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NCHRP Web-Only Document 250: Use of Automated Machine Guidance within the Transportation Industry David White, Charles Jahren, Pavana Vennapusa, Caroline Westort, Ahmad Alhasan, Yelda Turkan, and Fangyu Guo Iowa State University Ames, Iowa John Hannon and Adam Dubree The University of Southern Mississippi Hattiesburg, Mississippi Tulio Sulbaran University of Texas at Austin Austin, Texas Contractorâs Final Report for NCHRP Project 10-77 Submitted August 2017 ACKNOWLEDGMENT This work was sponsored by the American Association of State Highway and Transportation Officials (AASHTO), in cooperation with the Federal Highway Administration, and was conducted in the National Cooperative Highway Research Program (NCHRP), which is administered by the Transportation Research Board (TRB) of the National Academies of Sciences, Engineering, and Medicine. COPYRIGHT INFORMATION Authors herein are responsible for the authenticity of their materials and for obtaining written permissions from publishers or persons who own the copyright to any previously published or copyrighted material used herein. Cooperative Research Programs (CRP) grants permission to reproduce material in this publication for classroom and not-for-profit purposes. Permission is given with the understanding that none of the material will be used to imply TRB, AASHTO, FAA, FHWA, FMCSA, FRA, FTA, Office of the Assistant Secretary for Research and Technology, PHMSA, or TDC endorsement of a particular product, method, or practice. It is expected that those reproducing the material in this document for educational and not-for-profit uses will give appropriate acknowledgment of the source of any reprinted or reproduced material. For other uses of the material, request permission from CRP. DISCLAIMER The opinions and conclusions expressed or implied in this report are those of the researchers who performed the research. They are not necessarily those of the Transportation Research Board; the National Academies of Sciences, Engineering, and Medicine; or the program sponsors. The information contained in this document was taken directly from the submission of the author(s). This material has not been edited by TRB.
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NCHRP Project 10-77 iv CONTENTS CONTENTS ................................................................................................................................................. iv LIST OF FIGURES ..................................................................................................................................... ix LIST OF TABLES ....................................................................................................................................... xi ACKNOWLEDGMENTS ......................................................................................................................... xiii SUMMARY ................................................................................................................................................. xi AMG Workflow Processes ............................................................................................................. xi AMG Information Review .............................................................................................................. xi Survey Outcomes ........................................................................................................................... xii Legal Barriers................................................................................................................................. xii AMG Training Opportunities ....................................................................................................... xiii Best Practices and Challenges for Design Model Development ................................................... xiii Impact of AMG on Earthwork Quantities ..................................................................................... xiii Accuracy of AMG Process ........................................................................................................... xiii AMG Guide Specification ............................................................................................................ xiv The Future of AMG ...................................................................................................................... xiv CHAPTER 1: Introduction ........................................................................................................................... 1 Problem Statement ........................................................................................................................... 1 Research Objectives and Scope ....................................................................................................... 1 Research Approach .......................................................................................................................... 2 Report Organization ......................................................................................................................... 4 CHAPTER 2: Basic AMG Workflow Processes .......................................................................................... 6 Surveying Workflow ........................................................................................................................ 6 Select Reference System ..................................................................................................... 6 Establish Project Control-Monumentation and Metadata ................................................... 7 Develop Work Plan to Locate Terrain and Features ........................................................... 7 Execute Work Plan ............................................................................................................. 7 Fuse Data ............................................................................................................................ 7 Check Quality ..................................................................................................................... 7 Design Process ................................................................................................................................. 8 Design Office Conceptualization........................................................................................ 9 Surveying ............................................................................................................................ 9 Designers Develop Drawings or Models ............................................................................ 9 Project Letting and Award .................................................................................................. 9 Contractor Data Preparation............................................................................................................ 10 Decisions about Using AMG ............................................................................................ 10 Data Preparation for 3D Conversion ................................................................................. 11 Conversion to Hardware Application Format as Necessary ............................................. 11 Model Quality Control ...................................................................................................... 11 Minor Additional Data Preparation by Field Personnel as Necessary .............................. 11 Verify Existing Control Points ......................................................................................... 12 Synchronize Field Control and Design Control ................................................................ 12 Customize Model for Operator Use .................................................................................. 13 Implement Model into AMG-Ready Equipment .............................................................. 14
NCHRP Project 10-77 v Overall AMG Processes ................................................................................................................. 14 Execute AMG Work Plan ................................................................................................. 14 Quality Control ................................................................................................................. 14 CHAPTER 3: AMG Information and Lexicon ........................................................................................... 17 AMG Project Bibliography Tool ................................................................................................... 17 Information and Literature Sources ............................................................................................... 17 Search Engines .................................................................................................................. 17 Conferences and Workshops............................................................................................. 18 AMG Project Bibliography Organization and Topics ................................................................... 18 Dissemination ................................................................................................................................ 20 AMG Lexicon ................................................................................................................................ 20 CHAPTER 4: Key Stakeholder Survey Results ......................................................................................... 24 Methodology .................................................................................................................................. 24 Survey Planning and Question Development ................................................................... 24 Monitoring ........................................................................................................................ 25 Assessment ........................................................................................................................ 26 Respondent Demographics ............................................................................................................ 26 Contractors ........................................................................................................................ 26 Responding Transportation Agencies ............................................................................... 27 Software and Hardware Vendors ...................................................................................... 27 Heavy Equipment Vendors ............................................................................................... 28 Training and Educational Organizations .......................................................................... 28 Barriers to AMG Adoption ............................................................................................................ 28 Contractor Perspective ...................................................................................................... 28 Agency Perspective ........................................................................................................... 29 DTM Creation, Use, and Sharing .................................................................................................. 29 Contractor Perspective ...................................................................................................... 29 Agency Designer Perspective ........................................................................................... 30 Agency Planner and Surveyor Perspective ....................................................................... 30 Agency Procurement and Construction Function Perspective .......................................... 30 AMG Quality Control and Accuracy ............................................................................................. 31 Topographical Data and Collection .................................................................................. 31 Digital Terrain Modeling .................................................................................................. 32 AMG Accuracy ................................................................................................................. 32 QA/QC .............................................................................................................................. 33 EED and Data Formats .................................................................................................................. 34 AMG Legal Aspects ...................................................................................................................... 35 AMG Education and Training ....................................................................................................... 36 Perceived Risks of AMG ............................................................................................................... 37 Perceived Benefits of AMG ........................................................................................................... 38 CHAPTER 5: Legal Aspects of AMG Data ............................................................................................... 41 Owner/Agency Reluctance to Share EED with Contractors .......................................................... 41 Warranty of Design ........................................................................................................................ 41 Copyrights ...................................................................................................................................... 45 Definition of Functional Roles ....................................................................................................... 45 Approval and Certification of Design Intent .................................................................... 46 Definition of Design, Engineering, and Surveying ........................................................... 47 Responsible Charge .......................................................................................................... 50 Survey Results ............................................................................................................................... 51 Agency Procurement and Construction Function Perspective .......................................... 53
NCHRP Project 10-77 vi Agency Designer Perspective ........................................................................................... 54 Legal Research ............................................................................................................................... 55 Literature Review ............................................................................................................. 55 Legal Survey ..................................................................................................................... 55 Text String Searches ......................................................................................................... 55 Sample String: Liability Waiver + Construction + Contracts + Public Works + Enforceability.................................................................................................................... 56 TRB Legal Committees .................................................................................................... 56 Summary of Legal Aspects of AMG Data ..................................................................................... 56 CHAPTER 6: AMG Education and Training ............................................................................................. 58 The Importance of Education and Training for AMG ................................................................... 58 AMG Education and Training Delivery Methods.......................................................................... 59 Sources of Education and Training for AMG ................................................................................ 60 Surveying and Positioning Hardware ............................................................................... 60 Modeling Software ........................................................................................................... 61 AMG in Educational Institutions ...................................................................................... 64 Educational and Training Opportunities Summary ....................................................................... 65 CHAPTER 7: Best Practices for AMG Design Model Development ......................................................... 67 The Importance of 3D Modeling ................................................................................................... 67 Initial Planning for Modeling ........................................................................................................ 67 Philosophy of Building a BIM-Type 3D Model ............................................................... 67 Overall Spatial Control ..................................................................................................... 68 Data Transfer (Inputs and Outputs) .................................................................................. 69 Selection of Technology for Spatial Data Collection for Existing Terrain and Features . 70 Consider Tradeoffs ........................................................................................................... 71 General Procedure for Developing Models ................................................................................... 72 Reference CAD Standards ................................................................................................ 73 Add Horizontal and Vertical Alignments ......................................................................... 73 Create Typical Sections from Templates .......................................................................... 73 Generate Design Surface Model ....................................................................................... 74 Check Design Surface ....................................................................................................... 74 Merge Design Surface and Preconstruction Surface ......................................................... 74 Conduct Necessary Manual Design in Complicated Areas .............................................. 74 Perform Constructability Review ..................................................................................... 74 Generate Final Files .......................................................................................................... 75 3D Model Special Considerations ................................................................................................. 75 Contractor Use of 3D Modeling .................................................................................................... 76 Summary of Data Transfer Methods .............................................................................................. 78 Design Model Development Best Practices Summary................................................................... 79 Areas for Further Study.................................................................................................................. 79 CHAPTER 8: Impact of AMG on Earthwork Quantities ........................................................................... 81 Background .................................................................................................................................... 81 Survey Responses and Previous Case Studies ............................................................................... 81 Survey Responses on the Use of DTMs for Estimation .................................................... 81 Impact of AMG on Productivity Gain and Cost Savings.................................................. 82 Cost Savings Model .......................................................................................................... 85 Earthwork Quantity Computation and Measurement .................................................................... 87 Accuracy of DTMs ........................................................................................................... 87 Computation of Earthwork Quantities .............................................................................. 92 Model Enhancement for Construction Purposes ............................................................... 93
NCHRP Project 10-77 vii Model Conversion to QA/QC Format ............................................................................... 93 Impact on Earthworks Summary .................................................................................................... 93 CHAPTER 9: Accuracy of AMG Processes ............................................................................................... 95 Accuracy Review â AMG Workshop ............................................................................................ 95 Variables That Influence the Accuracy of AMG Processes .......................................................... 96 Position Measurement Technologies ................................................................................ 96 Construction Process and Human Errors ........................................................................ 100 AMG Control for Single Phase versus Multiple Phases of Project ................................ 101 Quantitative Evaluation of Accuracy ........................................................................................... 101 Statistical Data Analyses Approach ................................................................................ 101 Experimental Test Results .............................................................................................. 102 Accuracy of AMG Summary ....................................................................................................... 107 CHAPTER 10: AMG Implementation and Guidelines Specifications ..................................................... 109 AMG Specification Assessment .................................................................................................. 110 AMG Guide Specification Tool ................................................................................................... 112 Checklist of QC/QA Factors ........................................................................................................ 122 Initial Data Collection to Develop DTMs ....................................................................... 122 Model Development for Design Purposes ...................................................................... 122 Model Enhancement for Construction Purposes............................................................. 123 Manipulation of AMG Files for Construction Operations .............................................. 123 Manipulation of AMG Files for QA/QC ........................................................................ 123 CHAPTER 11: Future of AMG in Infrastrucutre Construction ................................................................ 125 Introduction .................................................................................................................................. 125 Emerging AMG Technologies ..................................................................................................... 125 The Future AMG Professional ..................................................................................................... 134 Data, Standardization, and Interoperability ................................................................................. 135 AMG in the Future: Concept for Land Drones ............................................................................ 136 AMG Contribution to Sustainability ............................................................................................ 138 Conclusions .................................................................................................................................. 138 CHAPTER 12: Summary and Conclusions............................................................................................... 140 AMG Workshop .......................................................................................................................... 140 AMG Workflow Processes .......................................................................................................... 141 Information Review ..................................................................................................................... 141 Survey Outcomes ......................................................................................................................... 141 Legal Barriers............................................................................................................................... 142 AMG Training Opportunities ...................................................................................................... 143 Development of Design Models â Best Practices......................................................................... 143 Impact of AMG on Earthwork Quantities .................................................................................... 144 Accuracy of AMG Process .......................................................................................................... 144 Guide Specifications and Implmentation ..................................................................................... 145 Future of AMG ............................................................................................................................ 146 REFERENCES ............................................................................................................................ 147 ABBREVIATIONS, ACRONYMS, INITIALISMS, AND SYMBOLS .................................................. 151 APPENDIX A: AMG Workshop Report APPENDIX B: Annotated Bibliography
NCHRP Project 10-77 viii APPENDIX C: AMG Specifications in the United States APPENDIX D: Detailed Survey Outcomes
NCHRP Project 10-77 ix LIST OF FIGURES Figure 1-1. AMG Applications involving (a) Three-Dimensional (3D) Design and (b) Application of AMG in Earthwork Grading (images curtesy of Iowa DOT and Caterpillar) ................................. 1 Figure 2-1. Elements of the AMG Workflow Processes ............................................................................... 6 Figure 2-2. Survey Preparation Workflow Processes ................................................................................... 8 Figure 2-3. Design Workflow Processes ..................................................................................................... 10 Figure 2-4. Contractor Data Preparation Workflow Processes ................................................................... 13 Figure 2-5(a). Overall AMG Workflow Processes ..................................................................................... 15 Figure 2-5(b). Contractor Documentation Subset of Overall AMG Workflow Processes ......................... 16 Figure 4-1. Transportation Agency Responses by U.S. State ..................................................................... 27 Figure 4-2. File Types of EED Exchanged Across AMG Functions .......................................................... 35 Figure 5-1. Statements from Delaware DOT (DelDOT)âs âRelease for Delivery of Documents in Electronic Form to a Contractorâ ................................................................................................... 43 Figure 5-2. Statements from California DOT (Caltrans) states, in a non-standard special provision for District 11. ..................................................................................................................................... 43 Figure 5-3. Statements from Iowa DOT, in âDevelopmental Specifications for Global Positioning System Machine Control Gradingâ ............................................................................................................ 44 Figure 5-4. Statements from the Indiana DOT (INDOT) Draft Specification for allowing Stakeless Excavation on a Highway Contract, Section 105.08. .................................................................... 44 Figure 5-5. Statement from California DOT (Caltrans) states, in a non-standard special provision for District 11. ..................................................................................................................................... 44 Figure 5-6. Statements from the North Carolina Board of Examiners for Engineers and Surveyors, 21 NCAC 56.1103, Standard Certification Requirements. ................................................................. 46 Figure 5-7. Statements from the Florida Board of Professional Engineers, 61G15-23.003 Procedures for Signing and Sealing Electronically Transmitted Plans, Specifications, Reports or Other Documents. .................................................................................................................................... 47 Figure 5-8. Statements from the Board for Professional Engineers and Land Surveyors, State of California, Clarification Regarding the use of Global Positioning System Equipment by Unlicensed Individuals, November 21, 2006. ................................................................................ 48 Figure 5-9. Comments from a surveying professional in a trade publication (see Harry, 2007) ................ 49 Figure 5-10. Professional engineer reports in a trade publication concerns about North Carolinaâs interpretation regarding DTM detailing (see Harry, 2007) ............................................................ 50 Figure 5-11. Statements from surveying profession (see Joseph, 2007) ..................................................... 50 Figure 5-12. Comments from Harry (2007) considering issues of accountability and liability .................. 50 Figure 5-13. Comments from professional surveyor has expressed this phenomenon in a trade publication (see Harry, 2007) ........................................................................................................................... 51 Figure 7-1. 2D vs. 3D Data Transfer .......................................................................................................... 70 Figure 7-2. Flowchart for 3D Model Development Procedure ................................................................... 72 Figure 7-3. File Types of EED Exchanged Across AMG Functions .......................................................... 78 Figure 8-1. Survey Responses by Contractors on the Use of DTMs .......................................................... 82 Figure 8-2. Survey Responses by Contractors and Vendors and Productivity Gain and Potential Cost Savings using AMG, and Data obtained from Field Case Studies ................................................ 83 Figure 8-3. Estimated Percent Cost Savings on a Subbase Fine Grading Project using AMG................... 87 Figure 8-4. Elevation Data points for Developing DTM over a 540 m2 Area: (a) 78 Data Points; (b) 38 Data Points; and (c) 11 Data Points ............................................................................................... 89 Figure 8-5. Picture of the Area with Elevation Data ................................................................................... 89 Figure 8-6. DTMs of a 540m2 Area using 78 Elevation Data Points using Different Interpolation Methods: (a) Inverse Distance to a Power; (b) Kriging; (c) Local Polynomial; (d) Minimum Curvature; (e) Nearest Neighbor; (f) Triangulated Irregular Network (TIN) ................................ 90 Figure 8-7. DTMs of a 540m2 Area using 38 Elevation Data Points using Different Interpolation Methods: (a) Inverse Distance to a Power; (b) Kriging; (c) Local Polynomial; (d) Minimum
NCHRP Project 10-77 x Curvature; (e) Nearest Neighbor; (f) Triangulated Irregular Network (TIN) ................................ 90 Figure 8-8. DTMs of a 540m2 Area using 11 Elevation Data Points using Different Interpolation Methods: (a) Inverse Distance to a Power; (b) Kriging; (c) Local Polynomial; (d) Minimum Curvature; (e) Nearest Neighbor; (f) Triangulated Irregular Network (TIN) ................................ 91 Figure 9-1. Conceptual Illustration of Comparison between Pavement Layer Thickness with Uniform Support Conditions and Non-Uniform Support Conditions Using AMG .................................... 101 Figure 9-2. CS74 roller setup with padfoot shell kit and RTK-GPS on Project 1 with sloping uneven ground conditions a grading project ............................................................................................ 103 Figure 9-3. CS563E smooth drum roller setup with RTK-GPS on Project 2 with relatively flat grade over gravel road ................................................................................................................................... 103 Figure 9-4. CS74 smooth drum roller setup with SBAS-GPS on Project 3 with sloping gravel road ...... 104 Figure 9-5. CS56 smooth drum roller setup with RTK-GPS on Project 2 with relatively flat grade over gravel road ................................................................................................................................... 105 Figure 11-1 Example 3D Design Software used to Generate 2D Cross Sections (courtesy Brian Smith, Iowa DOT) ................................................................................................................................... 125 Figure 11-2 Example of Color-Coded Plans (a) Plan View (b) Alignment with Geotechnical Information (courtesy Brian Smith, Iowa DOT). ............................................................................................. 126 Figure 11-3 Example of Black and White versus Color Design Sheet with Notes (courtesy Brian Smith, Iowa DOT). .................................................................................................................................. 127 Figure 11-4. Laser Scan Images showing (a) Integrated Digital Color Photo with x, y, z Geospatial Coordinates (b) Rendering for Volume Calculations, and (c) Digital Image with x, y, z Coordinates and Calculated 2 ft Contour Intervals (images courtesy CEER, Iowa State University). .................................................................................................................................. 128 Figure 11-5. LIDAR Application to (a) Map Corridor, and (b) Define Larger Area Flooding (images courtesy of Iowa DOT). ............................................................................................................... 129 Figure 11-6. Examples of 3D Surface Renderings showing Complex Geometries (courtesy of McAnich Corporation and Iowa DOT) ........................................................................................................ 130 Figure 11-7. 3D Rendering and Visualization of Project (courtesy Brian Smith, Iowa DOT) ................. 130 Figure 11-8. Simulated Construction Environment that Allows User to Operate Machine (image courtesy X,Y,Z Solutions) .......................................................................................................................... 131 Figure 11-9. Inexpensive UAV with High Definition Camera. ................................................................ 131 Figure 11-10. Integrated Data Analytics and Mobile Viewing (image courtesy of AGTEK). ................. 132 Figure 11-11. Intelligent Compaction data as viewed from On-line Viewer (image courtesy of Trimble).132 Figure 11-12. Examples of AMG Machine Application. .......................................................................... 133 Figure 11-13. AMG Application for PCC Paving (a) Site Level Setup and Equipment, and (b) PCC Stringless Paving Operations (images courtesy of Dale Harrington). ......................................... 134 Figure 11-14. Autonomous Mars Rover (http://news.nationalgeographic.com/news/2012/08/120806- mars-landing-curiosity-rover-nasa-jpl-science/) .......................................................................... 136
NCHRP Project 10-77 xi LIST OF TABLES Table 1-1. Synthesized and Ranked Priorities â General Session from AMG Stakeholder Workshop ........ 3 Table 3-1. Categories and Subcategories of References in the AMG Project Bibliography ...................... 19 Table 3-2. Types of Information and Literature in the AMG Project Bibliography ................................... 19 Table 4-1. Survey Responses by Targeted Survey ..................................................................................... 26 Table 4-2. Contractor Survey Respondents by Industry Segment .............................................................. 27 Table 4-3. Training and Education Survey Respondents by Delivery Organization Type ......................... 28 Table 4-4. Contractor Reasons for Not Utilizing AMG .............................................................................. 29 Table 4-5. Surveyor and Planner Rankings of Surveying Technology Accuracies .................................... 31 Table 4-6. Important DTM Accuracy Factors Rated by Contractors, Agencies, and Software/Hardware Vendors .......................................................................................................................................... 32 Table 4-7. Factors contributing to EED Accuracy According to Software/Hardware Vendors ................. 32 Table 4-8. Important AMG Accuracy Factors Rated by Contractors, Agencies, and Software/Hardware Vendors .......................................................................................................................................... 32 Table 4-9. Important Equipment Accuracy Factors Rated by Contractors, Agencies, and Heavy Equipment Organizations ............................................................................................................... 34 Table 4-10. Respondents Reporting Claims or Arbitration Related to AMG ............................................. 36 Table 4-11. Contractor and Agency Opinions of Liability Exposure with EED Exchange ....................... 36 Table 4-12. Contractor and Agency Opinions of Sharing EED and Cooperation ...................................... 36 Table 4-13. Contractor Field Personnel Software Training ........................................................................ 36 Table 4-14. Contractor Field Personnel Hardware Training ....................................................................... 37 Table 4-15. Contractor Machine Operator Training ................................................................................... 37 Table 4-16. AMG Risk Factors rated by Contractors, Agencies, and Equipment Vendors ........................ 38 Table 4-17. Perceived AMG Benefits by Contractors, Agencies, and Equipment Vendors ....................... 39 Table 4-18. Comparison of Contractor and Equipment Vendor Productivity Gains with AMG ................ 40 Table 4-19. Comparison of Contractor and Equipment Vendor Cost Savings with AMG ......................... 40 Table 5-1. At What Contract Stage Should EED be Exchanged? ............................................................... 52 Table 5-2. At What Contract Stage is EED Exchanged? ............................................................................ 52 Table 5-3. Respondents Reporting Claims or Arbitration Related to AMG ............................................... 52 Table 5-4. Contractor and Agency Opinions of Liability Exposure with EED Exchange ......................... 53 Table 5-5. Contractor and Agency Opinions of Sharing EED and Cooperation ........................................ 53 Table 5-6. How Agencies Not Sharing EED Should Limit Liability ......................................................... 54 Table 5-7. How Agencies Currently Sharing EED Limit Liability ............................................................ 54 Table 5-8. Agency Designers Concern with Liability from Sharing EED ................................................. 55 Table 5-9. Search Engine Text String Generation ...................................................................................... 56 Table 6-1. Educational and Training Provided by Software Developers. ................................................... 62 Table 6-2. Educational and Training provided by hardware and equipment manufacturers and related organizations .................................................................................................................................. 63 Table 6-3. Offerings from Educational Institutions .................................................................................... 66 Table 7-1. Required Accuracy for Modeling (Taylor, 2010) ...................................................................... 68 Table 7-2. Recommended Pattern Line Spacing (Taylor, 2010) ................................................................ 74 Table 8-1. Comparison of Traditional String Line Control and Stringless AMG Approaches for PCC Paving (from Cable et al., 2009) .................................................................................................... 84 Table 8-2. Absolute Mean Error of Estimated Elevation Data Based on Cross-Validation Process using Different Interpolation Methods .................................................................................................... 91 Table 8-3. Absolute Mean Error of Estimated Elevation Data by Comparing Kriged DTM with 79 points with Different Interpolation Methods ............................................................................................ 92 Table 9-1. Various Sources of Errors Contributing to the Overall AMG Accuracy (2009 Workshop Findings) ........................................................................................................................................ 95 Table 9-2. Frequency of Errors and Suggested Detection/Mitigation Strategies ........................................ 97 Table 9-3. Summary of Different Position Measurement Technologies .................................................... 99
NCHRP Project 10-77 xii Table 9-4. Comparison of different types of construction machines (after Retscher 2002) ..................... 100 Table 9-5. Typical Two-Way ANOVA Table .......................................................................................... 102 Table 9-6. Summary of repeatability analysis results on GPS elevation measurements on three earthwork project sites with and without RTK-GPS mounted on roller compactors .................................... 106 Table 9-7. Summary of R&R analysis results on GPS elevation measurements to assess the influence of change in direction of travel ........................................................................................................ 106 Table 9-8. Example Qualitative Assessment matrix of Accuracy Factors for Various Application Categories .................................................................................................................................... 107 Table 10-1. Summary of AMG Specifications and Key Attributes .......................................................... 111 Table 10-2. AMG Guide Specification Tool ............................................................................................ 113
NCHRP Project 10-77 xiii ACKNOWLEDGMENTS The research reported herein was performed under NCHRP Project 10â77 by the Earthworks Engineering Research Center at Iowa State University and the University of Southern Mississippi. Caterpillar Inc. was a subcontractor for this study. The authors would like to thank the project panel and the expert contract group for providing timely feedback. Several representatives from industry participated in a workshop event and conference calls and contributed to the survey findings of this study. More than 500 individuals provided feedback during these Phase I research efforts.
NCHRP Project 10-77 xi SUMMARY Automated machine guidance (AMG) links sophisticated design software with construction equipment to direct the operations of construction machinery with a high level of precision, and improve the speed and accuracy of the construction process. AMG technology has the potential to improve the overall quality, safety, and efficiency of transportation project construction. This research project was undertaken to study AMG implementation barriers and develop strategies for effective implementation of AMG technology in construction operations. Early in the research effort, an expert contact group was established to obtain perspectives from agencies, contractors, designers, and equipment manufacturers. An AMG workshop was conducted to develop a list of capabilities that must exist and obstacles that must be overcome to facilitate seamless electronic data transferâfrom the initial surveying, to the development of digital terrain models (DTMs), through design and construction, to final inspection and verification. The synthesis from the workshop helped provide a framework and content for completing the research. Summarized here are some of the key findings from this research project. AMG WORKFLOW PROCESSES Integrating AMG into transportation projects involves complex decision-making and workflow processes, including selection of surveying methods and technologies, software design and engineering analytic tools, machine systems, sensor technologies, data interoperability and transfer mechanisms, and human-machine interaction during construction and training. A set of simplified workflow diagrams and narratives of processes and technologies have been provided by organizing the topics as follows: 1. Surveying preparation workflow processes, 2. Roadway design workflow processes, 3. Contractor data preparation workflow processes, and 4. Overall integrated AMG workflow processes. The accompanying narrative attempts to concisely describe the processes involved with the workflow steps first to establish a baseline for the remainder of the report, and, second, to appreciate that AMG is best positioned to succeed when survey, design, and construction processes are properly coordinated. Understanding these AMG workflow processes is also important for developing guide specifications for effectively implementing AMG where critical roles and responsibilities can be defined. In discussions with stakeholders in AMG processes, data interoperability was identified in virtually all the workflow processes as a key factor in providing an efficient AMG process. In the future, data interoperability will continue to be an area of desired AMG technology advancement. AMG INFORMATION REVIEW The research team constructed a searchable electronic library of information related to AMG and supporting technologies. The projectâs bibliography currently contains more than 370 documents that range from peer-reviewed academic papers to specifications to transportation agency directives to manufacturer specific videos and others. The use of AMG technology is relatively new, and our study confirmed that the AMG literature base is not as mature as that of more-established technologies and procedures. As such, academic papers accounted for only 28% of the information sources in the AMG project bibliography. Even though information on AMG does not appear to have a large base of formally published papers, significant information was garnered through AMG-specific and related websites and from slides from presentations at meetings held by transportation agencies, software and hardware vendors, and contractors. A detailed annotated bibliography and list of AMG specifications was generated from the information and literature review. In addition, a lexicon of terms used in AMG was developed and is reported herein and is used
NCHRP Project 10-77 xii throughout the report. One of the key outcomes from the information and literature review was that there is very limited independently studied information that quantifies AMG machine-level performance or site-level construction efficiency gains for AMG projects. These areas require more research in order to fully understand the benefits of using AMG and related technologies in construction processes. SURVEY OUTCOMES The project survey garnered information from a sample of all major AMG stakeholder groups, helping to define the current state of the industry. The project team developed separate survey questions for the various stakeholder groups, based on internal collaboration and the literature collected to date. The survey covered the following topics: ⢠Current computer-aided drafting (CAD) software capabilities ⢠Types of electronic files that are submitted to contractors (such as .dgn, .dwg, .dtm, .tin, and LandXML files) ⢠When these files are made available to the contractors (such as pre-bid or post-award) ⢠Equipment capabilities and reliability ⢠Perceived benefits and challenges regarding AMG processes More than 5,000 survey respondents were solicited. Key survey outcomes are presented in the report. The full survey report is provided as a separate Appendix. The analysis results are primarily descriptive statistics and provide new insights into the development of this newly emerged technology. LEGAL BARRIERS The use of AMG technology in construction contracting has created changes in business work processes and contract delivery processes, affecting all the contract stakeholders. Some legal mechanism is needed to bridge the implied design warranty concerns (Spearin doctrine) and the ability to include electronic engineered data (EED) as part of the contract documents. Currently, liability waivers and clauses are performing this function, in part, but they are yet to be tested in the courts. The work process changes, resulting in functional role changes, have proceeded faster than the regulatory and legal systems have accommodated. A standard definition of professional roles is needed across all of the state license boards, which would help define the âresponsible chargeâ of the various professional stakeholders. Results of this project should be communicated to the National Council of Examiners for Engineering and Surveying (NCEES) for consideration in the Model Law document (NCEES, 2009), which is intended to be used as a reference work in the preparation of amendments to existing legislation or in the preparation of newly proposed laws. The intent of NCEES in preparing this document is to present to the jurisdictions a sound and realistic guide that will provide greater uniformity of qualifications for licensure, to raise these qualifications to a higher level of accomplishment, and to simplify the interstate licensure of engineers and surveyors.â Defining professional roles will also require a standardized definition of EED, including what it is not to be used for. The Proposal for Use of EED in Construction created in 2008 by a joint Associated General Contractors (AGC) of America and Departments of Transportation (DOT) subcommittee does not address professional roles or duties, nor does it address the contractual context. The good news, according to the project surveys, is that despite the legal hurdles; those with AMG experience perceive that it improves the spirit of cooperation between the contract stakeholders, through improved constructability communications. The project surveys have also indicated that the perception of liability regarding the exchange of EED is quite low.
NCHRP Project 10-77 xiii AMG TRAINING OPPORTUNITIES Good training programs will be necessary for stakeholders to maintain productivity and accuracy on AMG projects. An especially critical need exists for training (and possibly certification) on 3D modeling and the use of project control points during construction. Currently, training is provided by various sources; however, no one source provides all of the training necessary for AMG. A considerable number of self-paced online opportunities are available, especially for learning about software. Meanwhile, hands-on, instructor-led opportunities exist predominately for equipment operation and using positioning hardware. Educational institutions are beginning to include AMG in their curriculums; however, educational goals are more general than training goals. Therefore, AMG stakeholders must continue to train personnel as new members are incorporated into their AMG teams. BEST PRACTICES AND CHALLENGES FOR DESIGN MODEL DEVELOPMENT The development of fully-integrated, electronic 3D models was more common for building design and construction projects than transportation projects for a variety of reasons. Recently, however software and hardware tools have been developed that have considerable capability and intelligence along with workflows and policies that support them. Therefore, electronic 3D models of transportation projects are appearing with levels of integration that rival those found in the building construction industry. Available online training tools strongly supplement more traditional face to face option and will further facilitate electronic transportation model development. Wise choices regarding data collection during the initial surveying activities are an important part of the effort to improve the development of transportation design models. Transportation corridors are often long enough so that the curvature of the earth and other effects that cannot be address in a strictly Cartesian coordinate system will come into play. However, proper reference to geodetic surveys and/or state plane coordinates during both initial and construction surveys will address some of the challenges of developing and using electronic transportation models. Modern survey tools, including the use of global positioning system (GPS) surveying are available to increase the efficiency and lower the cost of such surveys. IMPACT OF AMG ON EARTHWORK QUANTITIES Proper use of digital information for AMG can result in less confusion and more accuracy than traditional methods of earthwork pay item quantification and payment. Survey responses from contractors indicate that majority of the responding contractors are already using DTMs for estimating quantities, means and methods, constructability, quantity of the progress of work, and payment. Most of the equipment vendors indicated potential productivity gain of around 40% and potential cost savings of about 25 to 40% using AMG. On the other hand, most of the contractors indicated potential productivity gains of about 10 to 25% and potential cost savings of about 10 to 25% using AMG. The literature suggests productivity gain ranged from about 5 to 265% and cost savings ranged from about 10 to 68%, depending on the position measurement technology used and the application. Only a few case histories provide project specific productivity estimates for AMG for applications involving road construction, pipe trench excavation, and paving. A cost model is described in this report that relates productivity to cost savings. ACCURACY OF AMG PROCESS The accuracy of the AMG process is primarily influenced by three variables: position measurement technology, construction process, and human errors. These parameters are application- specific or machine-specific, and have not been thoroughly studied and or documented in the technical literature. The research team conducted interviews with various contractors to get feedback on various
NCHRP Project 10-77 xiv error detection and mitigation strategies. Survey results indicated that a majority (> 70%) of contractors, software/hardware vendors, and agencies who responded believe that the number of elevation data points used in creating the DTM is an important factor in the accuracy of the DTM. A grid of data points was analyzed using six different interpolation methods to determine the absolute mean error (calculated as the average of absolute value of the difference between the actual and the estimate value). Results show that the interpolation method and spatial density of data points are factors. A summary matrix was developed with attributes of accuracy, coverage range, measurement principle, and relative cost of various position measurement technologies that are typically used in construction applications. Laser, ultrasonic, robotic total station, GPS, augmented GPS, assisted GPS (via mobile phones), locata (pseudolites), and infrared laser technologies were studied. Typical precision requirements and vertical accuracy requirements for earthwork and paving equipment/operations are summarized from sources identified in the literature. AMG GUIDE SPECIFICATION As part of the research effort, specifications from several transportation authorities were collected. To compare the contents of the specifications, various attributes were identified and compared between the specifications. After reviewing all of the collected specifications, it was observed that although the layout of each specification was different, similar topics were addressed and similar language was used. After a critical review of the phrase and heading tables, the following six headings were identified to best characterize the specification language from all of the specification documents â general, liability, equipment, responsibilities, measurement, and payment. These headings were selected for inclusion in an AMG guide specification tool. To use the AMG guide specification tool, it would ideally be reviewed and discussed by agency design and contracting groups and provided to contractors for review and comments. The guide tool is formatted so that it can be printed, marked for items to include, marked to add additional items, and space for adding comments. THE FUTURE OF AMG Rapid technological developments are propelling AMG towards new capabilities that are radically expanding and shifting the roles and identities of traditional surveyors, design engineers, agencies, contractors, and equipment providers. New paradigms are emerging for conceptualizing sites, designing new and different projects, constructing projects, and ultimately using and maintaining them. The future of AMG is one that will likely be abundant with new technologies, with advanced software, improved data interoperability, and new autonomous machine capabilities. To fully benefit, these developments must be stewarded proactively by a broadly inclusive AMG owner-designer-surveyor- engineer-construction community. How this community should interact and work together is yet to be defined, but may require new models, training, and even development of new educational disciplines/professions. Whatever the future AMG landscape looks like, it will require planning and new ways of interaction to garner the full potential of this technology. New partnerships, research and development, and training across the AMG community will be key to accelerating AMG innovation. The concept for an AMG professional is introduced in this context. Also, building on discussion elsewhere in this report on the topic of data interoperability, future needs are presented. A futuristic description of an AMG land drone is also presented in the context of some of the technical challenges that exist in advancing AMG capabilities to yet an even higher level than exists today.
