History
The author was first hit by the idea of the ERGAN^® method (ERGonomic ANalysis) in 1967, and the project was initiated under his leadership the same year. During the course of events of this project, every single element of the methodhas been scientifically founded and tested in laboratory as well as in field conditions. The project, originally called ARBAN (ARBetsANalys), was first made public on an international conference in Dubrovnik 1977 (ref. 1). Since then, the method has undergone a constant development and been published several times (ref. 2-15). Studies of different parts of the project have been published separately (ref. 16-18) as well as case studies of practical ergonomic situations (ref. 19-25) .

ERGAN^® today
Today, the ERGAN^® method has been thoroughly tested and successfully applied in many different practical projects in trade and industries. Those studies have concerned products as well as production. A few of those studies have  been published, but as most of them were made to exclusive order by client companies, they can not be made publicly available.

The ERGAN^®method is based on three basic ideas

• A work situation that changes continuously can be defined by closely sampled "frozen" situations (compare movie frames or video pictures that, when they are presented in close succession, gives an illusion of movement).
• A complicated over all picture can be divided it into a number of well defined small parts that can be defined and established one by one (compare the construction of a highly complicated machine, e.g. a car, that is put together of a great number of relatively simple parts that each one has been designed and produced separately).
• A well guided subjective rating of a situation makes it possible to integrate a great number of factors that each one can not be defined or measured. The  Borg CR-10 scale is an ideal tool for such ratings (ref. 27).

• First one studies the work site to find out typical situations and how to film it.
• The work situation is filmed for a relatively long period of time.
• The contents of the film is analysed with regard to time and events.
• Representative parts of the film are cut together to a continuous course of events of a typical work situation.
• The film is analysed frame by frame.
• The workload data are processed with the ERGAN^® computer program.
• The peaks of load in the time/workload diagram are identified and numbered.
• The time/workload diagram is compared with the course of events on the film and the reason for each peak established.
• Time/workload diagrams and photos of the work situation at every single peak are arranged on a poster.

Documentation of the work situation The work situation is filmed with a video camera for a relatively long period of time, figure 1. This film is analysed with respect to its content, the frequency of occurrence of different events and the representatively of the content for the work situation. From this film, some typical situations are cut together to a concentrated film that is representative for the work situation as a whole. This film is then analysed frame by frame with fixed intervals of one or a few seconds.

Figure 1

Observing the human body Six principal parts of the human body are regarded: head/neck, trunk/back, right and left arm, right and left leg. Each of those parts are made up of "functional units": the head/neck and trunk/back are each regarded as one single functional unit, but the arms and legs are regarded as three functional units each. This makes a total of 14 functional units that shall be considered on each still, figure 2.

Figure 2

Physical load factors
It is assumed that any physical load that the human body is exposed to is composed of one or several of the following factors:

• The posture
• The developed force
• Static workload
• External forces and vibrations

Assessing the magnitude of physical load
The magnitude of the physical load caused by the posture, the developed force and the external forces are assessed by the using the Borg CR-10 scale^© (CR = Category Rating). This scale is composed of verbal expressions for the magnitude of physical load, progressively increasing from "Nothing at all" to "Very, very high", and with an indefinite "Maximum". Numerical values from 0 to 10 are assigned to the expressions in a non-linear way, corresponding to the physical response to different levels of load. The Borg scale is used daily in most hospitals all over the world and undisputed in the scientific world.

The static workload is calculated on the base of the three other load factors and the duration of the static situation. After the end of a static load, the method also takes the recovery phase into consideration.
 
 

The ERGAN®guide A guide has been developed as a help for making standardised assessments. It enables the results of all ERGAN® analyses to be reproduced and compared, figure 3. This guide contains information on different levels, making it possible for the user to verify and understand the physiological background: A general introduction and explanation of the object and the basic ideas of the guide.  A general physiologic and anatomic presentation of each functional unit, how it works and the factors that are important when it is exposed to load in different contexts.  Pictures of a number of typical postures and the hereto assigned numerical values in the Borg scale. An explanation of anatomical and physiological factors that influence on the magnitude of physical load follows each picture.  A poster for each functional unit, enabling a quick and simple oversight of possible postures and the allocation of values in the Borg scale.

Figure 3

It is evident that this guide can not contain all possible situations. Interpolation between the given, typical postures and the explaining text in combination with common sense enables the ergonomically educated person to make correct ERGAN^® analyses.

Combination of the physical load data
When all frames of the film have been analysed, the ERGAN^® computer program puts together the workload data into a general, over-all picture. Hereby, the resistance of the different functional units to different types of stress  is taken into consideration. This is based on data of the workload situations and the medical records of about 380.000 Swedish building workers.

Interpretation of the results
The succession of workload data is presented in a time/workload diagram, figure 4. One diagram is produced for each of the six body parts and one for the body as a whole. Each point on those curves can be related to events on the film. Different phases of the work can also be presented with different colours, making it easier to follow the course of events. Every peak on the curve signifies a moment of high physical load. It can be identified and marked. Each instant event that is the cause of the peak is then analysed on the film. It is possible to identify the reason and thus to understand the underlying problem. The peaks are then regarded in relation to each others,  to conclude on the relative importance of different types of events. Some peaks can, for example, be cased by frequently occurring relative low work load, others by rarely occurring extreme peaks or peaks that build up successively due to prolonged static workload. Mostly, the analysis of a work situation contains a combination of such different load situations.
 

Figure 4. A typical ERGAN® poster showing the time/workload diagram and photos of all situations at the numbered high peaks. The Borg CR-10 scale© to the left of the diagram makes it possible to read the magnitude of each single workload peak. The different colours represent different typical phases of the work.

Presentation of the result of an ERGAN^®analysis
The aim of the ERGAN^® analysis is to make the ergonomic situation maximum clear to everybody involved. This makes it possible for all involved to contribute to the solution of the problems. This is achieved by simultaneously presenting the time/workload diagrams, pictures of all situations in which high peaks occurs and the film. It is often practical to put up the diagrams and the photos on a poster. In that case, the film can be presented and the fluctuations of the workload followed on the diagram. The film can also be showed in slow motion or frozen on critical points, making it possible to study and perfectly understand the situation.

Documentation of the results
The film and the poster are the most important pieces of documentation of the study. It is also recommended to put down a description of how the project was carried out and of the most important conclusions. The extent of this written report depends on the nature of the project.

Practical applications
The ERGAN^® method can be used for a number of different purposes:

• To compare different products, "benchmarking". It is possible to identify, measure and compare strong and weak properties of the different products.

• To compare products before and after an improvement or change of construction. An example is the example 2, comparing two milking units with respect to the time needed to perform a certain amount of work and the physical workload during this work.

• To study the course of events and identify critical moments on a workplace or of a product in practical use. Typical examples of this type of application are shown in the figure 3, analysing the cashier's work situation in an IKEA cash-point, and example 1, identification of the critical moment of work when posing corrugated steel sheets on roofs.

• To study the influence of fatigue during a prolonged, repetitive work task. Also this can be seen in example 2, where the old product (red) causes a progressively increasing workload due to static components of the work, while the improved product (blue) produces less physical load and allows recovery during the work.

© Copyright Peter Holzmann 2001