ISO/TR 7015:2023

TECHNICAL ISO/TR
REPORT 7015
First edition
2023-04
Ergonomics — The application of
ISO/TR 12295, ISO 11226, the ISO
11228 series and ISO/TR 23476
in the construction sector (civil
construction)
Ergonomie — Application de l'ISO/TR 12295, de l'ISO 11226,
de la série ISO 11228 et de l'ISO/TR 23476 dans le secteur de la
construction (construction civile)
Reference number
© ISO 2023
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ii
Contents Page
Foreword .v
Introduction . vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 General outline of work processes in an annual multi-task analysis in civil
construction . 1
4.1 General structure of a multi-task analysis . 1
4.2 Study of tasks distribution over the year on groups of workers who are
homogeneous in terms of risk exposure . 3
4.2.1 General . 3
4.2.2 Macrocycle duration . 5
4.2.3 Phase and task identification . 6
4.2.4 Identification of the different homogeneous groups . 10
5 First levels: pre-mapping of danger and discomfort through key questions and
quick assessment .12
5.1 Foreword.12
5.2 The pre-mapping model . 13
6 Analytical study of work processes in annual multi-task analysis: description of a
typical working day for each month and quantitative task distribution over the year .15
6.1 General . 15
6.2 Phase A – Description of a typical working day . 15
6.3 Phase B – Estimation of total number of hours worked every month of the year . 17
6.4 Phase C – Assignment of tasks to a homogeneous group (or individual worker) and
calculation of proportional tasks duration in each individual month . 17
7 Annual multi-task risk assessment of biomechanical overload for the upper limbs .20
7.1 General . 20
7.2 Phase A – Analysis of each individual task using the OCRA checklist to calculate
the intrinsic risk score and prepare the tasks basic risk evaluation for each crop .20
7.3 Phase B – Application of mathematical models and preliminary preparation of
artificial working day representative of the whole year and of every month of the
same year. 20
8 Annual multi-task risk assessment for working postures .22
8.1 The meaning of postural tolerance . 22
8.2 Analysing the tolerability of working postures for the spine when performing
manual lifting tasks, and for the upper limbs when performing repetitive
movements and manual lifting: specific International Standards .23
8.3 Analysing spinal working postures without manual load lifting and lower limb
postures (primarily static) .23
8.4 The TACOS method: contents and criteria for back and lower limb posture analysis .25
8.5 Posture analysis of a multi-task job performed on a full-time or part-time basis
with yearly job rotation . 26
9 Annual multi-task risk assessment of manual material handling (MMH) and
carrying .32
10 Annual multi-task risk assessment of pushing and pulling .35
11 Manual material carrying (MMC) risk assessment .37
12 Conclusions .38
iii
Annex A (informative) Initial identification and preliminary assessment (pre-mapping)
of potential risks: criteria and presentation of a specific simple tool that allows its
application .40
Annex B (informative) Criteria and mathematical models for analysing exposure to
biomechanical overload in multitask jobs featuring complex macro-cycles (e.g.
weekly, monthly, annual turnover) .70
Annex C (informative) Criteria to evaluate working postures of the spine and lower limbs
using the TACOS strategy in daily or other macro-cycle multi-task analysis: brief
presentation .98
Bibliography .117
iv
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www.iso.org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to
the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see
www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 159, Ergonomics, Subcommittee SC 3,
Anthropometry and biomechanics.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.
v
Introduction
Construction is one of the biggest working sectors in the world. The sector includes an immense
diversity of skill sets and categories of workers. In addition, the size, structure and market of
construction companies can also be extremely variable. The sector employs on average between 5 %
to 10 % of the workforce in most countries, indicating that construction is a significant component of
the global economy and is one of the largest employers in the world. Globally, musculoskeletal disorders
are the major cause of work-related illnesses, accounting for more than 33 % of all occupational
[49]
diseases, with the prevalence becoming 65 % for construction workers. There are also indirect
socio-economic implications due to job loss, absenteeism, health costs and even worker hospitalization.
[29]
There is no doubt that the prevention of work-related musculoskeletal disorders (WMSDs) can
significantly contribute to reduce economic and social impact. Increasing attention is being drawn to
the application of practical actions in construction settings to help reduce work-related accidents and
illness and WMSDs in particular. ISO 11226, the ISO 11228 series and, more recently, ISO/TR 12295 and
ISO/TR 23476 are useful for this specific scope.
Experiences in the application of these documents have been acquired in different parts of the world,
but rarely in construction. This document extends the scope and methods included in existing standards
to all the different construction, although the application experiences presented in this document are
mainly based on the civil construction sector. Special attention is devoted to rendering this document
accessible also to non-experts. Reference is made to easily applicable, non-commercial online tools
(simple tools in spreadsheets) that can be useful for the purposes of this document, making possible the
application of the criteria provided here and therefore the real numerical estimate of the biomechanical
overload risks.
The ISO 11228 series, ISO 11226, ISO/TR 12295 and ISO/TR 23476 establish ergonomic recommendations
for different manual handling tasks, repetitive movements and working postures. All their parts apply
to occupational and non-occupational activities. The documents provide information for designers,
employers, employees and others involved in work, job and product design, such as occupational health
and safety professionals.
The ISO 11228 series consists of the following parts, under the general title Ergonomics — Manual
handling:
— Part 1: Lifting, lowering and carrying;
— Part 2: Pushing and pulling;
— Part 3: Handling of low loads at high frequency.
ISO 11226 provides recommended limits for static working postures with no or minimal external force
exertion, while taking into account body angles and duration.
ISO/TR 12295 serves as an application guide of the ISO 11228 series and ISO 11226. It offers a simple
risk assessment methodology for small and medium enterprises and for non-professional active.
This document is intended to be used alongside ISO/TR 12295, ISO 11226, the ISO 11228 series and
ISO/TR 23476, also in the construction sector, where the risk from biomechanical work overload from
repetitive movements, from manual handling of loads, from towing and pushing carts and awkward
postures is universally present.
[22]
The OCRA checklist method, in its multi-day cycle risk assessment version, is currently the only
risk assessment method available in literature capable of offering criteria and application experiences
to address multitask analysis (supported by a specific simple tool in the form of free download
spreadsheets for final risk calculation).
ISO/TR 12295 had already adopted this multitask method of exposure analysis.
After all, the development of a method capable of predicting the appearance of pathologies (real risk
assessment method) can be optimized only after years of use and improvement. The development of
vi
a new TR which, offering evaluation solutions for biomechanical overload study in construction, can
stimulate many more valid epidemiological studies in the future, is therefore desirable. The concept of
doing nothing, while waiting for sufficient and perfect published methods, means not doing prevention.
The National Institute for Occupational Safety and Health (NIOSH) itself, due to the formula for
calculating the lifting index (LI), changed the maximum limit value of its first formula several times
over the years, through years of application experience. Recently the NIOSH added the formula for
calculating the variable lifting index (VLI) for the evaluation of manual lifting tasks of complex loads,
[21],[67]
with many different weights and geometries. The gained experience in this type of analysis was
introduced in ISO/TR 12295 and ISO 11228-1.
For the study of working postures it is important to point out the new time-based assessment
[25]
computerized strategy (TACOS) for posture, which adds to all the experience gained from the
RULA and REBA methods and from ISO 11226, a more adequate timing assessment (therefore not only
qualitative studies of work postures, but also studies of their real duration).
The mathematical criterion for the extension of the calculation of any risk factors for the study of
biomechanical overload, not only for the working day cycle but also for cycles different in duration (e.g.
annual cultivation cycles), was also discussed within a specifically activated writing group of experts
for the preparation of this document. The transition is indispensable for the extension of the evaluation
models already present in the specific International Standards (all used in this document) to the risk
evaluation in multitask exposition with annual turnover needed for risk studies in construction (see
Annex B).
Any other risk assessment methods that include a multitask analysis procedure can adopt the criteria
here proposed, extending multitask annual exposure risk study, for instance to:
— repetitive movements (e.g. strain index, method present in ISO 11228-3);
— manual handling of loads (NIOSH formula in ISO 11228-1);
— application of ISO 11226, the ISO 11228 series and ISO/TR 12295 in the agricultural sector
(ISO/TR 23476).
vii
TECHNICAL REPORT ISO/TR 7015:2023(E)
Ergonomics — The application of ISO/TR 12295, ISO
11226, the ISO 11228 series and ISO/TR 23476 in the
construction sector (civil construction)
1 Scope
This document is intended to be used alongside ISO/TR 12295, ISO 11226, the ISO 11228 series and
ISO/TR 23476 in the construction sector.
This document (although the examples shown refer only to the civil construction sector) gives
information on how existing standards can be used in a global sector, such as construction. Where
biomechanical overload is a relevant aspect, albeit with different characteristics, work-related
musculoskeletal disorders (WMSDs) are common and specific preventive actions are needed.
This document is intended to:
1) define the user(s) and fields for its application (including non-experts in ergonomics);
2) provide examples of procedures for hazard identification, risk estimation or evaluation and risk
reduction in different agricultural settings, through:
— more synthetic procedural schemes (main test);
— more analytical explanations of the procedures, through mathematical models and application
examples, and with the use of specific free simple tools in Annexes A, B and C.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
No terms and definitions are listed in this document.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
4 General outline of work processes in an annual multi-task analysis in civil
construction
4.1 General structure of a multi-task analysis
Specifically, this document provides additional information to aid the user in the selection and use of
the appropriate standards. Depending upon whether specific risks are present, it is intended to help the
user to decide which standards to apply. It will include three levels of approach (Figure 1):
— First level: the participatory approach for pre-mapping of danger and discomfort provides all users,
particularly those who are not experts in ergonomics, with criteria and procedures to identify
situations in which they can apply the ISO 11228 series, ISO 11226 and ISO/TR 12295 as well as in
agricultural settings (ISO/TR 23476): key-enter and key-questions level. Only in the early analytical
stage is the opportunity offered to map, even if only using subjective data obtained by interviewing
the workers (through the identification of groups of workers, homogeneous for exposure to
occupational risks), all the occupational hazards and not just the risk of biomechanical overload.
— Second level: provides a quick assessment method (according to the criteria provided in
ISO/TR 12295 and in ISO/TR 23476) for easily recognizing activities that are definitely acceptable or
definitely critical. If an activity is neither definitely acceptable nor definitely critical, it is necessary
to complete a detailed risk-assessment as set out in the standards, continuing with the necessary
subsequent preventive actions.
— Third level: refer to detailed methods for risk assessment set out in the relevant standards when the
quick assessment method shows that the activity risk falls between the two exposure conditions
(definitely acceptable or definitely critical).
These approaches and scopes are illustrated in the flowchart in Figure 1 and are described in the main
text of ISO/TR 12295.
At first the user is required to answer a short series of practical questions present in the first and second
level. It is emphasized that the quick-assessment method is best implemented using a participatory
approach involving workers in the enterprise (homogeneous groups of workers).
This involvement is deemed to be essential for effectively setting priorities for dealing with the different
hazard and risk conditions and, where necessary, identifying effective risk reduction measures.
In construction, as well as in agriculture evaluation, it can be possible to limit the study to the first and
second levels, obtaining sufficient data about occupational risk priorities.
The analytical risk assessment approach (third level) provides all users, especially those experienced
in ergonomics, or familiar with the ISO 11228 series, with details and criteria for applying the risk
assessment methods proposed in the original standards also to construction.
This analytical risk assessment approach is fully consistent with the methods proposed in the standards
and does not introduce any changes in the criteria (mathematical model) for risk calculations, defined in
the existing standards (as well expressed in ISO/TR 12295) but only adapts the proposed methodology
to the risk assessment in construction
The proposed additional analyses aim to facilitate the use of the actual standards, making it possible
to extend them to risk assessment in agriculture (ISO/TR 23476) and now, with many methodological
analogies, also to construction (Annexes A, B and C present application examples in civil construction).
Figure 1 — Different risk assessment levels according to ISO/TR 12295 for biomechanical
overload estimation
4.2 Study of tasks distribution over the year on groups of workers who are
homogeneous in terms of risk exposure
4.2.1 General
Studying the organization of work in the construction sector, the basis for comprehensively addressing
the study of exposure risk is certainly very complex. In this work, while evaluation criteria and
techniques can be extended to all sectors that characterize construction, the application examples
presented here refer to the civil construction sector.
Table 1 summarizes the main macro-phases that characterize the civil construction sector, which can
be summarized even more briefly in eight main construction phases: ground preparation, excavation
of foundations and their reinforcement; construction of vertical and horizontal support structures
(pillars and support beams); flooring construction; construction of internal and external walls; re-
embossing and finishing of internal and external walls and floors with mortar; external coatings and
internal whitewashing; laying pipes for electrical systems; roof construction.
The study of the finishes of civil constructions with the installation of all the necessary systems, such
as plumbing, electrical, heating or the laying of interior coverings (wood tiles), has been deliberately
neglected, since each of these works presents its own specific risk professional.
Table 1 — Main macro-phases and work phases present in the civil construction sector
Macro-phases Phases
supplies cranes
— pallets trucks
— wheelbarrows
work tools — jack hammer
— planer
— drill
— float
— hammer
— trowel
— screwdriver
— crowbar
— line level
— spade
foundation — initial prepara-
excavation and tion of the soil
armour
— delimitation
of building site
-excavation and
drilling
— land compac-
tion-position-
ing foundation
armour, beams,
pipes
building ver- — preparation of
tical support wooden panels
supplies
construction and
assembly shapes
and frames in
wood for pillars
and beams
building hori- — laying support
zontal sup- material
ports: floors/
floor/ceiling as-
ceiling
sembly
piping installation
— concrete dis-
tribution-disas-
sembly of wooden
structure
wall con- external and
struction with internal wall
bricks; electri- construction with
cal installa- bricks
tions
— electrical in-
stallations
TTabablele 1 1 ((ccoonnttiinnueuedd))
Macro-phases Phases
mortar ap- facade coating
plication and – external and
finishing internal wall,
beams and pillar,
window, doors,
ceiling with
mortar
— finishing; floor
levelling mortar
-waterproofing
external and — different exter-
internal coat- nal coating
ing (painting
— internal coat-
or other)
ing (painting or
other
roof assembly roof assembly
-structure
In a setting such as construction, before starting a risk analysis it is necessary to define a set of
procedures and criteria for estimating risk in complex situations where workers perform multiple
tasks, variously distributed in qualitative and quantitative terms over the year (annual cycle).
The general risk evaluation process entails a certain number of steps, beginning with:
a) identification of the macrocycle of the many different tasks;
b) analysis of construction site to identify tasks performed within the period and obtain a qualitative
definition of the work during each month of the year;
c) identification of one or more homogeneous groups.
4.2.2 Macrocycle duration
Task rotation is when a worker alternates between two or more tasks during a certain period of time;
this situation occurs quite often in modern work organizations and, if properly designed, can represent
one of the most effective strategies for reducing the risk of biomechanical overload.
In situations, such as in construction, where the worker has to perform a large number of tasks and
the tasks can be distributed asymmetrically over the shift, risk assessments can become extremely
complex. This is why it is necessary to carry out a thorough preliminary study of how the work is
organized. At any rate, the risk analysis process involves different steps, listed further on.
The first step consists in defining the time required to complete the task rotation schedule; this is the
macro-cycle time, which can be daily, weekly, monthly or yearly.
The types of macrocycles durations are infinite, but if there are no simplification criteria that allow the
risk to be estimated, every risk assessment stops and nothing is done (the excuse being that the mission
is impossible).
The modal macro-cycle periods appear to be, at least in the sectors of agriculture, building construction
and services, accurately representative of job cycles. In civil construction, task rotations are typically
annual, but one can use annual cycles even when multiple cycles of fewer months in each year are
repeated identically. In the construction sector there is generally a yearly cycle for large construction
sites, but a monthly cycle (modal) is more frequent in smaller-scale constructions and civil renovation
projects. In other sectors (e.g. logistics for retail chains, cleaning services, food preparation facilities),
the most common rotation scenario is monthly, while in yet other situations (e.g. supermarkets) tasks
can be rotated on a weekly or, occasionally, a monthly basis.
In summary, some practical options are provided here for using the predefined macro-cycle (weekly,
monthly, yearly), thus certainly simplifying subsequent evaluations:
— If several identical sub-macro-cycles are repeated over the year, the annual macro-cycle can be
used.
— If several identical sub-macro-cycles (e.g. week, fortnight) are repeated within the month and if the
following months are similarly repeated, the monthly macro-cycle can be used.
Whichever macro-cycle duration is chosen, the criteria and procedures for dealing with the
biomechanical overload risk analysis are the same. Given the extreme activity variability, the procedure
is, however, to identify and evaluate representative modal scenarios.
4.2.3 Phase and task identification
It is not simple to identify farming tasks, which can be very numerous and performed by different
workers or groups of workers. At the outset, therefore, it is necessary to:
a) identify the specific worksite (e.g. civil and road construction sites, demolitions, renovations);
b) break down the worksite activities into phases; all relevant tasks must be identified inside each
phase.
The same activity can be carried out in several different ways; each operating method is intended to
be viewed as a separate task and listed accordingly (e.g. plastering with short trowel, with spoon, with
projector, with long level).
It is important to note that all the tasks performed at the farm over the year have to be evidenced,
including preparing the soil, applying fertilizers and pesticides and other seemingly ancillary activities,
regardless of who performs them.
As it is so inherently difficult to identify phases and tasks in the construction sector, a kind of universal
civil construction system has been developed that will enable even beginners to conduct a preliminary
organizational analysis. This universal structure could also be extended to the study of other
construction sectors, but additions will certainly be necessary to make it more specific.
It consists of a list of phases, including those ancillary to the actual construction of the building, for
example all material transportation mechanized or not, demarcation of the construction in the site,
excavation with drilling equipment preparation of wooden panels or removal of wood shapes from the
foundation, see Table 2.
Table 2 — Principal tasks characterizing a universal civil construction system
Macro-phases Phases Tasks
common tasks at mechanized crane operation - street level
all stages
material transportation
operation with high cab crane
(aa)
transport with electric pallet
transport with manual pallet
transport with 4-wheel cart
transport with 2-wheel cart
transport with mason wheelbarrow
TTabablele 2 2 ((ccoonnttiinnueuedd))
Macro-phases Phases Tasks
manual transportation: manual transportation weight kg = inf. 3
weight per person.
manual transport weight kg = 4 to 7
(ag)
manual transportation weight kg = 8 to11
manual transportation weight kg = 12 to15
manual transportation weight kg = 16 to 25
manual transportation weight kg = 26 to40
manual transport weight kg = 4 to7 (head or shoulder)
manual transport weight kg = 8 to11 (head or shoulder)
manual transport weight kg = 12to 15 (head or shoulder)
manual transport weight kg = 16 to25 (head or shoulder)
manual transportation weight kg = 26 to40 (head or shoulder)
manual transport weight kg = sup 40 (head or shoulder)
work tool working tools drill
pneumatic hammer
electric screwdriver
electric cutter
milling machine
hammer
cutter
circular saws
hand cutting saw
alternative saws
screwdriver
manual pliers and other like it
foundation exca- delimitation of building marking of reference points
vation site (plant) with refer-
ence points
manual fixing of the wooden props to the ground
fixing side boards in the jig with nails
plumb line positioning to delimit the foundations
initial preparation of the excavation of land with tractors
soil
levelling/ backfilling ground with tractors
excavation with drilling positioning drilling equipment
equipment
check excavation with rotary drilling tool
manual removal of land near the machine drilling
positioning foundation positioning of the armour irons inside the holes of the founda-
armour tion
positioning of foundation construction of connection beams with wood and concrete
beams castings
homogenization of concrete with vibration equipment
removal of wood manual removal of wood shapes from foundation beams
manual excavation for manual excavation for passage of underground pipe
pipes
land compaction land compaction with specific vibrating tool
TTabablele 2 2 ((ccoonnttiinnueuedd))
Macro-phases Phases Tasks
support supplies preparation of wooden receiving and sending spare parts for storage and cutting areas
panels (shapes)
align, cut, adjust parts
cut panels according to the project
number of panels according to the project
storage of panels in a clean area
preparation of the pillar forms
preparation of beam shapes
prep. external wooden panels with cutter
waterproofing wood shapes
wood panel (shape) in- angular anchorage support for wooden pillars
stallation
waterproofing application in pillar forms
installation of wood shapes on the floor
installation of internal forms
installation of external security armour
construction wood placement of armour in the pillar
shapes for pillars (form-
assembly of the pillars wooden form
work)
pillar filling with concrete
homogenization of concrete with vibrator
removal of wood forms of pillar
beam assembly placement of armour within the shape of beams
assembly of beam shapes with wooden form
pillar filling with concrete
homogenization of concrete with vibrator
removal of wooden beam shapes
building floors/ laying support material placement of punches
ceiling
placement of cross beams
placement of panels, prefabricated beams and special bricks
floor/ceiling assembly prefabricated slab positioning
(pre-manufactured)
transport and positioning of the electro-welded network
fixing of the electro-welded network
piping installation preparation of cable and tube passage - (electric)
transportation of pipes and cables
pipe cutting and insertion
fixing the tube in the electric passage box
concrete distribution automatic pump driver operator of concrete launch
filling slab with concrete using bucket
filling slab with concrete using pump
homogenization with vibrator
wet concrete with water barrel
spreading concrete with shovel
concrete levelling with metallic ruler
concrete levelling with laser level
TTabablele 2 2 ((ccoonnttiinnueuedd))
Macro-phases Phases Tasks
disassembly of the struc- shoring removal
ture
formwork removal with crowbar
wall construction external and internal preparation of cement mortar
with bricks wall construction with
lift brick wall 0 kg to 3 kg (low-medium-high)
bricks
lift brick wall 4 kg to7 kg (low-medium-high)
lift brick wall 8 kg to11 kg (low-medium-high)
lift brick wall 12 kg to 15 kg (low-medium-high)
lift brick wall 16 kg to 25 kg (low-medium-high)
lift brick wall sup 25 kg (low-medium-high)
using plumb-line in the construction of wall
using bubble level tool
side jamb installation
installation jamb to window
mortar application facade coating - external cement mortar application with projector
and finishing
external coating and finishing with trowels and floats
smoothing with rod
cement mortar application - external - with scaffolding
internal wall, beams and internal wall covering with projector
pillar, window, doors,
external coating and finishing with trowels and floats
ceiling mortar
smoothing with rod
spreading running pasta (thin) with roller
finishing smoothing with spoon
smoothing with rod
small defects closure with trowel
floor levelling mortar spreading and flattening cement mortar with hand tool
spreading adhesive mortar with toothed spatula
placement of ceramic on floor
performing joint
waterproofing waterproofing waterproofing with liquid blanket
electrical installa- electrical installations - electrical installation: piping
tions
electrical cable installations in the slab
external coating external coating adhesive application (special mortar)
laying the coating on the adhesive
other other external coating application
internal coating internal painting application of the wall putty
(painting)
drywall sanding wall putty
application of the sealant or preparatory base
roller paint application
brush paint application
roof assembly roof assembly -structure structure assembly
manual parts handling (see manual transportation)
cover assembly (electric screwdriver)
4.2.4 Identification of the different homogeneous groups
The next step is to assign tasks to an individual worker or group of workers exposed to the same risk,
to identify homogeneous groups. Since the focus of the analysis is the exposure of workers to a set of
conditions determined by the tasks they are assigned to perform, it is first necessary to identify which
homogeneous group of workers are present that need to be examined.
The homogeneous group of workers for risk exposure (as groups of workers homogeneous for working
risks are being defined, not groups of people homogeneous for other factors, such as weight, age,
culture or gender) is the group of workers that performs the same tasks, in the same workplace and
with similar durations (or time patterns) during the selected period (macro-cycle).
Note that a homogeneous group can sometimes be made up of just one person, if no other workers
perform the same tasks qualitatively and quantitatively.
Moreover, if two groups of workers perform the same tasks in the same workplaces but with different
durations or time patterns (e.g. one group works full-time and the other works part-time) the two
groups must be analysed separately.
The homogeneous groups that can be identified in a construction site can be very numerous: by way
of example, in Tables 3 and Figure 2, three groups are presented, different in terms of tasks performed
and duration. Table 3 reports the distribution in % of tasks duration in different months of the year in
different homogeneous groups; Table 4 describes the representation of task duration in % in different
months of the year where grey area indicates when 100 % of the constant is exceeded.
The assignment of the tasks to a homogeneous group (or individual worker) even just from the
qualitative standpoint (or semi-quantitative as here), is not difficult but it is absolutely essential before
conducting the first levels of risk evaluation (key questions and quick assessment level).
To determine the real risk exposure (risk assessment level) it is necessary to study a quantitative
description of all active tasks.
Only after this organizational analysis can the different risk levels be assessed in terms of repetitive
movements, manual load handling, awkward postures and pushing-pulling.
Table 3 — Distribution in % of task duration in different months of the year in different
homogeneous groups
Breakdown of the task duration for each month of the year
All the repetitive tasks
Homogeneous group no.1: distribution of concrete (floors, columns, beams)
hours worked per month 220 200 220 220 200 195 220
floor filling with concrete 15 % 15 % 15 % 15 % 15 % 15 % 15 %
concrete vibrator homogenization 5 % 5 % 5 % 5 % 5 % 5 % 5 %
filling with concrete 15 % 15 % 15 % 15 % 15 % 15 % 15 %
homogenization with vibrator 20 mm
5 % 5 % 5 % 5 % 5 % 5 % 5 %
- 40 mm
pump operator guide launches concrete 10 % 10 % 10 % 10 % 10 % 10 % 10 %
emptying concrete with cement mixer 10 % 10 % 10 % 10 % 10 % 10 % 10 %
spreading concrete with shovel 10 % 10 % 10 % 10 % 10 % 10 % 10 %
homogenization 3 % 3 % 3 % 3 % 3 % 3 % 3 %
insured vibrator extension 1 % 1 % 1 % 1 % 1 % 1 % 1 %
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
TTabablele 3 3 ((ccoonnttiinnueuedd))
filling slab with pumped concrete 10 % 10 % 10 % 10 % 10 % 10 % 10 %
concrete spreading with hoe 10 % 10 % 10 % 10 % 10 % 10 % 10 %
concrete level with metal ruler 5 % 5 % 5 % 5 % 5 % 5 % 5 %
levelling with laser (reinforced con-
1 % 1 % 1 % 1 % 1 % 1 % 1 %
crete)
100 % 100 % 100 % 100 % 100 % 100 % 100 %
Homogeneous group no.2: walls construction
hours worked per month 220 200 200 190 195 200 200 200 200 200
control crane 5 % 5 % 5 % 5 % 5 % 5 % 5 % 5 % 5 % 5 %
manual pallet transport (strong force) 5 % 5 % 5 % 5 % 5 % 5 % 5 % 5 % 5 % 5 %
transport with wheelbarrow (mod-
5 % 5 % 5 % 5 % 5 % 5 % 5 % 5 % 5 % 5 %
erate force)
transport with wheelbarrow (strong
5 % 5 % 5 % 5 % 5 % 5 % 5 % 5 % 5 % 5 %
force)
preparation to block discharge 10 % 10 % 10 % 10 % 10 % 10 % 10 % 10 % 10 % 10 %
mortar preparation 10 % 10 % 10 % 10 % 10 % 10 % 10 % 10 % 10 % 10 %
lift wall brick inf 3 kg 10 % 10 % 10 % 10 % 10 % 10 % 10 % 10 % 10 % 10 %
lift wall 4 kg to 7 kg (low - medium
15 % 15 % 15 % 15 % 15 % 15 % 15 % 15 % 15 % 15 %
- high)
lift wall brick 8 kg to 11 kg (low-me-
15 % 15 % 15 % 15 % 15 % 15 % 15 % 15 % 15 % 15 %
dium-high)
use plumb 10 % 10 % 10 % 10 % 10 % 10 % 10 % 10 % 10 % 10 %
level use 10 % 10 % 10 % 10 % 10 % 10 % 10 % 10 % 10 % 10 %
100 % 100 % 100 % 100 % 100 % 100 % 100 % 100 % 100 % 100 %
Homogeneous group no.3: preparation internal wall for painting
hours worked per month   220 220 220 220 200 200
transport weight 16 kg to 25 kg   5 % 5 % 5 % 5 % 5 % 5 %
spread fine mortar with a roller   10 % 10 % 10 % 10 % 10 % 10 %
fine mortar sanding   10 % 10 % 10 % 10 % 10 % 10 %
finishing with floats (in instable po-
15 % 15 % 15 % 15 % 15 % 15 %
sition)
coating with fine mortar with floats
15 % 15 % 15 % 15 % 15 % 15 %
(in instable position) -
fine mortar coating with projector   15 % 15 % 15 % 15 % 15 % 15 %
coating with fine mortar with floats   15 % 15 % 15 % 15 % 15 % 15 %
finishing fine mortar with floats   15 % 15 % 15 % 15 % 15 % 15 %
0 % 0 % 0 % 0 % 0 % 0 % 100 % 100 % 100 % 100 % 100 % 100 %
a) Homogeneous group no.1: distribution of concrete (floors, columns, beams)
b) Homogeneous group no.2: walls construction
c) Homogeneous group no.3: preparation internal wall for painting
NOTE Grey area indicates when 100 % of the constant is exceeded.
Figure 2 — Representation of task duration in % in different months of the year where grey
area indicates when 100 % of the constant is exceeded
5 First levels: pre-mapping of danger and discomfort through key questions and
quick assessment
5.1 Foreword
One of the lat
...