Comparative Study of Design and Type of Work When Assembling Cardboard Beds for Shelters

Abstract

When a disaster strikes, it is an international standard to use make shifts beds in shelters but in Japan, refugees are forced to sleep directly on shelters’ floor for long periods of time. In recent researches, this type of shelter environment was revealed to lead to different secondary health damages or post-disaster related deaths. However, after the 2011 Great East Japan Earthquake, corrugated cardboard make shift beds began to be used in shelters. Their use can help reduce secondary health damages and improve shelters’ environment. From a few hundred to one thousand disaster victims are expected in large scale shelters but corrugated cardboard beds’ assembly demand an important work load and it is desirable to install them promptly to prevent evacuees to sleep on the floor as much as possible. It is necessary to plan the optimization of beds’ assembly. In precedent cases, beds were installed and assembled with the help of volunteers and there was a tendency for groups to be formed and making assembly a collaborative work. However, the division of labor and cooperative work require time and space and it can be frequently inefficient as the limited manpower, related to the disaster, can be seen as wasted. In this research, we focus on differences in movements for individual work and collaborative work in the process of assembling cardboards beds and use these results to reduce unnecessary movements and to render their assembly and set-up easy and efficient.

1 Context and Objectives

Japan is said to be the great country of disaster and since the 2011 Great East Japan Earthquake, various disasters have occurred and when necessary, numerous shelters have been installed. However, it cannot be said that shelters’ environment is good for the evacuees as they are forced to sleep directly on shelters’ cold floor and living in these conditions for a long period has led to numerous secondary health damages. To improve this situation, cardboard beds for shelters were developed (Fig. 1). This cardboard bed has a simple structure and shape making it easy for anyone to assemble it. Also, they are can be mass produced quickly and at a low price. On the other side, assembling a bed requires quite some time and depending on every person’s way of assembly and the use of collaborative work, the time spend assembling the bed could stretch even more. To decrease the burden of the workers, we are aiming to shorten the time necessary by improving the assembly of the cardboard bed and in the first experiment, we have examined efficacy differences between division of work and individual work and in the second experiment, differences between the existing cardboard bed and a newer version with bigger and less parts.

Fig. 1.

Cardboard bed for shelters

Fig. 2.

On On the right, a usual Japanese shelter with bedding directly on the floor or on a thin tatami mat. On the left, a shelter in a Gymnasium where people sleep on the floor

Fig. 3.

Volunteers are making beds (collaborative work)

Fig. 4.

(a) Completed cardboard bed for a family of 3. (b) Completed bed for two persons.

Fig. 5.

Beds in a shelter for 100 evacuees

2 Processes in the Standard Assembly of a Cardboard Bed for Shelters

In the first stage, the total of 24 small cardboard boxes are assembled with a diagonal partition of cardboard inserted in each box and then each 4 boxes are inserted in a sleeve. A rectangle is formed by assembling these 3 exterior sleeves for the length and 2 for the width. Two top boards are placed on this rectangle to form the bed. The final product is pictured in Fig. 1.

3 First Experiment

3.1 Content of the Experiment

The experiment was realized indoor with sufficient space. Using unassembled beds, we asked the participants to assembly in order (A) and (B) work type. Work (A) consist in one group of several persons assembling freely the number of beds equal to the number of persons in the group. In Work (B), each person assemble one bed. The work process was recorded on video camera form beginning to end.

This time, we realized this experiment with the following two groups:

• Group 1: 2 participants; in Work (A) 2 persons made 2 beds and in (B) Work, each of the 2 participants made 1 bed each.

• Group 2: 3 participants; in Work (A) 3 persons made 3 beds and in (B) Work, each of the 3 participants made 1 bed each.

3.2 Method of Analysis

To process to the recorded assembly work analysis, we determined the following elements.

The beginning point of the analysis was considered to be “the first time when one touches the cardboard”, “the last time one takes their hands of the cardboard” is the final point and one sequence of required time was considered as “entire work time”. Situations where “one was waiting without doing nothing” or movements as “holding things and moving” were considered as “wasted time”. However, in the case of “one moving and working”, it was considered as work time. The time obtained from subtracting “Wasted time” to “entire work time” is considered as “actual work time” and for the work (B), we categorized 12 processes in the method of assembling the cardboard bed (Fig. 5).

3.3 Experiment Results

The results of the analysis of the recorded assembly work are represented in Figs. 6 and 7. Individual work analysis dividing each 12 processes worktime was represented in Table 1.

Fig. 6.

Analysis results of work (A)

Fig. 7.

Analysis results of work (B)

Table 1. Required time for each process during individual work

Furthermore, concerning the Fig. 2, the actual worktime, the wasted time and the entire worktime average are respectively 946.6(s), 230.7(s), 1176.3(s), the deviation is for each 178.8(s), 158.4(s), 22.8(s). For the Fig. 3, the average is respectively 709.8(s), 41.7(s), 751.5(s), and the deviation 50.1(s),15.2(s), 42.6(s). Among the two Work items, we realized the F-test and homoscedastic can’t be noticed for the entire worktime only. From this result, we applied Welch test on the entire worktime, for the two other items, we realized the T-test and in every case with p < 0.05, statistical difference were observed. Also, in the 12 processes shown on Table 1, “Tidying up” is in itself an unnecessary process.

3.4 Discussion

In Fig. 2 as well as Fig. 3, as statistical differences were observed in the entire worktime, the wasted time and the actual worktime, it can be said that the division of work takes more time to assembly and produces wasted time. If you look closely at each group in Fig. 2, there is a great variation of wasted time between Group 1 and Group 2. In Group 1, the two persons worked resourcefully but on the other side, Group 2 divided complete the work and it can be thought that it is was the source of waiting time. Also, during the individual work phase, 3 of the 5 participants did not use the assembling method thought to be the fastest and had each a different way to assemble the bed but based on Fig. 3, there is no important variation observable. From this, it appears that during the individual work, the sequence of assembly doesn’t not create a great variation in time.

Moreover, observing Table 1, the processes requiring the most time for the individual work are tapping the ends of the box and also inserting the boxes in the exterior sleeves. Also, one of our participants told us the tapping was troublesome which led us to assume that removing the tapping work could lead to decrease substantially worktime.

4 Second Experiment

4.1 Experiment Content

The experiment was realized indoor with sufficient space and we used two different types of cardboard beds: the existing type of made with 24 small boxes and a new prototype using 12 larger boxes, half the number of the previous type with one box being the size of 2 small boxes. We asked the participants to make each time of bed alone and we recorded their work from beginning to end. Participants were 5 with four men and one woman and taking into account the effectiveness of the sequence, we separated the participants in two and made them assembly the types of bed in opposite order.

4.2 Method of Analysis

We realized the same analysis as for the first experiment.

Also, we categorized the process of work in 12 processes for every video recordings.

4.3 Experiment Results

The recorded work analysis results are represented in Fig. 8. To show the relation to the time, we choose to represent only results for one person.

Fig. 8.

Comparison of required time for each process by type of cardboard beds

Overall, the new prototype is completed in a shorter required time and in particular processes like tapping both side of the boxes and inserting them in the sleeves dramatically become shorter.

4.4 Discussion

Based on Fig. 4, the new prototype is takes in comparison with the existing type generally less required time, as especially required worktime of tapping or unfolding the boxes is shorter, it can be assumed that with the number of the boxes handled decreasing and the work load also diminished.

On the other side, there are processes showing less improvement such as closing the lid or inserting the diagonal partition, for example, but the new prototype larger boxes are less easy to handle and it can be possible that thicker cardboard used to maintain the bed’s strength as the boxes got bigger made assembling the bed harder.

5 Conclusion

For the first experiment, it is usual to think that collaborative work will take a shorter time than individual work but with collaborative work, each process have a different work load and we found that waiting time between processes is more long than with individual work. Rather than the worker trying to work more efficiently, shorten worktime was associated to the reduction of waiting time. Therefore, we found that even with numerous worker, the effective way of shortening worktime was to do all the processes alone.

In the second experiment, we compared work between the existing type and the new prototype of bed using half the number of boxes while being the same bed size. The improved version permitted to cut down by 38 % the worktime. The deceased number of boxes and not their sizes was the reason for this shorten worktime.

In the shelters, there is a great possibility that hundreds of cardboard beds can be installed. As shorter worktime is extraordinary effective, hereafter we want to associate further design and work charge’s method improvements with the decrease of worktime in the assembly of the cardboard bed.