A visual tool for accessibility study of pipeline maintenance during design
© Lee et al.; licensee Springer. 2014
Received: 30 December 2013
Accepted: 5 June 2014
Published: 27 September 2014
Pipeline maintenance is becoming an important issue in modern construction and building information model (BIM) research. An understanding of pipeline accessibility considerations in terms of operation and maintenance is essential for planning and management. Previous studies have highlighted the complexity of multi-pipes including mechanical, electrical and plumbing (MEP) pipelines and the importance of information visualization, but few have proposed a way to consider accessibility problems during operation and maintenance.
Therefore, this study develops a systematic method to evaluate accessibility with respect to pipeline maintenance. We first divided pipeline accessibility into three categories: (1) visual accessibility—the visibility for an inspector to view; (2) approachable accessibility—the difficulty for an inspector to approach; and (3) operational accessibility—the pipeline that can be operated by the inspectors. We created mathematical models and discussed the ergonomic details about each category. We then developed a user interface, VAO Checker, in which V, A and O stand for visual, approachable and operational respectively, to display visual information about pipeline accessibility. Through instantaneous analysis, the system visualizes the accessibility of the pipelines. We visually represent the intersection and union of these three categories to illustrate the varying accessibility of pipe elements.
A usability test was conducted to validate the system's effectiveness. The results of the usability analysis show that users have higher correctness when using VAO Checker than 2D plan drawing and 3D model, and they evaluate the performance of this tool better than 2D plan drawing.
Pipeline designers can benefit by using this tool to sketch a suitable traffic flow for engineers to investigate. Furthermore, the substantial amount of information saved in the layout database could be referenced for future optimization.
Pipeline design has become increasingly important in modern construction. Operation and maintenance requires consideration of accessibility in the design of the layout of plant pipelines. Previous research has noted that piping accounts for 20% of costs for the industry as a whole (Calixto et al. ) and over 50% of the total detail-design labor hours (Park and Storch ). All other activities of following detail design depend on piping and massive savings are achievable by utilizing good layout design and engineering practices.
Mechanical, electrical, and plumbing (MEP) pipes used to be supplemental facilities in construction. However, they have become necessary facilities, especially in nonresidential construction, such as hospitals, fire stations, and plants. Coordinating a MEP system is a tremendous challenge in engineering fields such as advanced technology, health care, and biochemistry industries (Khanzode et al. ). Knowing how to arrange MEP systems appropriately is one of the most crucial aspects of the design phase (Riley et al. ).
Maintenance is a crucial phase in these types of construction. Based on a statistics on expenses in a typical water treatment plant in year-2008, maintenance takes 15% possession of the expenses (Biehl and Inman ). Moreover, based on some European and U.S. case study, maintenance has remarkable impact on at least one of the environmental aspects (Junnila et al. ). A poorly designed pipeline layout design wastes space and materials. Moreover, it can cause difficulty or even danger during manipulation and management.
The literature reviewed for this study included findings and recommendations related to piping that can be categorized into three main groups: a pipe-routing algorithm, the integration of multi-pipes, and the visualization of pipeline design.
Earlier studies of pipe routing
Integration of multi-pipes
An industrial plant typically has more than one kind of pipeline. Feng et al. () indicated a large number of pipelines, multifarious design constraints, and numerous obstacles in layout complicate the design of a pipeline system (Feng et al. ). Recently, engineers have mainly used existing CAD software for design assistance, which has increased the problems associated with experts, such as complex operation, a long design cycle, and low efficiency. Some researchers advocated a new layout space model to reduce high complexity and design interference in the automated design of pipeline systems (Deliang and Huibiao ; Feng et al. ). Kim et al. () found the range and complexity of the constraints limits the possibility of automatic pipe route design, and demonstrated a more natural and effective representation for route optimization (Kim et al. ). Previous studies recognized the complexity in pipeline arrangement and proposed some methods to reduce it (Biehl and Inman ; Guirardello and Swaney ). However, in many instances the pipeline layout cannot be simplified, so the complexity should be taken into account.
Visualization regarding pipeline accessibility
Some researchers have begun noticing the utility of information visualization for construction purposes as a means of improving the data-rich, but information-poor, problems of the construction industry (Songer et al. ; Tsai et al. ; Tsai et al. ). Previous research focused on the visualization of construction data, noting how it can help identify potential causal relationships among construction data (Korde et al. ; Kuo et al. ; Russell et al. ). Gao et al. () investigated colored construction drawing, which can increase the efficiency and accuracy of communication between designers and contractors (Grootjans a). Chang et al. () and Chen et al. () suggested a systematic procedure to determine the most suitable colors for effectively presenting the construction information (Chang et al. ; Chen et al. ). This procedure includes the selection, evaluation, and testing of colors to ensure they match the meaning of the construction information with the cognition of the users. Wang () used the conception of visualization to develop an approach for assessing reachability of wheelchair users (Wang ). With reference to pipeline arrangement, Deliang and Huibiao () pointed out that visualization can help handle the detection and response to collisions between pipes and obstacles (Deliang and Huibiao ).
During the early stage of this research, we interviewed six experts to determine the requirements of pipeline design. They are all in the field of plant pipeline design, including three engineers from a construction company, two managers from a microelectronics corporation, and one executive officer from the Building Information Modeling (BIM) research center. After combining the opinion of experts with previous literature review, we mainly focused our research on pipeline accessibility during operation and maintenance, which is rarely discussed in previous studies.
We mainly focused on operation and maintenance. Pipeline accessibility is the key factor to effective maintenance as it determines how easily the engineers can stretch to the accessories related to pipelines, including equipment, meters, and valves. Engineers can sometimes see pipelines from a distance, but cannot approach them due to the obstacles in the way of the pipelines. In other cases, engineers cannot read the meters in detail or operate the valves without difficulty, because these parts are mounted too high. We seek an easy way to illustrate pipeline accessibility with a view to engineers benefiting from this intuitive tool during the construction cycle (i.e., design, operation, and maintenance).
Objective and scope
The aim of this study is to develop a method to assist decisions about pipeline maintenance. One major challenge of coordinating MEP multi-pipes is identifying the spatial conflicts between systems. Through instantaneous analysis, the system automatically produces visual information indicating how much pipe access the engineers can have. This tool allows users to view, explore, and interact with the pipeline information via a direct manipulation interface in order to identify the spatial accessibility in a more intuitive manner. The user can thus obtain a comprehensive understanding of pipeline maintenance.
We use a Venn diagrama, a diagram that shows all possible logical relations between different sets, to differentiate three categories of pipeline accessibility. We then apply each section of the diagram to different scenarios. We further develop mathematical models and discuss the ergonomic details about each different category.
Overall procedure of pipeline accessibility
Visual (V): determines how much of the pipe is directly visible for inspection.
Approachable (A): determines how far maintenance engineers can walk along the pipes.
Operational (O): checks how much of the pipes can be reached in order to operate valves or check surfaces.
Seven variations of intersection and union
V - A - O
Only visible, but not approachable and operable. This happens when obstacles and other pipes prevent engineers from accessing equipment and pipelines.
A - V - O
Only approachable, but not visible and operable. This happens when obstacles and other pipes block displays and controls.
O - V - A
Only operable, but not visible and approachable. Although remote control is possible, we did not consider this variation.
V ∩ A − O
Visible and approachable, but not operable. This happens when controls or valves are mounted too high, too low, or too far away to reach and operate.
V ∩ O − A
Operable and visible, but not approachable. The same as [C]. We did not consider this variation.
V ∩ O − V
Approachable and operable, but not visible. This happens when controls and valves are mounted behind the display, and engineers have to bend their arms to operate them. However, any blindness operation is not allowed in our assumption.
V ∩ A ∩ O
Visible, approachable, and operable—the ideal situation.
These three categories are expressed in a visual conception of information. We adopted the anthropometric data from the American Bureau of Shipping (The American Bureau of Shipping ) to build the model for accessibility analysis. We made some modifications by considering the physical differences between Americans and Taiwanese, because the first case would be a semiconductor fabrication plant in Taiwan.
Bounding box size for recommended walkway dimensions
One person traveling in an area with limited access
One person in unrestricted area, where two persons could pass
One person with a cart
Normal two-way traffic or any means of egress that leads to an entrance or exit
Corridor or passageway that serves as a required exit
Suitable range of field-of-view
Suitable field-of-view and vision range (multiple of H) for legible and visible levels
Suitable forward functional reach and heights (multiple of H) for precise and general controls
This study developed a system, VAO Checker, which integrated the user interface and visualization information as a tool, to implement the proposed methodology. The following sections describe the software used for the development environment and the system design.
This study used Microsoft Windows Presentation Foundation (WPF) for the display of the user interface. WPF was chosen because it allows programmers to easily unify multimedia data, and change the appearance or the function of display controls for customization. Furthermore, the WPF application functions by off-loading to graphics processing units (GPUs) rather than central processing units (CPUs), which facilitates smoother graphics and better performance (Nathan ).
The framework developed for the visualization information was based on the Microsoft XNA Game Studio 4.0. This tool assists the development of video games and the improvement of software management. XNA has ample performance for the development of 2D and 3D games. It offers users the capability to build the operating system and visual images with ease (Grootjans ; Miller and Johnson ).
In order to verify how VAO Checker could help users explore and understand relevant accessibility information, we conducted a usability test. We also solicited expert consultation to verify the usability and how the users can interact with the pipeline accessibility information.
Category of 10 accessibility problems
There were 30 participants in the usability test, 19 male and 11 female. Their ages ranged from 20 to 37 years old. We solicited participant from non-engineering background as well, because they might provide suggestion from different point of view. Among the participants, 27 participants are from a civil engineering background, 2 from a psychology background, and 1 from an economics background.
Results and discussion
An α level of 0.05 was used for all statistical tests and analysis, and we calculated the p-value between groups in analysis of variance (ANOVA), where p < 0.05 means statistically significant. The test results assessed how quickly and accurately participants performed the task when using different mediums. There is also an analysis of NASA-TLX score, which shows how the participants evaluated the ergonomics performance of each medium. They are summarized as follows:
Correctness: VAO ≧ 3D > 2D
Statistical analysis of correctness
Std. Deviation (%)
2D plan drawing
2D & 3D
2D & VAO
3D & VAO
Performance: 3D > VAO > 2D
Statistical analysis of performance
Std. Deviation (points)
2D plan drawing
2D & 3D
2D & VAO
3D & VAO
Findings from the result
Most of the participants have a background of civil engineering, and they can get on track quickly when they check 2D plan drawing or 3D model. Based on the observation during the usability test, participants would spend some time to get used to the user interface of VAO Checker, because it is a new tool for them. As a result, the average problem identification time of VAO Checker is longer than 2D plan drawing and 3D model.
However, in the analysis of correctness, the success rate of VAO Checker is the highest. This means, although users might spend more time when they first contact with the user interface of VAO Checker, they still can achieve the goal of high correctness. Some participants advised that in addition to the three categories of accessibility, VAO Checker should take more safety factors into consideration. They indicated that the section where steam is generated should be prohibited to pass through. Then, the path should bypass those areas.
In the analysis of performance, the NASA-TLX score of 3D model is slightly higher than VAO Checker. We also interviewed the participants about their feeling when they manipulated VAO Checker. Many of them pointed out that the manipulation of VAO Checker had a sense of reality, unlike 2D plan drawing. They could look around the environment, and perceive the size of equipment and pipelines. The visual effects made it like playing a game. However, because the viewing angle of VAO Checker is set as first person, they sometimes got confused with the direction in the virtual environment. On the contrary, the viewing angle of 3D model is set as third person, and they can identify the direction easily. That is the reason some participants evaluated the NASA-TLX score of 3D model higher.
Furthermore, many of the participants commented that another reason they got confused with the direction is the unfamiliarity with the overall pipeline design. VAO Checker would serve as a useful tool for the designers who are conscious of the design, and they would benefit from this tool to correct any design errors. They suggested that VAO Checker is suitable for planning a more complex environment, such as chiller machinery room. The sizes of pipelines are bigger, and there are more relevant systems. Formerly only experienced designers could plan a pipeline layout which is acceptable enough. Through VAO Checker, designers could save a lot of time in analyzing and planning.
Owing to the booming BIM industry, some participants supposed VAO Checker would be developed into an application-programming interface (API) of BIM related software. Construction companies or corporations are increasingly using BIM as a tool to integrate information from the fields of architecture, structural engineering, and MEP systems. If VAO Checker can be developed into an API, more pipeline designers and engineers can benefit by saving time and effort.
Despite the participants needed some time to be familiar with the manipulation interface of VAO Checker, they all agreed that they could identify the accessibility problems very easily via this tool, because it provided sufficient information for them to judge the level of pipeline accessibility. They expected the path generated from analysis of approachable accessibility could be used for inspection or judgment, and the engineers would have a certain understanding of pipeline maintenance of the entire environment if they could move along this path.
Unlike previous studies, in which few solutions have been offered to propose a way to consider pipeline accessibility through maintenance, our research emphasizes the importance of pipeline accessibility and makes efforts on the following sections:
A useful tool for pipeline designers and engineers
We have shown that VAO Checker serves as a useful system for pipeline designers and engineers during operation and maintenance. Designers can benefit by sketching a suitable traffic flow for the users' investigation. Engineers can obtain a comprehensive understanding of the pipeline maintenance with the aid of the interface and can identify spatial accessibility in a more intuitive manner.
Considering pipeline accessibility
Unlike previous studies, in which few, if any, solutions have been offered to propose a way to consider pipeline accessibility through operation and maintenance, our research emphasizes its importance.
Integration of information from multi-pipes
With regard to the complexity of multi-pipes, different kinds of pipes might have to be considered in terms of different levels of accessibility. We developed mathematical models about each different accessibility category and discussed the ergonomic details.
Enhancing comprehension via visualization
Given the importance of visualization for pipeline accessibility, we developed VAO Checker, which integrated the user interface and visualization information as a tool to provide users with complete information about pipeline accessibility.
Even though this research has made efforts on the pipeline accessibility, there are still some possibilities can be worked on in the future:
Number of levels divided for each accessibility category
Operational accessibility, for example, has more than one kind of controls, such as toggle switches, pushbuttons, and rotary controls. Each demands a different level of sophistication, and might need a different description for the mathematical model of operational accessibility. From the standpoint of plan amendments, VAO Checker could be much more practical tool if the analysis result can show the segmented and numerical degree of accessibility.
Optimization via operators
The system we propose uses computation to suggest a suitable path by considering approachable accessibility. It might become much more usable if the pipeline's designer can improve results through specific operators based on the designer's experience. Furthermore, the tremendous amount of information saved in the layout database might be referenced for future optimization.
Development of pipe assembly planning
The pipe-routing design still relies on designer's experience. We hope this system can be extended to pipe assembly planning areas for efficient implementation, which might lead to a process of automatic pipe routing. The pipeline arrangement will only become more complex in the future, and pipe assembly planning will help increase the effectiveness and efficiency of routing design.
This research developed a systematic method to evaluate the accessibility of pipeline maintenance. During the early stage of this research, we interviewed six experts to determine the requirements of pipeline design. After combining the opinion of experts with a literature review, we mainly focused our research on pipeline accessibility during operation and maintenance, which is rarely discussed in previous studies. We first divided pipeline accessibility into three categories, developed mathematical models, and discussed the ergonomic details of each different category. We then developed a system called VAO Checker, which integrated the user interface and visualization information as a tool to implement the proposed methodology. VAO Checker used a simple motion-planning algorithm to find a path with acceptable approachable accessibility, and programmed the mathematical models into visualization information indicating the visual and operational accessibility. We created an example case to validate the practicality of VAO Checker, and conducted a usability test to evaluate the effectiveness of this tool. The result showed that it is a useful system for pipeline designers and engineers. It considered the pipeline accessibility within multi-pipes and enhanced the spatial comprehension. The system can be further integrated into BIM software as an API, extended to pipe assembly planning areas, or even referenced for future optimization.
aLewis, Clarence Irving and Leibniz, Gottfried Wilhelm (1918). A survey of symbolic logic, University of California Press.
CH developed the methodology and the mathematical models, programmed VAO Checker, carried out the usability test, analyzed the results and drafted the manuscript. MH assisted the literature review and the usability test. SC offered suggestion and guidance to the research. All authors read and approved the final manuscript.
This research was supported in part by Taiwan's Ministry of Economic Affairs, under contract 101-EC-17-A-15-S1-223. The authors are grateful to Mr. Ching-Yang Kao and Mr. Ming-Fa Lin of United Microelectronics Corporation (UMC), Mr. Yuan-Fu Liao and Mr. Yi-Ti Tsai of CTCI Corporation, Mr. Chien-Chih Lai of L&K Engineering Corporation and Mr. Ching-Hsien Lee of Research Center for BIM, National Taiwan University for their kind support and assistance in this research. We like to express our appreciation to the interviewees of these corporations and organizations.
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