Snook and Ciriello method
Snook and Ciriello method is used to assess the risk in relation to flat displacement, towing and loads thrust, as stated in ISO 11228-2.
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Behind this method there are psychophysical studies based on stress-effort conducted by Snook and Ciriello.
These studies start from overall movement breakdown in elementary actions such as:
The towing or thrust Index or flat displacement sums up the risk factor and it is assessed by comparing the strain recommended limit with that actually handled by measuring it with the force gauge, which is able to check the force applied and the peak. The higher the ratio, the greater is the risk factor.
The results of these studies are resumed in so-called "psychophysical tables" which provide important information on the capacity and limitations of workers concerning manual handling of loads (in a general sense, including towing, thrusting and transport actions).
For each type of action there are limit values of the reference weight (displacement actions) or the force exercised (in thrusting or towing actions), respectively, in the initial phase (peak force) and in action maintenance (maintenance force).
In the tables below there are "perfect" values respectively for the actions of thrusting, towing and flat displacement, divided for populations of healthy adults, males and females. The use of data showed in tables is very simple: it comes to identifying the situation that reflects better the real working situation examined. Decide whether the subject is male or female and extrapolate the recommended value (weight or force). Compare this value with the weight or force actually developed (measured with a certified force gauge). The risk index is obtained by the ratio of weight (force) actually handled in the specific work situation and weight (force) recommended for that action (see table 4).
Snook and Ciriello - thrusting actions – Tab. 1
Maximum starting forces (FI) and maintenance forces (FM), expressed in kilograms (Kg), recommended for working healthy adults, according to: sex, displacement distance, action frequency, height of the hands from the ground.
|
Snook and Ciriello – thrusting actions - MALES |
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|
DISTANCE |
2 metres |
7,5 metres |
15 metres |
60 metres |
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|
Action every: |
6s |
12s |
1m |
5m |
30m |
8h |
15s |
22s |
1m |
5m |
30m |
8h |
25s |
35s |
1m |
5m |
30m |
8h |
2m |
5m |
30m |
8h |
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|
Height of hands |
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|
145cm |
F I |
20 |
22 |
25 |
26 |
26 |
31 |
14 |
16 |
21 |
22 |
22 |
26 |
16 |
18 |
19 |
20 |
21 |
25 |
12 |
14 |
14 |
18 |
||||||
|
FM |
10 |
13 |
15 |
18 |
18 |
22 |
8 |
9 |
13 |
15 |
16 |
18 |
8 |
9 |
11 |
13 |
14 |
16 |
7 |
8 |
9 |
11 |
|||||||
|
95cm |
F I |
21 |
24 |
26 |
28 |
28 |
34 |
16 |
18 |
23 |
25 |
25 |
30 |
18 |
21 |
22 |
23 |
24 |
28 |
14 |
16 |
16 |
20 |
||||||
|
FM |
10 |
13 |
16 |
19 |
19 |
23 |
8 |
10 |
13 |
15 |
15 |
18 |
8 |
10 |
11 |
13 |
13 |
16 |
7 |
8 |
9 |
11 |
|||||||
|
65cm |
F I |
19 |
22 |
24 |
25 |
26 |
31 |
13 |
14 |
20 |
21 |
21 |
26 |
15 |
17 |
19 |
20 |
20 |
24 |
12 |
14 |
14 |
17 |
||||||
|
FM |
10 |
13 |
16 |
18 |
19 |
23 |
8 |
10 |
12 |
14 |
15 |
18 |
8 |
10 |
11 |
12 |
13 |
15 |
7 |
8 |
9 |
10 |
|||||||
|
Snook and Ciriello – thrusting actions - FEMALES |
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|
DISTANCE |
2 metres |
7,5 metres |
15 metres |
60 metres |
|||||||||||||||||||||||||
|
Action every: |
6s |
12s |
1m |
5m |
30m |
8h |
15s |
22s |
1m |
5m |
30m |
8h |
25s |
35s |
1m |
5m |
30m |
8h |
2m |
5m |
30m |
8h |
|||||||
|
Height of hands |
|||||||||||||||||||||||||||||
|
145cm |
F I |
14 |
15 |
17 |
20 |
21 |
22 |
15 |
16 |
16 |
18 |
19 |
20 |
12 |
14 |
14 |
15 |
16 |
17 |
12 |
13 |
14 |
15 |
||||||
|
FM |
6 |
8 |
10 |
11 |
12 |
14 |
6 |
7 |
7 |
8 |
9 |
11 |
5 |
6 |
6 |
7 |
7 |
9 |
4 |
4 |
4 |
6 |
|||||||
|
95cm |
F I |
14 |
15 |
17 |
20 |
21 |
22 |
14 |
15 |
16 |
19 |
19 |
21 |
11 |
13 |
14 |
16 |
16 |
17 |
12 |
13 |
14 |
16 |
||||||
|
FM |
6 |
7 |
9 |
10 |
11 |
13 |
6 |
7 |
8 |
9 |
9 |
11 |
5 |
6 |
6 |
7 |
8 |
10 |
4 |
4 |
5 |
6 |
|||||||
|
65cm |
F I |
11 |
12 |
14 |
16 |
17 |
16 |
11 |
12 |
14 |
16 |
16 |
17 |
9 |
11 |
12 |
13 |
14 |
15 |
10 |
11 |
12 |
13 |
||||||
|
FM |
5 |
6 |
8 |
9 |
9 |
12 |
6 |
7 |
7 |
8 |
9 |
11 |
5 |
6 |
6 |
7 |
7 |
9 |
4 |
4 |
4 |
6 |
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Snook and Ciriello – towing actions – Tab. 2
Maximum starting forces (FI) and maintenance forces (FM), expressed in kilograms (Kg), recommended for working healthy adults, according to: sex, displacement distance, action frequency, height of the hands from the ground.
|
Snook and Ciriello – towing actions - MALES |
|||||||||||||||||||||||
|
DISTANCE |
2 metres |
7,5 metres |
15 metres |
60 metres |
|||||||||||||||||||
|
Action every: |
6s |
12s |
1m |
5m |
30m |
8h |
15s |
22s |
1m |
5m |
30m |
8h |
25s |
35s |
1m |
5m |
30m |
8h |
2m |
5m |
30m |
8h |
|
|
Height of hands |
|||||||||||||||||||||||
|
135cm |
F I |
14 |
16 |
18 |
19 |
19 |
23 |
11 |
13 |
16 |
17 |
18 |
21 |
13 |
15 |
15 |
16 |
17 |
20 |
10 |
11 |
11 |
14 |
|
FM |
8 |
10 |
12 |
15 |
15 |
16 |
6 |
8 |
10 |
12 |
12 |
15 |
7 |
8 |
9 |
10 |
11 |
13 |
6 |
6 |
7 |
9 |
|
|
90cm |
F I |
19 |
22 |
25 |
27 |
27 |
32 |
15 |
18 |
23 |
24 |
24 |
29 |
18 |
20 |
21 |
23 |
23 |
28 |
13 |
18 |
16 |
19 |
|
FM |
10 |
13 |
16 |
19 |
20 |
24 |
6 |
10 |
13 |
16 |
16 |
19 |
9 |
10 |
12 |
14 |
14 |
17 |
7 |
9 |
10 |
12 |
|
|
60cm |
F I |
22 |
25 |
28 |
30 |
30 |
36 |
18 |
20 |
26 |
27 |
28 |
33 |
20 |
23 |
24 |
26 |
26 |
31 |
15 |
18 |
18 |
22 |
|
FM |
11 |
14 |
17 |
20 |
21 |
25 |
9 |
11 |
14 |
17 |
17 |
20 |
9 |
11 |
12 |
15 |
15 |
18 |
8 |
9 |
10 |
12 |
|
|
Snook and Ciriello – towing actions - FEMALES |
|||||||||||||||||||||||
|
DISTANCE |
2 metres |
7,5 metres |
15 metres |
60 metres |
|||||||||||||||||||
|
Action every: |
6s |
12s |
1m |
5m |
30m |
8h |
15s |
22s |
1m |
5m |
30m |
8h |
25s |
35s |
1m |
5m |
30m |
8h |
2m |
5m |
30m |
8h |
|
|
Height of hands |
|||||||||||||||||||||||
|
135cm |
F I |
13 |
16 |
17 |
20 |
21 |
22 |
13 |
14 |
16 |
18 |
19 |
20 |
10 |
12 |
13 |
15 |
16 |
17 |
12 |
13 |
14 |
15 |
|
FM |
6 |
9 |
10 |
11 |
12 |
15 |
7 |
8 |
9 |
10 |
11 |
13 |
6 |
7 |
7 |
8 |
9 |
11 |
5 |
5 |
5 |
7 |
|
|
90cm |
F I |
14 |
16 |
18 |
21 |
22 |
23 |
14 |
15 |
15 |
19 |
20 |
21 |
10 |
12 |
14 |
16 |
17 |
18 |
12 |
13 |
14 |
16 |
|
FM |
6 |
9 |
10 |
11 |
12 |
14 |
7 |
8 |
9 |
10 |
10 |
13 |
5 |
6 |
7 |
8 |
9 |
11 |
5 |
5 |
5 |
7 |
|
|
60cm |
F I |
15 |
17 |
19 |
22 |
23 |
24 |
15 |
16 |
17 |
20 |
21 |
22 |
11 |
13 |
15 |
17 |
18 |
19 |
13 |
14 |
15 |
17 |
|
FM |
5 |
8 |
9 |
10 |
11 |
13 |
6 |
7 |
8 |
9 |
10 |
12 |
5 |
6 |
7 |
7 |
8 |
10 |
4 |
5 |
5 |
6 |
|
Snook and Ciriello – flat displacement – Tab. 3
Maximum starting forces (FI) and maintenance forces (FM), expressed in kilograms (Kg), recommended for working healthy adults, according to: sex, displacement distance, action frequency, height of the hands from the ground.
|
Snook and Ciriello – flat displacement - MALES |
|||||||||||||||||||
|
DISTANCE |
2 metres |
7,5 metres |
15 metres |
||||||||||||||||
|
Action every: |
6s |
12s |
1m |
5m |
30m |
8h |
15s |
22s |
1m |
5m |
30m |
8h |
25s |
35s |
1m |
5m |
30m |
8h |
|
|
Height of hands |
|||||||||||||||||||
|
110cm |
10 |
14 |
17 |
19 |
21 |
25 |
9 |
11 |
15 |
17 |
19 |
22 |
10 |
11 |
13 |
15 |
17 |
20 |
|
|
80cm |
13 |
17 |
21 |
23 |
26 |
31 |
11 |
14 |
18 |
21 |
23 |
27 |
13 |
15 |
17 |
20 |
22 |
26 |
|
|
Snook and Ciriello – flat displacement - FEMALES |
|||||||||||||||||||
|
DISTANCE |
2 metres |
7,5 metres |
15 metres |
||||||||||||||||
|
Action every: |
6s |
12s |
1m |
5m |
30m |
8h |
15s |
22s |
1m |
5m |
30m |
8h |
25s |
35s |
1m |
5m |
30m |
8h |
|
|
Height of hands |
|||||||||||||||||||
|
110cm |
11 |
12 |
13 |
13 |
13 |
18 |
9 |
10 |
13 |
13 |
13 |
18 |
10 |
11 |
12 |
12 |
12 |
16 |
|
|
80cm |
13 |
14 |
16 |
16 |
16 |
22 |
10 |
11 |
14 |
14 |
14 |
20 |
12 |
12 |
14 |
14 |
14 |
19 |
|
Snook and Ciriello – reading and interpretation of exposure index
These indicators are the ratio between weight (force) actually displaced in a specific working situation (measured with force gauge) and weight (force) recommended for that action in tables 1-2-3.
|
Snook and Ciriello – Risk assessment - Tab.4 |
|
| Risk synthetic index is 0.75 (recognisable as green area) | The situation is acceptable and any specific intervention is not required. |
| Risk synthetic index is from 0.76 and 1.25 (recognisable as yellow area) | The situation is close to the limits, a portion of population (estimated between 11% and 20% of each subgroup of sex and age) cannot be protected and cautions are required, although an immediate intervention is not necessary. It is recommended to enable the training and medical surveillance of staff. Where this is possible, it is preferable to reduce risk with structural and organizational interventions in order to go in green area. (risk index 0.75) |
| Risk synthetic index is > 1.25 (recognisable as red area) | The situation can result in a risk for relevant percentages of subjects; therefore, a primary intervention is required. The higher the risk, the higher is the index. On this basis, priority of remediation should be programmed. |
| Risk synthetic index is more than 3 (recognisable as violet area) | For situations with index higher than 3, an immediate preventing action is needed; intervention is still necessary and not postponable for long time even with indexes ranging between 1.25 and 3. |
