KING OR EMPEROR?
                                                 Kuijt-Evers LFM1
                                    1. Department of Work and Productivity
                    TNO Quality of Life, PO box 718, NL-2130 AS Hoofddorp, the Netherlands

            Human Centered Design aims to include the end-users opinion in the design
            process of new products. But should the designer always listen to the end-
            user or should he in some cases ignore the end-users’ opinion? And what
            can be the consequences of this? This paper describes a design case of the
            masonry trowels, in which the bricklayers were involved in several steps.
            The design process is described as well as the dilemma the ergonomists
            were facing. In this session we will discuss this dilemma.

            Human Centered Design, hand tools

    1        Introduction
    Human Centered Design can be seen as a constructive combination of market research
    and product development, because it brings future or possible end-users into the
    development process (Steen et al., 2007). This can solve a key problem in innovation,
    which is that too many projects suffer from ‘insufficient market input, a failure to build
    in the voice of the customer, and a lack of understanding of the market place’ (Cooper
    1999). Kujala (2003) concludes that involving end-users in research and design
    activities can have diverse positive effects, like an increased quality or speed of the
    research and design process, a better match between a product and end-users’ needs or
    preferences and improved end-users’ satisfaction.
           Steen et al (2007) distinguish several methods/practices of Human Centered
    Design, like participatory design, ethnographic field work, lead user approach,
    contextual design, co-design and empathic designing. All these methodes and practices
    have their own characteristics and focusses, but they have one thing common: end-users
    play a role in the design process. In some methodes end-users initiate the process and
    are moving towards the researcher/designer (i.e., participatory design, lead-user
    approach, co-design) and in other methods it goes the other way around (e.g., empathic
    design, ethnographic field work, contextual design). Another difference between these
    Human Centered Design Methods is that some methods are especially useful to focus on
    the current situation and to solve the problems that occur (participatory design,
    ethnograpic field work), and other methods are more suitable to generate new ideas for
    the future application of current or new technologies (co-designing, empathic design). A
    third group of methods translate the findings of the current situation into future
    applications (lead user approach, contextual design). Based on this description it seems
    that these methods can be clearly seperated, but in reality they are often combined and
    adapted. Moreover, they perform differently in different settings (instead of being
             Anyway, we should not forget the main goals of user involvement in the design
    processes, namely to invent more creative products that better fit the users demands’

C. Berlin and L-O. Bligård (Eds): Proceedings of the 39th Nordic Ergonomics Society Conference, Oct 1-3 2007, Lysekil, Sweden
    and to create support for the new product. In what way the user is involved in the
    project and what influence he has on the final product depends on the method which is
    used, the role he has and the way the designer or researcher listens to him. But should
    the designer always listen to the end-user or should the designer make his own decisions
    (against the end-users’ opinion) in some situations? The aim of this paper is to illustrate
    this kind of dilemmas which designers are facing during a human centered design
    process. The case-study, that is described here, is the design process of a new masonry
    trowel. This case-study gives input for discussion.
            In the next session, the design process of het masonry trowel is described. The
    steps in the process are identified as well as the ways the end-users were involved. In
    the third session, the dillema the designers were facing is clarified and the paper ends
    with some final words about how the designers dealed with the dillema.

    2       Design case: the new masonry trovel
    Bricklaying is a heavy physical job. During the last decennia, much attention was paid
    to back problems of masonry workers. A number of improvements were developed to
    reduce the physical load of the back and the heaviness of the physical work (Molen et
    al., 2005). Almost no attention was paid to the physical load of the upper extremities.
    According to figures of Arbouw (Arbouw, 2001), masonry workers reported more
    complaints on shoulders, arms, wrists, hands and fingers than other construction
    workers. In order to decrease the amount of physical complaints of the upper extremity,
    the main hand tool of the masonry worker --the trowel-- was scrutinized. Masonry
    workers were involved in several steps of the design process.

    2.1 Step 1: Identifying ergonomic problems
    Firstly, the ergonomical problems were identified during observations and interviews
    with masoners in the field. The ergonomist visited a construction site and a bricklaying
    training to collect information about the use of the trowel. Video and photo recordings
    were made, in order to illustrate the brick layers’ postures and movements. These were
    used to identify the major ergonomics problems in working with the trowel. According
    to the expert opinion of four ergonomists, four major problems occur when using the
    • The return movement of the fore arm and wrist to throw the mortar on the bricks
        causes extreme postures in the elbow and wrist (Figure 1) Moreover, when working
        between hip and shoulder height (and above), the elevation of the upper arm even
        increases the physical load on the shoulder;
    • The weight of the trowel and the mortar combined with a large moment arm of the
        centre of the trowel’s mass results in a high wrist load moment value;
    • The handle of the trowel is not optimized (material, size, shape, finishing);
    • Cutting bricks with the trowel results in high elbow and wrist loads and should be

C. Berlin and L-O. Bligård (Eds): Proceedings of the 39th Nordic Ergonomics Society Conference, Oct 1-3 2007, Lysekil, Sweden
     Figure 1 akward return movement

    Additionally, the masoner’s support for a new trowel was asked. Most of them said they
    would like to try a new one, but that they could not imagine how the traditional trowel
    could be improved. Nevertheless, they agreed that improvements of the trowel were
    needed, as the design of the traditional trowel is very old. Finally, a literature study took
    place on the topic of trowels other countries.
        Hence, during the first step the ergonomist visited the user at the work place to get
    insight in the way the trowel is used. The users were involved in the process, as they
    could give their opinion during the interviews and show the problems they have to deal

    2.2 Step 2: Generating ideas for new design
    Four ergonomists and an industrial designer took part of a brainstorm in which solutions
    for the ergonomic problems were generated. The possible solutions are listed below:
    • The handle should be located above the trowel blade to reduce the wrist load;
    • The blade of the trowel should be smaller, in order to reduce the weight of trowel
        with mortar;
    • Redesign of the trowel blade to reduce awkward postures and movements;
    • Repositioning of the blade with regard to the handle to reduce awkward postures and
    • Provide several possibilities to gasp the handle in order to reduce awkward postures
        and movements;
    • design a separate tool (sabre) to cut the bricks. In that way it is not needed to cut
        bricks with the trowel. This makes it easier to design a new trowel which reduces
        the work load, as cutting a brick and minimizing physical load of the upper
        extremities are contradictionary demands.

    Based on these solutions several ideas for a new trowel were developed. Five of the
    most favourable designs (Figure 2) were elaborated in technical drawings, which were
    transformed into test models by rapid prototyping.

C. Berlin and L-O. Bligård (Eds): Proceedings of the 39th Nordic Ergonomics Society Conference, Oct 1-3 2007, Lysekil, Sweden
    test model 1      test model 2       test model 3                          test model 4             test model 5
    Figure 2 Sketches of the test models

    2.3 Step 3: Evaluation of five test models
    The five test models were evaluated by masonry workers as well as ergonomists.
    Masonry workers of five construction sites all over the country evaluated the test
    models. The masoners tried the models during their work. After they used a model, they
    were (systematically) interviewed by the ergonomist. Additionally, three ergonomists
    evaluated the trowels during an expert meeting.
        The masoners opinion about test model 1 was that the position of the handle
    regarding the blade was not good. They had to apply a large grip force to hold the blade
    horizontal due to rotating moment caused by the load of the mortar. The ergonomists
    agreed on this and test model 1 was abandonded. Test model 2 was too large, which
    influenced the masoners’ opinion. But in fact it did not work for the same reason as test
    model 1. The orientation of the handle regarding the blade was not good. Test model 3
    and 4 looked rather familiar, the difference is the orientation of the handle and the shape
    of the blade at the front end. These trowels were chosen by the masoners. Although,
    they had some comments. The distance between the handle and the blade was too small
    in test model 4 (which leads to mortar on the fingers). Moreover, they could not cut
    bricks with this trowel and that was seen as a disadvantage by the bricklayers. Test
    model 5 was an alternative for the traditional sabre, but this one is equipped with a
        Based on the results of the try-out and the expert meeting, two favourable models
    were chosen. These are model 3 and 4 (Figure 2). These models were further adapted to
    meet the recommendations of the masoners and ergonomists. After that two prototypes
    were made of the new design.

    2.4 Step 4: Field-study to compare two prototypes with the traditional trowel
    The prototypes of the new trowels were evaluated in a field study. 13 masoners
    participated in five separate construction places in the Netherlands. The main goals of
    the field study were to evaluate the ergonomic quality (including physical load
    measurements) and the functionality of the two new designed trowels compared to the
    traditional trowel (Figure 3).

C. Berlin and L-O. Bligård (Eds): Proceedings of the 39th Nordic Ergonomics Society Conference, Oct 1-3 2007, Lysekil, Sweden
                Figure 3 Two prototypes designed trowels compared to the
                traditional trowel

    The field study consisted of three parts: 1) Posture recording (by goniometrics) of
    shoulder, fore arm and wrist during the tasks that the bricklayer perform using their
    trowel 2) Calculation of the wrist load moment value and 3) Questioning the
    bricklayers’ experience after using the prototypes.
        The posture recording showed that the use of prototype 2 (left in figure 3) resulted in
    a significantly shorter exposure to an extreme wrist posture (i.e., ulnar deviation) than
    prototype 1 (in the middle of figure) and the traditional trowel (right in figure 3).
    Furthermore, the wrist load value was significantly lower for prototype 2 compared to
    prototype 1 and the traditional trowel.
        The brick-layers mentioned that the functionality, user friendless and work
    performance are better for the traditional trowel compared to both prototypes. Cutting
    stones, spreading mortar in corners and stirring mortar are things which can better be
    done using the traditional trowel in stead of using the prototypes, according to the
    bricklayers. Further, they say that the prototypes have a good fit in the hand and that
    shovelling and spreading mortar using the prototypes causes less physical load on the
    upper extremities compared to the traditional trowel.

    3 User: King or emperor?
    The dilemma the ergonomists were faced with is: Should they listen to the comments of
    the end-user regarding the functionality of the tool (stirring mortar, cutting stones) or
    should they ignore these comments and focus on the good results of decrease of the
    physical work load? Or should they return in the design cycle and generate new ideas
    which solve as well the physical problems as the shortcomings on functionality? And
    should the ergonomists admit to the requirement of the masoners regarding cutting
    bricks with the trowel, which is undesired from an ergonomical point of view? The
    result of ignoring the comments of the end-user could be that no one would buy the new
    trowel and all masoners would go on working with the traditional trowel design which
    exists for more than a century. No ergonomic improvement would be produced in that
    case. This dillema will be discussed in the work shop.

    4 Final words
    The ergonomists could not choose if the end-user was king of emperor. Therefore, they

C. Berlin and L-O. Bligård (Eds): Proceedings of the 39th Nordic Ergonomics Society Conference, Oct 1-3 2007, Lysekil, Sweden
    decided not to choose....and designed two trowels! They implemented the new trowel as
    tested in the field study (Figure 5) and to redesign the traditional trowel (Figure 6).

    Figure 5 New trowel                                         Figure 6 Redesign of traditional trowel

    They did forsee that it would be very hard to implement the new trowel, despite the
    ergonomic benefits of the new design and the user involvement during the design
    process. Especially, because they decided not to meet with all the users’ requirements
    like cutting bricks with the trowel. Moreover, a new working technique is required to
    use the new trowel in an appropriate way. The new working technique eliminates the
    very loaded return movement of the forearm. Therefore, the new masonry trowel is
    introduced through providing the new trowel to all first and second year students of all
    bricklaying educations in the Netherlands.
        To meet the current masonry workers, a redesign of the traditional trowel (Figure 6)
    was made, which also reduces the wrist load. However, working with the redesigned
    trowel leads to less decrease in physical load of the upper extremities than was achieved
    with the new design. However, it is easier to spread mortar in corners with this trowel
    and…it looks more like the traditional trowel.
            Until now, it seems to work out very well. The first reactions of both tools are
    positive. The technical committee of the AVM (association of bricklayer companies) is
    working out some new techniques to set the profiles in such a way that it is easier to
    spread the mortar in the corners

    5 References
    Arbouw, Bedrijfstakatlas 1998/1999. Arbouw, Amsterdam, 2001.
    Cooper, R. 1999. The invisible success factors in product innovation. Journal of Product
    Innovation Management. 16 (2): 115-148.
    Kujala, S. 2003. User involvement: a review of the benefits and challenges. Behaviour
    and Information Technology. 22 (1): 1-18.
    Molen H.F. van der, Sluiter J.K., Hulshof C.T.J., Vink P., Van Duivenbooden C.,
    Holman R., Frings-Dresen M.H.W. 2005. Implementation of participatory ergonomics
    intervention in construction companies. Scandinavian Journal of Work Environment &
    Health. 31(3): 191-204.
    Steen, M., Kuijt-Evers, L., Klok, J. 2007. Early user involvement in research and design
    projects- a review of methods and practices. Paper for the 23rd EGOS Colloquium
    (European Group for Organizational Studies). July 5–7, 2007, Vienna.

C. Berlin and L-O. Bligård (Eds): Proceedings of the 39th Nordic Ergonomics Society Conference, Oct 1-3 2007, Lysekil, Sweden

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