1 Introduction

The aging process in China is accelerating faster and faster. It is the whole society’s responsibility to create a reasonable and livable social environment and make the senior people have an ideal senectitude. For a person, at any age, one of the important influential factors that reflect his degree of independence and social participation is personal travelling behaviors [1]. Rest facilities are major components for any outdoor public space. With the increasement of age, functions of senior people’s joints and muscles will fade away which may result in a negative using experience for these facilities. Design in this field is of significance for senior citizens’ travelling as well as using spaces effectively and participating in social events. For senior people who always have plenty of leisure time, public rest facilities are more meaningful and valuable.

There is a great difference among cities distributed in various regions of China in the level of development. And China has a vast and increasing population which is distinct from many advanced Western countries. Thus it is not appropriate to follow western design results directly. Current studies about Chinese public facilities are always surveys rather than design researches. Based on the characteristics of physical, psychological and resting behaviors of the elderly in China, this study collected data from elder subjects and factor analysis is used to find out the common factors behind their needs. Targeted design can be proposed according to the implication of these factors which have a significant influence on the use of rest facilities. The application of Chinese senior people’s body dimension is also meaningful in this study.

2 Background

2.1 Physical Characteristics and Rest Postures of the Elderly

When a man begins the veteran stage of his life, a rapid decline in various physiological parameters will appear. Among them, muscular flaccidity and osteoporosis can induce a decrease in maximum force of bones and torque of joints. For the elderly, it is difficult to force again if the body is kept in a stationary state for a period of time. Thus it is not suitable to have a sedentary behavior. Domestic research has demonstrated that compared with the lower limbs, the level of the attenuation and atrophy of the number of muscle fibers in the upper limbs is lower, and older people always show a physical movement disorder in their legs first [2]. Diseases which are common in the elderly group, such as arthritis and rheumatism, may also reduce their ability to move the lower limbs. Therefore, it is common that old people are not able to stand up easily after sitting down and a more suitable rest posture is essential.

On the aspect of joint activity degree, there is little difference between the male and the female old people. But compared with the middle-aged, the degree of the elderly’s narrows [3]. Leaning is a reasonable rest posture. With the body leaning against something such as rest facilities rather than sitting down deeply, the lower limbs’ forcing difficulty to stand up can be avoided and the limitation of joint activity can be alleviated, while the elderly’s rest demands can be satisfied. Thus it is rational to take leaning posture into consideration in the design of public rest facilities.

2.2 Chinese Senior People’s Rest Behaviors in Public Space

Hypothesis—from Behaviors to Postures

Traditional Chinese senior people are always family-oriented. After retiring, they prefer helping their sons or daughters take care of their offsprings to having a long journey or working out for a long time. Chinese senior people are used to have regular activities in a particular public space which is always home-centered. In this way they can carry on the housework after finishing outdoor activities. The main rest-behavior-characteristics in public space include: watching others, communicating with each other, relaxing and meditating, and resting in the course of a walk [4]. Different behaviors represent their unique psychological and behavioral characteristics, with corresponding postures such as deeply seating, shallowly seating and leaning. The four kinds of behaviors are not seperated from each other but overlapping. The elderly’s demands for rest facilities can be decomposed by clarifying these characteristics and analyzing the common postures.

Behavior A–Watching others’ behaviors. For the sakes of aging, leaving from work and a narrowed social circle, compensatory psychology prominently functions in senior people. Watching others’ behaviors can bring about an experience that cannot be obtained by themselves directly and achieve some kind of emotional compensation. When such a behavior happens, senior people always choose a chair with a backrest and present a posture of sitting deeply. But a part of them also sit shallowly to interact with the observed objects conveniently.

Behavior B–Communicating with each other. Senior people without working stress are inclined to sit together encircledly and communicate with each other when they rest in public space. The main rest posture in this situation is sitting shallowly with raising their heads. Such a posture can show some kind of inclusiveness and help them integrate into the others.

Behavior C–Relaxing and meditating. It can be seen frequently that senior people resting on the public seat, thinking by themselves and enjoying the surrounding environment. At such a moment, the seats always distribute along a hollow space with a strong privacy, such as an area with a lot of plants. A posture of sitting deeply is common in this context so that the senior people can get a space for meditating.

Behavior D–Resting in the course of a walk. Compared with the youth, the majority of senior people hold a living-oriented travelling purpose rather than a survival-oriented one. Without a necessity to work, walking accounts for a high proportion in the way of travelling. Nevertheless senior people generally have a poor physical function. Although willing to walk, it is difficult to continue for a long time. In the break of a walk, a short rest is necessary for the elderly group. This situation is of some kind of temporary nature, so the most common posture is sitting shallowly while sometimes leaning behaviors can be seen. For this behavior, supporting frames or tiny brackets are always used by senior people for a transient rest.

By means of field observation, it can be seen that the posture of sitting deeply rarely appears in outdoor public space. And it does not conform to the physiological characteristics of the elderly.

Outdoor rest facilities include chairs, benches, stools, lean brackets etc. On some common public facilities, posture related problems such as unsuitable depth of seat (the buttock-popliteal length), too many bars on the interactive parts or uncomfortable backrest angle may impose many obstacles on senior people (Fig. 1). In order to assess the rationality of the rest postures mentioned above, evaluation system needs to be set up from the perspective of the user’s cognition to produce a perceptual evaluation.

Fig. 1.
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Typical rest facilities with serious problems

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Assessment of Suitable Postures

In this part, Analytic Hierarchy Process (AHP) is used to assess the three postures which are deeply seating, shallowly seating and leaning. The data comes from senior people’s perceptual evaluation. From the point of users, this part tries to judge which posture is most suited for senior people.

AHP is a method combining qualitative judgment and quantitative analysis and is suitable for assessing design proposals which are always of fuzziness and nondeterminacy. In domestic field of industrial design research, some researchers have assessed designs of product appearance or interactive space such as aircraft cabin by this method, and obtained persuasive conclusions [5, 6]. The evaluation system includes three levels which are target layer, standard layer and object layer. In order to obtain the evaluation results, a higher level of elements will be used as the standard to make a comparison between elements of a lower level. And an evaluation matrix is set up. On the selection of evaluation indicators, the Technology Acceptance Model offers two key points: perceived usefulness and perceived ease of use [7]. Besides, as a public product, design for the rest facilities needs to take compatibility and perceived danger into account, which mean whether the new product is in conformity with the user’s inherent experience and whether they may feel dangerous. Therefore, four evaluation indicators are proposed which are perceived usefulness, perceived ease of use, compatibility and perceived danger. The specific connotation of the four indicators was explained to the subjects during the data collection. The target of this evaluation system is “A Comfort Degree Assessment of the Elderly-oriented Public Resting Facility”, and the assessed objects are the three rest postures. The final AHP mdel is shown in Fig. 2.

Fig. 2.
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AHP model for assessment of the elderly’s rest postures

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30 raters are invited to make an assessment to the three postures. Every rater’s judgment matrix is calculated to seek an ordering weight. All the raters’ ordering weight values are dealt with to get a geometric mean and produce the group decision. Using the software yaahp 10.3, total order weight values of every rater’s judgment matrix are generated. C.I. Values of all the raters’ judgment matrices are less than 0.1, passing the consistency test. The group-decision results are listed as Table 1:

Table 1. Results of AHP model
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From the results it can be seen that leaning is the most recognised posture for older users (W = 0.3556). And it is in the first rank in the sense of perceived usefulness and perceived ease of use.

The second one is shallowly seating and not much less than the lean posture (W = 0.3371). Among all the indicators, shallowly seating gets a highest weight value on compatibility, which conforms to common sense.

On the aspect of perceived danger, there is still a shortage of leaning posture. Users generally feel that leaning is of the highest risk while deeply sitting is the safest one among the three postures. Although this result is reasonable, it also exposes the opportunities of future designs.

The main reason why users consider leaning as useful and easy to use but feel dangerous is that leaning is an unstable posture. Existing leaning frames are always with only two contact points, which are buttocks and feet, as interaction parts. Weight of the torso will cause the body to slip down from the supporting surface. So compared with sitting position which makes the body almost impossible to slide, the whole body is in a moving state in the leaning status and such a posture imposes an unstable experience in perception on the users.

Although deeply sitting is stable, it does not conform to the physiological characteristics of the lower limbs of the elderly. A reasonable solution for designers to work out is to set up a support under users’ knee and make the two contact points of the leaning position into three and forming a stable triangular structure.

In order to achieve such a design, it is pivotal to clarify the significance level of the postures’ influence on usability of public resting facilities. And whether there are other influencial factors is also necessary to identify for putting forward a design proposal. The next part focuses on the two pieces of information.

3 Method

3.1 Survey Design

Design of rest facilities belongs to the domain of humanistic care rather than a high-tech or a new skill keeping pace with the times. From the point of the elderly, problems of public rest facilities always exist on aspects such as distribution of the facilities, interval distance, scale and size of the product, users’ perceptual factors and so on. Rosemary’s study for the environment and health of different regions of Glasgow, Scotland had pointed out that there are not enough seats for the elderly to rest on their way of walking [8]. Study of Maria from Switzerland also showed that senior people hold the view that height of public seats should not be too low [9]. According to the early research, such kind of problems exist on contemporary Chinese urban public rest facilities in the same way. These problems are less involved in the development of technology and belongs to the perceptual level of people to a larger extent. To solve these problems, there are not many obstacles on the technical level. This part of research aims at clarifying the depth of the sensibility of certain group of users by quantifying their perceptual demands.

3.2 Data Collection

The research focuses on senior people’s psychological feelings and needs. By means of random visits, 48 senior people from three typical districts in Beijing, which are Haidian District, Shijingshan District and Shunyi District, are interviewed. The subjects are asked to speak out what they care about on public rest facilities and the everyday times of using this kind of facilities are recorded. By corpus analysis, frequency of problems that is cared by the elderly is accumulated and it can be found that 17 problems appear frequently. The result and key words of the problems are listed as Fig. 3.

Fig. 3.
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Frequency accumulation of problems cared by senior people (times)

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Likert 7-level scale is used to compile a questionaire. And 200 elder users were invited to score the 17 problems. Score 1 means the user does not care the problem at all and the value 7 means the subject pays an extreme attention to it. Score 1–7 show the level of concern of the elderly about the issue. A total of 186 valid questionnaires were collected.

4 Result

4.1 Factor Analysis for Users’ Demands

The Cronbach’s α of this questionaire is α = 0.907 and shows a high level of internal consistency reliability. Due to the large number of variables, factor analysis is used to analyze the data (n = 186). The aim is to extract commonalities from variable groups and classify problems with a same essential into one factor to simplify variable information and find core issues.

Kaiser-Meyer-Olkin Test shows a KMO value of 0.820. And Bartlett Test of Sphericity unfolds a result which is very significant (p < 0.001). It means the 17 variables of this research is suitable for factor analysis.

The factors with an eigenvalue greater than 1 are reserved and we can get 4 common factors. The cumulative percentage of variance reaches 78.432%. After varimax rotation, the results are listed as Table 2:

Table 2. Results of factor analysis
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After analyzing the information from the variables contained in the four common factors in Table 1 and extracting the inherent concepts, the four factors can be named. F1 can summarize information of eight variables. It can be found that all these variables reflect problems about postures and physical unconvenience. F2 summarizes four variables which all illustrate shortcomings about form and appearance, such as problems of surface hardness, materials, style and colors. As is described above, senior people pay attention to practicability as well as appearance of products. F3 summarizes information of three variables showing difficulties or dangers that such facilities may cause. F4 summarizes two variables which are about using experience, such as communication and vision at night. Thus the four factors can be named as POSTURE, EXTERIOR, DANGER and EXPERIENCE. These four aspects of problems are what users care about most.

4.2 Effect of the Factors

Frequency of use of certain product reflects whether users have enough recognition for it. The more times a product is used everyday, the more trust and recognition the users have. On the contrary, for the facility which is seldom used by citizens, it shows that people have a certain degree of skepticism about it. Thus the frequency of use of rest facilities is considered as a dependent variable. The four common factors have some effects on the variation of the frequency of use of rest facilities or not is a key point for the product design. And whether the effects are positive or negative as well as how is the significance level of the effects need to be confirmed.

Calculate the scores of the four common factors and take the scores as independent variables. As is mentioned above, the everyday frequency of use of rest facilities is considered as the dependent variable. In this way a regression model can be set up. Replacing the original variables by factor scores can retain the main initial information as well as avoiding multicollinearity problems caused by variables reflecting people’s subjective opinions. The results are listed as Table 3.

Table 3. Results of regression analysis
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The coefficient of determination of this model is R2 = 0.702. It means the variation of independent variables can explain more than 70% of the dependent variable’s variation. The goodness of fit is relatively ideal. The Durbin-Watson value is 2.913, which shows a weak relevance between the residuals. They are independent from each other. From the results it can be seen that three common factors have a significant influence on the frequency of use (p < 0.01), which are F1, F2 and F3. They are not incidental random occurrances. Designing based on the three factors is justified. F4 is not significant (p > 0.05) so the experience of communication or vision at night is not a critical problem in public rest facilities design.

From users’ demand analysis it can be known that factors of POSTURE, EXTERIOR and DANGER have seriously affected the frequency of use of rest facilities for the elderly. In order to satisfy senior people’s needs for rest facilities by design, it is necessary to propose solutions corresponding to these factors. And users’ experience may be improved.

5 Discussion

5.1 A Design Proposal of Leaning Facility

It can be known from Table 3 that POSTURE influences the frequency of use most. And this fully exposes the poture problems in existing products. Optimizing the rest postures by design is a rational way to make the facility meet senior people’s needs. Besides, the main problems reflected in Fig. 3 show a fact that in view of exterior, the surface should be rich in morphological changes with a smooth transition in shapes and avoiding a feeling of hard texture. The surface should be glossy and easy to clean. The shape should present a sense of design which is elaborate and delicate. And the colors ought to be bright and novel. Compared with boxy lines and shapes common in traditional seats, a glossy and smooth shape should be the first choice of designers.

In view of DANGER, the handrails should be canceled and make the line-change of the edges mellow. Acute angles and branches must be refrained from the shaping work. The product design is achieved based on demands analysis. The proposal is as Fig. 4.

Fig. 4.
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A design proposal

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The transition of different parts of this design is rounded and mellow. Its shape comes from the form of pistils growing from petals of a bud, with a feeling of ascending and stretching to represent senior people’s standing up gracefully and the gap between the products and users can be perceptually narrowing to some extent. The signifier and signified of the exterior semantic meanings can be combined together effectively in this way.

According to the results listed in Table 1, the posture applied in this design is leaning by which senior people do not have to sit down utterly when using and thus it can be more convenient and easier for them to stand up. The facility ensures that the angle between the user’s torso and thighs is about 130° under the leaning posture. Such an leaning attitude is comfortable and can save a lot of labour when standing up. In order to prevent the seating body from declining, a knee-support frame is added on the position of legs. The outer layer of the frame is wrapped in soft material which can reduce muscle stress. This angle can make the spine of the elderly be kept under a natural posture and reduce the force of lumbar vertebra. Even without a waist cushion, the elderly will not feel tired.

5.2 Positioning

Volume of public rest facilities depends on the locus in which it is located. And the locus selection depends on people’s needs. Hieronymus’s study showed that setting up seats in places such as parks, squares or game fields can attract the elderly to take a walk here. The appropriate walking distance for the elderly is 150 m and rest facilities ought to be set every 150 m at least, along the edges of their action fields and on both sides of roads where the frequency of use is high [10]. This requires that volume of the facility should not be too large or take up a lot of space. It must be exquisite enough and easy to dismantle.

Besides, diversified psychological and behavioral characteristics of the elderly require the design to be provided with a variety of modes in assembling and arranging under the premise of conforming to human-machine relationship. Therefore, designers should take the spacial size of a regional system into account, which needs the design can be presented either in a combination of a group of products or by a single unit.

Chinese senior people always hold various recreational activities in parks. Rest facilities ought to help to build a site for senior people’s exchange and interaction. This is important for enhancing their sense of existence in the society and relieving their negative emotions in life [11]. Thus in the aspect of modular combination, the design proposal adopts a smaller volume and ensures the facility conforms to a sense of aesthetics either it is placed in a circle or in a straight row (Fig. 5).

Fig. 5.
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Application scene of the proposal

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5.3 Scale and Size

From the age group 40–44, people’s height begins to decrease significantly with age and the trend will last for the latter half of life. Sitting height and extensional range of limbs hold the same downward trend [12, 13]. Such reduction demands the facility design to take Chinese senior people’s body dimension into consideration. Domestic researches have given out relative conclusions [3, 14].

Based on Chinese elderly’s body dimension data, using the large percentile size of male senior people to set the height and width of leaning surface and backrest so that the big and tall senior people can lean on it. The sitting hip breadth of 90th percentile of Chinese male elderly is 399 mm [3]. Considering the thickness of clothes in winter, the widest part of the surface is set as about 420 mm.

Using medium percentile size of female senior people to design the knee supporting frame and preventing males’ legs from being unable to be put in which is brought about by small size, or females’ knee from reaching the frame which is caused by a large size. The method to obtain the size is subtracting buttock-popliteal length from buttock-knee length to get the thickness of shin. Considering the thickness of trousers in winter and basic leg movements, the distance between the knee supporting frame and leaning surface bracket is ascertained.

The distance from the top of the leaning surface to the ground is about 1300 mm which is determined by male elderly’s large percentile size. The volume is small and suitable to be put in a variety of indoor and outdoor occasions.

6 Conclusion

In the aging society, attention to the using experience of the disadvantaged senior people represents the degree of social civilization. Product design should not focus on the appearance and economical efficiency only. Under such a principle, the research analyzes the leaning posture’s merits and dismerits. Physical functions of senior people’s lower limbs declines and sitting down completely is not a good way to rest. Leaning is useful and easy to use but makes elder users feel dangerous. By comparison of three postures, an improved rest posture is proposed.

By means of factor analysis and regression analysis, significant effective results are obtained to guide design works. From aspects of posture, exterior, danger and experience, users’ perceptual cognition and physical characteristics are taken into consideration and well-directed design points are put forward.

Relative research about elder users’ behaviors and experience are still keeping on. Based on the results of this study, more design proposals can be made and it is appropriate to select an optimized one as the solution to problems of public rest facilities.

Finally, a limitation of the current study is that the analysis relies on the use of perceptual judgement which limits to a certain extent the validity of the analysis. In next phase of research therefore, a 1:1 model would be made for subjects to lean on and to evaluate their experience by variation of physical signals such as information from EEG. Additional insights into senior people’s demands would be brought about.