty a reader needs is usually two sections away from the one they searched for.
29 CFR 1926.1402Ground conditions (Cranes and Derricks in Construction)
US Occupational Safety and Health Administration · free to read
Requires ground supporting a crane to be firm, drained and graded sufficiently for the manufacturer's specifications, and places the duty to prepare it, and to disclose voids and buried services, on the controlling entity. It states a duty; it prescribes no calculation.
ASME B30.5Mobile and Locomotive Cranes
ASME · paid document
Construction, installation, operation, inspection and maintenance of mobile cranes in the US, including load rating and the requirement to operate within the manufacturer's chart. It governs the machine; the ground it stands on is 29 CFR 1926.1402 and the calculation is yours.

Run the check properly

Reading about a calculation is not the same as being able to hand one over. These tools produce the traceable record.

Spreader Beam Design Calculator Lifting Lug Calculator Vessel Upending & Tailing Lift Calculator

Something here wrong, or thinner than it should be? Tell us which paragraph and it gets rewritten. Articles carry the date they were last revised for exactly this reason.