Safety monitoring to prevent fall accidents at construction site


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Safety monitoring to prevent fall accidents at construction site

  1. 1. International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308(Print), ISSN 0976 – 6316(Online) Volume 4, Issue 2, March - April (2013), © IAEME353SAFETY MONITORING TO PREVENT FALL ACCIDENTS ATCONSTRUCTION SITE USING AUGMENTED REALITYPetcharat Limsupreeyarat1, Tanit Tongthong1, Nobuyoshi Yabuki21(Department of Civil Engineering, Chulalongkorn University, Bangkok, Thailand)2(Department of Civil Engineering, Chulalongkorn University, Bangkok, Thailand)3(Division of Sustainable Energy and Environmental Engineering, Osaka University, Osaka, Japan)ABSTRACTSafety monitoring is normally separated from the main construction processes andrelies on the site personnel’s knowledge and experiences. Most of project information ispresented based on a 2D paper format and is difficult to understand. The site personnel haveto convert the paper-based information and generate 3D mental pictures. They use theconverted information to track the safety measures, safety signs and workers in the actualconstruction environment. This task is tedious and burdensome. Therefore, this paperproposed the integrated and visualized system to assist the site personnel in safety monitoringby using Augmented Reality (AR) technology. This technology can provide the specifiedvirtual information and superimpose into the real world scene. The safety protection forpreventing fall accidents is focused on. The prototype system was developed and tested inboth laboratory and real environment. The demonstrated results show the feasibility toimplement the proposed system in real construction project which the supervising personnelcan easily inspect and control the specified safety measures, safety signs, and personalprotective equipment.Keywords: Augmented reality, construction safety, fall accident, safety monitoringI. INTRODUCTIONConstruction has its own characteristics that are different from the manufacturing.Tasks and activities are always performed in an open area and exhibit variation in thephysical environment. Many tasks and activities are performed high from the groundconditions. There is a potential for serious accidents in construction sites due to the followingcausations: many people are close together, many activities are unpredictable, and theINTERNATIONAL JOURNAL OF CIVIL ENGINEERING ANDTECHNOLOGY (IJCIET)ISSN 0976 – 6308 (Print)ISSN 0976 – 6316(Online)Volume 4, Issue 2, March - April (2013), pp. 353-368© IAEME: Impact Factor (2013): 5.3277 (Calculated by GISI)www.jifactor.comIJCIET© IAEME
  2. 2. International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308(Print), ISSN 0976 – 6316(Online) Volume 4, Issue 2, March - April (2013), © IAEME354tolerance of risk is traditionally quite high, making the frequency and impact of unplannedactivities very high [1]. According to the cause codes of accidents in the construction industryby OSHA, there are five basic cause codes, consisting of falls, being struck by an object,caught in/between equipment or material, electric shock, and others [2]. The statistics onoccupational injuries and fatalities then show that falls and being struck by a moving orflying/falling object are the top three accident causations in the construction industry [3]–[4].In order to avoid accidents caused by falls or falling objects, preventive strategies such asidentifying the potential hazards, proper selection and use of safety protection system,training in the workplace, and provision of adequate preventive equipment are necessary [5].In order to prevent accidents and improve the level of safety in construction, varioussafety management systems are implemented during project-execution phases. According to astudy of [6], safety management is the set of actions or procedures associated with health andsafety in the workplace. Three main tasks of safety management consist of hazardidentification, safety measure planning, and control. Not only these tasks, but safetyeducation and training are also other essential tasks for achieving a zero accident target.However, in order to support construction personnel and to enhance the efficiency of safetymanagement, potential tools such as information technology are required. Therefore, manyprevious studies have made an effort to suggest the implementation of informationtechnology in safety management processes.II. SAFETY MONITORINGAs mentioned above, the level of safety monitoring can be improved by implementingthe information technology, for example, reference [7] proposed automated monitoring andcontrol algorithms for detection of the guardrails in accordance with safety planning. The fallhazards from the activities and areas in which these activities are performed were focused on.The algorithms of the model were developed in a computer program written in VISUALBASIC (VB), AUTOCAD, and MS PROJECT. The outputs of this study showed that themodel can identify potential fall hazards and dangerous areas in real time and compare themwith the planning. Moreover, it can warn the site personnel regarding the existing safetymeasures that have been missed or removed.Reference [8] presented a real-time safety monitoring system which focused on thereduction of fatal accidents caused by falls. This system consisted of a mobile sensing device,transmitter sets and repeaters for sending the detected information to a receiver, and softwarefor interpreting the received information. In the experiment, when the workers entered adefined dangerous area, the system automatically received the data and transmitted theinformation to the main computer to inform the safety managers regarding hazardoussituations.From the eleven construction sites observation in Thailand, superintendents normallyinspected working conditions and identified hazards based on their knowledge andexperience. Shop drawings and safety checklists sometimes were applied. If the worker worepersonnel protective equipment, the superintendents did not mention inspecting or providingother safety measures. Most of the construction projects used their own checklist forms, suchas those for personnel protection equipment and safety system evaluation. However, theseforms contained rough details and were ineffective for monitoring safety at the constructionsite. Normally, the site personnel used safety checklists to inspect their construction sites onlyonce a week. Nevertheless, this technique was not effective. It did not provide enough
  3. 3. International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308(Print), ISSN 0976 – 6316(Online) Volume 4, Issue 2, March - April (2013), © IAEME355information for safety execution and communication among project participants. Moreover, themajority of the information is presented in a two-dimensional graphical or text-based paperformat. Construction personnel have to mentally interpret and understand the obtained projectinformation.One of the advance visualization technologies is Augmented Reality (AR) which isproperly applied for information-intensive tasks which deal with information access andcommunication [9]. This technology was deployed in many previous studies due to its potential[10]-[12]. Therefore, this paper which proposes the innovative and visualized system to assist thesupervising personnel in the safety monitoring process for preventing fall accidents atconstruction site, use the potential technology, called Augmented Reality.III. PROPOSED SYSTEM ARCHITECTUREThe ideas to improve the monitoring process came from existing tools and documentswhich were text based and rough description. To perform this task, it requires knowledge andexperience of site personnel to identify and track the safety protection system or personnelprotective equipment. The proposed system contained the purposes to assist the constructionpersonnel when they inspect the safety measures, signs, and workers at the actual constructionsites. Two important modules, which are monitoring module and augmented reality module, weredeveloped in the proposed system. Monitoring module consists of two following sub-moduleswhich are safe work area monitoring module and personal protection equipment module.Database for storing 3D safety measures, safety signs, and worker information are also created.The proposed system architecture is configured and shown in Fig. 1. This system providestangible safety information and combines it along with information about the current environmentby using augmented reality technology. The advantage of augmented reality is that visualizationof the virtual objects is superimposed with the actual environment in real time and at the reallocation.Fig.1 Proposed system architecture
  4. 4. International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308(Print), ISSN 0976 – 6316(Online) Volume 4, Issue 2, March - April (2013), © IAEME356The hardware components for developing this system consist of a laptop computerand a web camera. The functionalities of each hardware component are described in Table 1.Due to the specifications of Logitech B905, it was used in this study. The markers, which areblack square patterns, were prepared for tracking the process according to computer visionalgorithms. In order to develop the augmented reality application for the proposed system, thefollowing environments, Microsoft Visual Studio (C/C++ langage), ARToolKit [13],DSVideo, GLUT, OpenVRML, OpenCV, IrrKlang, Freetype, and Directx, were required andused. ARToolKit is a C and C++ language software library and is broadly used in academicstudies [14]–[15], for example, reference [16] presented the invisible height evaluationsystem which can be used in the design process of future building to preserve the goodlandscapes. This library allows programmers to easily develop augmented realityapplications. Moreover, it is low cost so that users can prepare only a simple web camera andprinted black square patterns. The ARToolKit uses computer vision techniques forcalculating the real camera position and orientation relative to marked cards, allowing theprogrammers to overlay virtual objects onto these marked cards.Table 1 Hardware componentsFunctionality Hardware component SpecificationsVideo capturing Web camera Logitech B905ApplicationprocessingLaptop Lenovo IdeaPad Y430Processor: Intel Core 2 Duo T5800/2.0GHzMemory: 3.0 GB/4.0 GB(max)Display type: 14.1 inch TFT active matrixGraphic processor: Intel GMA 4500MHDDynamic Video Memory Technology 5.0Audio: sound cardVideo output Laptop screenSound output Laptop speakerUser input Laptop keyboard andtouchpad (mouse isoptional)IV. 3D MODELS PREPARATIONNot only were computer graphics generated by using the OpenGL used in thisproposed system, but the 3D modeling created by other software was also applied. Accordingto the construction site survey, the supervising personnel produced the shop drawings ofsafety measures by hand sketching, as shown in Fig. 2. These drawings only present the topand side views of safety measures. In fact, the safety measure components comprise steelframes, platforms, and top guardrails. The details of safety measures such as material and sizeshould also be presented. 3D modeling is implemented to develop safety measures which areassigned to the location of working areas according to safety planning. Not only 3D models,but also 2D images are developed to represent the essential caution signs at the constructionsite. These virtual construction signs are arranged for the workplace, and the site personnelcan use the prototype system to inspect and compare them with real practices.The 3D models of safety measures were generated by using CAD software called“Autodesk Revit Architecture” according to the shop drawings. Currently, this software isone of the famous software for creating building information modeling (BIM) and a fully-parametric solid modeler. It can produce complex shapes. Fig. 3 shows an example of the 3Dsafety measures which were created by using the Autodesk Revit Architecture. The user can
  5. 5. International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308(Print), ISSN 0976 – 6316(Online) Volume 4, Issue 2, March - April (2013), © IAEME357visualize the 3D models from many viewpoints. After creating the 3D models, they wereexported from the Revit format (.rfa file) to the CAD format (.dwg file).Fig. 2 Example of shop drawing of safety measuresFig. 3 Example of a 3D model of a safety measure generated with CAD softwareThe exported 3D models were imported into the 3D software such as “Autodesk 3DMax.” This importing process was done in order to modify and add more information, suchas the color of the models and a description of the safety measures as shown in Fig. 4 and 5.Fig. 5 presents an example of the 3D safety measures of a housing project, which was asample of real experiment testing. The 3D safety measures were created based on theminimum requirements of Thailand’s laws and regulations. The height of the top handrail andlength of the guardrail were 0.95 m. and 3.40 m. respectively. Moreover, a middle guardrailand toe board were also created. In order to use these 3D models in the AR application, theyrequired to be converted into the Virtual Reality Modeling Language (VRML) format (.wrlfile). VRML is a text file format where vertices and edges for a 3D polygon can be specified,along with the surface color, shininess, transparency, and so on.
  6. 6. International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308(Print), ISSN 0976 – 6316(Online) Volume 4, Issue 2, March - April (2013), © IAEME358Fig. 4 Example of 3D model imported into Autodesk 3D MaxFig. 5 Example of 3D model with descriptionV. PROTOTYPE DEVELOPMENTAs mentioned above, monitoring and control are among the main tasks of safetymanagement. Therefore, this system provides a monitoring module for helping theconstruction personnel to effectively perform this task. The monitoring module was dividedinto the following sub-modules: working area monitoring and personal protection equipmentmonitoring, as shown in Fig. 6. The details of each sub-module are described as follows.Fig. 6 User interface of monitoring module
  7. 7. International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308(Print), ISSN 0976 – 6316(Online) Volume 4, Issue 2, March - April (2013), © IAEME3595.1 Sub-module of safe work area monitoringThe first sub-module of the monitoring module was safe work area monitoring, whichwas developed to assist the site personnel when they inspect safety at the construction site.This sub-module was separated into two applications: monitoring for safety measures andmonitoring for safety signs as presented in Fig. 7.In the first application, normally the construction personnel monitor the safetymeasures at the construction site by using simple checklists according to the safety plan.However, the safety measures are not specified in the checklists or drawings concerning type,number, and size for assisting the site personnel in monitoring. Hence, the idea for improvingthe monitoring process by providing efficient tools was initiated. The four steps fordeveloping the prototype application were done as shown in Fig. 8. In the preparation step,the 3D models of safety measures were created as described in the previous section.Simultaneously, the sets of markers were also prepared. Then text files containing the list ofmarkers and 3D models of safety measures were created and loaded into the prototypeapplication. Later, the application processes according to the ARToolKit steps and rendersthe 3D models of the safety measures for the markers in accordance with the defined list. Fig.9 presents the user interface of the safety measure monitoring where the user can press theAR display button to view the output result. Additionally, the layout of marker wasdisplayed, as shown in Fig. 10, after the user pressed the button to view it.Fig. 7 User interface of sub-module of safe work area monitoringAn example of an output window of safety measure monitoring is illustrated in Fig.11. In this figure, 3D models of guardrails were rendered with information, such as shape andsize. Due to the requirements of the laws and regulations, not only should guardrails beinstalled to protect against fall hazards, but toe boards should also be installed to preventfalling object hazards, as demonstrated in the example.
  8. 8. International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308(Print), ISSN 0976 – 6316(Online) Volume 4, Issue 2, March - April (2013), © IAEME360Fig. 8 Flowchart of application of safety measure monitoringFig. 9 user interface of safety measure monitoring
  9. 9. International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308(Print), ISSN 0976 – 6316(Online) Volume 4, Issue 2, March - April (2013), © IAEME361Fig. 10 Example of marker layout on the 2nd floor plan of buildingFig. 11 Example of output window for safety measure monitoringThe second application of the safe work area monitoring sub-module is safety signmonitoring. To prevent accidents at a construction site, providing safety measures are not theonly effective approach; providing safety signs also helps. As seen in the previous discussion,the safety signs should be monitored by the supervising personnel to ensure that safety signsare installed at the proper location to warn the involved personnel. These signs should beparticularly designated when safety planning is developed. Later, it is effortless for the safetyinspectors that check for and monitor unsafe conditions. Therefore, a prototype applicationwas developed for this purpose.
  10. 10. International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308(Print), ISSN 0976 – 6316(Online) Volume 4, Issue 2, March - April (2013), © IAEME362Similarly, four steps in developing the AR application for safety sign monitoring wereperformed as presented in Fig.12. At the beginning, 2D image files representing each safetysign were created in the preparation step. Each marker represented one image of a safety sign.After detecting the marker and calculating the camera transformation, the 2D image of safetysign was displayed in accordance with the pattern on the marker. The user interface forrunning this application is presented in Fig. 13. The prototype application rendered the outputwindow as shown in Fig. 14. In this figure, three safety sign images (dangerous area,construction area, and walkway) were displayed. After the safety inspectors see the virtualsafety signs, they can check the real safety signs in the area and also monitor the workers asto whether they performed the tasks as the safety signs recommended.Fig. 12 Flowchart of application for safety sign monitoringFig. 13 user interface of safety sign monitoring
  11. 11. International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308(Print), ISSN 0976 – 6316(Online) Volume 4, Issue 2, March - April (2013), © IAEME363Fig. 14 Example of output window for safety sign monitoring5.2 Sub-module of personal protective equipment monitoringPersonal protective equipment monitoring was the second sub-module of monitoringmodule developed for assisting the superintendents in monitoring the proper personalprotective equipment of the workers in the work areas. The workers can be instructed by thesupervisors to wear the appropriate equipment before starting or continuing their work. In thisprototype application, fall hazards when workers perform construction activities were mainlyfocused on.This application also consists of the following four steps: preparation, input, process,and output, as shown in Fig. 15. For the preparation step, markers and 2D images containingthe workers’ information were prepared as with other applications. Furthermore, a databasecontaining information on the individual worker, such as injury records, training course,current job and location, and required personal protective equipment for current job, wascreated by using MySQL Workbench. Afterwards, a text file containing the list of markerfiles and 2D image files were loaded while the database file was retrieved.The markers were printed out and installed on the workers’ clothes. The user interfaceof the personal protective equipment sub-module is presented in Fig. 16. The user couldupdate both marker file and database file by pressing the buttons in the interface. Theapplication processes for rendering the virtual information of the workers according toARToolKit steps were capturing the video input frame, detecting and identifying the markers,calculating camera transformation, and loading 2D images files and worker information intothe database file. Then, the output windows were displayed, as shown in Fig. 17 and Fig.18(a) to 18(d). Workers’ information, such as name, age, position, was also provided both inthe 2D image and the text information on the screen. The safety inspectors could compare thephoto of the worker and other information on the 2D image with the text information on thescreen to identify the worker.
  12. 12. International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308(Print), ISSN 0976 – 6316(Online) Volume 4, Issue 2, March - April (2013), © IAEME364Fig. 15 Flowchart of application for personal protective equipment monitoringFig. 16 User interface of personal protective equipment monitoring
  13. 13. International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308(Print), ISSN 0976 – 6316(Online) Volume 4, Issue 2, March - April (2013), © IAEME365Fig. 17 Example of output window for the sub-module of personal protection equipmentmonitoring(a) (b)(c) (d)Fig. 18 Example of output windows for presenting worker information
  14. 14. International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308(Print), ISSN 0976 – 6316(Online) Volume 4, Issue 2, March - April (2013), © IAEME366VI. TESTINGIn the laboratory testing, the outputs of the prototype applications, such as safetymeasure preparation and safety measure monitoring, were correctly rendered as expected.However, the proposed system intended to provide the virtual objects in a real world scene tosupport construction personnel in carrying out safety management at actual construction sites.Therefore, the testing of the function for presenting the virtual objects was carried out.The virtual objects were created as described in the previous section. The marker unitin the text file and the scale of the virtual objects were points of concern. The marker size,which used in the experiments, was 0.3 m. In Fig. 19, the guardrail with a toe boardcontaining information about the dimension was rendered in the output screen, and Fig. 20demonstrates two options for a guardrail on the stairway.Fig. 19 Example of 3D virtual guardrail with toe boardFig. 20 Examples of 3D virtual guardrails in the required position
  15. 15. International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308(Print), ISSN 0976 – 6316(Online) Volume 4, Issue 2, March - April (2013), © IAEME367VII. CONCLUSIONSDue to inherent hazards at the construction sites, safety monitoring is the importanttasks to prevent accidents. To perform this task, it requires knowledge and experience of sitepersonnel to identify and track the safety protection system or personnel protectiveequipment. The innovative and visualized system, which is developed in this study, aims toassist the site personnel to monitor working area and worker for preventing falling accidents.The advance visualization technology, named Augmented Reality, was implemented toprovide the virtual information which is superimposed in the real world scene. Two mainmodules in the proposed system consist of monitoring module and augmented reality module.In monitoring module, there are two following sub-modules: 1) safe work area monitoringand 2) personal protective equipment monitoring. The first sub-module presented the safetymeasures and safety signs which should be installed in the specified area. In the second sub-module, the worker information and required personal protective equipment for each workerare illustrated. This prototype system was tested in laboratory and real environment. Theresults show it is feasible to provide the required safety information and assist the sitepersonnel in the safety monitoring process.VIII. ACKNOWLEDGEMENTSThis research is supported by the Faculty Development Scholarship of theCommission on Higher Education of Thailand with collaboration of AUN/SEED-Net.REFERENCES[1] P. Fewings, Construction Project Management: an Integrated Approach (Taylor &Francis, London, 2005).[2] J. Hinze, C. Pederson, and J. Fredley, Identifying Root Causes of ConstructionInjuries. Journal of Construction Engineering and Management, 124(1), 1998, 67–71.[3] R. A. Haslam, et al., Contributing factors in construction accidents, Journal ofApplied Ergonomics, 36, 2005, 401-415.[4] K. Srinavin, Characteristics of accidents on construction work in Thailand andprevention guide, CIB World Building Congress ‘Construction for Development’, CapeTown, South Africa, 2007.[5] Janicak, C. A., Fall related deaths in the construction industry, Journal of SafetyResearch, 29(1), 1998, 35-42.[6] V. Benjaoran, and S. Bhokha, An integrated safety management with constructionmanagement using 4D CAD model, Journal of Safety Science, 48(3), 2009, 395–403.[7] R. Navon, and O. Kolton, Algorithms for automated monitoring and control of fallhazards, Journal of computing in civil engineering, 21(1), 2007, 21-28.[8] U. K. Lee, J. H. Kim, H. Cho, and K. I. Kang, Development of a mobile safetymonitoring system for construction sites, Journal of Automation in Construction, 18, 2009,258–264.[9] X., Wang, and P. S. Dunston, Compatibility issues in Augmented Reality Systems forAEC: An Experimental Prototype Study, Journal of Automation in Construction, 15, 2006,314-326
  16. 16. International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308(Print), ISSN 0976 – 6316(Online) Volume 4, Issue 2, March - April (2013), © IAEME368[10] A. Webster, S. Feiner, B. MacIntyre, W. Massie, and T. Krueger, Augmented realityin architectural construction, inspection, and renovation, Proc. ASCE Third Congress onComputing in Civil Engineering. Anaheim, California, USA, 1996, 913-919.[11] G. Schall, E. Mendez, and D. Schmalstieg, Virtual redlining for civil engineering inreal environments, IEEE International Symposium on Mixed and Augmented Reality,Cambridge, UK, 2008.[12] A. H.Behzadan, and V. R. Kamat, Interactive augmented reality visualization forimproved damage prevention and maintenance of underground infrastructure, ConstructionResearch Congress, 2009.[13] HIT Lab., ARToolkit[Online], Available from:[2009, November 20].[14] N. Yabuki, and Z. Li, Cooperative reinforcing bar arrangement and checking by usingaugmented reality, CDVE 2007, LNCS 4674, 2007, 50-57.[15] N. Ota, N. Yabuki, T. Fukuda, Development of an accurate positioning method foraugmented reality using multiple markers, Proc. of the international conference on computingin civil and building engineering – 2010, Nottingham, UK, 2010.[16] N. Yabuki, K. Miyashita, and T. Fukuda, An invisible height evaluation system forbuilding height regulation to preserve good landscapes using augmented reality, Journal ofAutomation in Construction, 20, 2011, 228-235.[17] Prof. P. B. Alappanavar, Ankeeta Bhujbal and Shantanu Deshmukh, “Location BasedServices using Augmented Reality”, International journal of Computer Engineering &Technology (IJCET), Volume 4, Issue 2, 2013, pp. 237 - 240, ISSN Print: 0976 – 6367, ISSNOnline: 0976 – 6375.[18] Shaik Abdul Khader Jeelani, Dr.J.Karthikeyan and Dr.Adel S.Aldosary, “PerformanceEvaluation of Design-Build (D-B) Projects with and without Agency ConstructionManagement”, International Journal of Civil Engineering & Technology (IJCIET), Volume 3,Issue 2, 2012, pp. 265 - 278, ISSN Print: 0976 – 6308, ISSN Online: 0976 – 6316.