3D Engineered Models for Construction

3D Engineered Models for Construction
Part I - Introduction September 2012 Part 1 Introduction

What is 3D Modeling? Using a collection of intelligent computer objects that represent an original surface, in our case the design surface of a highway segment. The objects know their position in space and in some cases what they represent. The 3D engineered model for construction has lines, points, and surfaces representing a picture and each component has intelligence that knows when a change is made to a component. The elements know where they are in space, and they know how they're tied into each other. Given this arrangement, modelers are able to spin them around, turn them upside down, and move them. This maintains an accurate representation in 3D of the desired object – in our case a highway facility. Part 1 Introduction

Why 3D Modeling? To better understand the design and locate possible conflicts and/or errors in the design. One of the benefits of this approach is that the visual makes the representation more intuitive compared to a 2D model since additional features are seen. The model is a 3D representation of the actual highway facility or portions of it. It can be viewed and examined in this virtual environment prior to building it and as though it would be if you were actually building it. The intuitive observations can help avoid conflicts, clashes, and errors in the design stage. Part 1 Introduction

3D Transportation Model
Since this picture is an electronic representation of a 3D computer model, it is possible to use a computer mouse to spin and tilt this surface so it can be viewed better from various perspectives. This is possible because the lines and points have intelligence, that is they know where they are in space and in relation to each other. If this was an electronic drawing instead of a model, this would be the only view available. Although it has a 3D appearance, it would not be possible to tilt and spin the surface. Courtesy of Iowa DOT Part 1 Introduction

Another 3D Model Courtesy of Iowa DOT
This is another 3D model. The top picture is a plan view while the bottom picture is a perspective view. If you look carefully at the perspective view, you may notice the figure is composed of small triangles. Each of these triangles represents a small plane. Together the triangles create a surface called a ‘triangular, irregular network” (TIN) which conforms closely, but not perfectly, to the actual proposed surface. This brings up an important point about modeling. In making a model, a person develops a mathematical or physical entity that approximates a real situation sufficiently close, so that it is useful for the purpose intended. Although the real surface is not actually made up of triangles, these triangles are useful for representing this surface because it does so well enough for the purpose of earthmoving. The bottom picture is another example of a model that is both useful and has limitations. Courtesy of Iowa DOT Part 1 Introduction

3D Cartesian Coordinates
When 3D models are developed for transportation projects, they are built in a Cartesian coordinate system. Cartesian coordinate systems specify each point in a plane using a pair of numerical coordinates which have defined distances from perpendicular lines. This image shows an x, y, and z axis that points can be related to. Graphic courtesy of Curtis Clabaugh, WYDOT. Part 1 Introduction Graphic courtesy of Curtis Clabaugh, WYDOT

Mapping Capabilities If the model is used in construction, it must fit on the surface of the earth which is roughly spherical. This exposes one of the limitations of the model. Fortunately, calibration procedures are available to fit the Cartesian model to the surface of the earth. As long as the calibration procedure is done properly, the Cartesian nature of the model is not problematic. Graphic courtesy of Curtis Clabaugh, WYDOT. Part 1 Introduction Graphic courtesy of Curtis Clabaugh ,WYDOT

A High Level Benefit of 3D Modeling
Improves communication between the owner, consultant, contractor, prefabricators, and materials suppliers Working in 3D, models are more intuitive and can be used for various functions. One benefit of the 3D model is better communication across a variety of stakeholders, including designers, construction engineers, contractors, and the public. Image courtesy of FHWA. Image courtesy of FHWA Part 1 Introduction

What are Some General Benefits?
Easier to get stakeholder buy in Identify possible errors before construction Visualize subgrade and potential utility conflicts Benefits to highway construction are similar to those realized in Building Information Modeling (BIM) Some general benefits of 3D engineered models include: -Stakeholder buy in on the project and key elements. -Streamlining of information flow, paperless, stakeless construction. -Contractors are in the process of adopting the technology. The highway industry sees benefits of use, including early problem identification such as utility conflicts. -Benefits are similar to those previously realized in Building Information Modeling (BIM) such as clash detection. Part 1 Introduction

Top Benefits for Owners
Grade check 100% of constructed surface Locate as-built utilities on the fly Improved industry perception Material cost savings There are several benefits to project owners such as a State DOT. For example, instead of having cross sections every 50 feet, there are surfaces you can grade check against continuously and fairly close to built utilities. 3D models also improve industry perception by having a more detailed representation of the constructed facility. Additionally, the more accurate contractors are, the less potential for overruns on the project. For example, base materials under the pavement may be six inches thick. Contractors may put in an extra inch because of concerns with penalties for making it too thin. This represents almost 20% extra material over a large area that may result in many additional square yards. There are savings associated with reducing the amount of material a half an inch will still meeting the specification. 3D models allow for communication on such challenges before breaking ground. Photo courtesy of FHWA Virtual construction to assess issues and improve communication prior to breaking ground! Part 1 Introduction

Top Benefits for Contractors
Save labor of setting string line (paving) or stakes (grading) Stringless paving may limit need for traffic closures Increased productivity Increased efficiency Reduced labor costs Contractors have benefits as well. Using a 3D model, they can grade and pave without stakes and string lines. These field applications increase productivity and efficiency and save on labor costs. Contracting labor cost is a large cost and provides some risk in the project for cost overruns. Efficiencies in the project can help reduce risk ultimately providing a benefit for the contractor. Photo courtesy of FHWA. Photo courtesy of FHWA Part 1 Introduction

Top Benefits for A/E Firms
Identification of potential constructability issues earlier in the design process Better value to clients Improved accuracy in design Visual model verification provides design QC Architectural and Engineering (AE) firms also have benefits from using 3D models. Constructability issues can be seen in 3D before the contractor mobilizes the equipment. If design changes are needed, they can be accomplished earlier in the process and prior to construction, minimizing change orders and lower risk for all involved. Quality control also occurs earlier in that the 3D models represents the facility in an enhanced form over traditional 2D models. Image courtesy of FHWA. Image courtesy of FHWA Part 1 Introduction

Leaders in the Use of 3D Modeling Wisconsin DOT Iowa DOT
North Carolina DOT Caltrans Land developers Design-builders This slide lists a few leaders in 3D modeling and the use of various field technologies and applications. There are likely other leaders that are not included here – this is just a sample list. Some states began using 3D modeling because much work is done on a design-build basis where the contractor brings other stakeholders, such as architects and engineers, for a dialogue about beginning construction right away. The designer then starts setting up models that might initially be in 2D with just contour lines. The contractor will look at it and get started on the process of making it a 3D model and start to find cost efficiencies. This dialogue continues in all directions and once the contractor has a 3D model, they will plan for use of field strategies such as automatic machine guidance to save on costs. Part 1 Introduction

Other Functions 3D Models Support
Public outreach/marketing for projects Utilities – coordination and early issue identification 3D mapping and data storage Clash detection Earthwork quantities A lot of early innovation in 3D modeling started in land development from partnerships between contractors, designers, owners, and the public. Public outreach is a key component of this process, as the 3D model can help the public better understand project impacts. The 3D engineered model provides data storage capabilities in that it is essentially engineering data that can be used for additional purposes in the present and future. Clash detection is also a key component of the process. This idea started in Building Information Modeling in that piping, ductwork, and other potential conflict items can be viewed in the model above the ceiling tiles prior to construction. This also applies to highways in that utilities in the subgrade can be viewed prior to construction to allow for designing around existing utility infrastructure. Using field technologies, 3D modeling can also help with quality assurance and help evaluate earthwork quantities for payment to contractors. The 3D Engineering Model is a building block of the digital jobsite. 3D Engineered Models are a Building Block of the Digital Jobsite Part 1 Introduction

Challenges to Implementation
Time investment from 2D to 3D Project selection – what characteristics to look for Coordination across key stakeholders (contractor, owner, designers, suppliers, etc.) There is a time investment going from a 2D design shop to a 3D design shop. Some of the costs include training, time, and software. There is a considerable amount of training that is needed, and taking personnel away from other work will impact output. A researcher from Wisconsin estimated that it would take two years to make the transition. This transition will not occur in a short time and all at once. There may be pilot projects during this time that allow for lessons learned and additional data to benefit processes and provide for updates. Begin with a pilot project that has a good opportunity for success. There are coordination issues in getting 3D modeling to work well, as there is a need to send an electronic file from the surveyor to the designer and from the designer to the contractor and from the contractor back to the owner. Agreement is needed on what those files involve, how they are formatted, and how updates are documented. Part 1 Introduction

What Challenges Need Consideration?
Where does “designing” stop and where does “detailing” begin? What becomes the legal record of the design? Can a 3D model be part of the contract documents? Can electronic plans legally represent the design? Designers and professional engineers who sign and seal drawings will turn over their design to a contractor. There are questions as to who is responsible for certain portions of the design, such as the contractor making changes to the model that might impact design and create a need for a professional engineer seal. Another question lies in who is detailing and preparing the model for “plug and play” into a machine. Another question lies in whether or not an electronic model can be stamped by a licensed engineer. There are a some states where this practice is not permitted and others that allow it. Part 1 Introduction

Project Development Considerations
When 3D modeling becomes more fully implemented, it will be possible to start early in the design phase to build the 3D model. After a decision has been made to upgrade, replace, or build a facility, models can make data gathering more efficient. GIS databases can be used to plan initial surveys and to develop a list of important features to be located in the field. After the surveying and data gathering are complete, designers build the 3D model. When the model is complete, it can be passed on to the constructor who can use the model for planning, quantity checking, visualizing the work, and automatic machine guidance. QC and QA activities can be recorded on the model at their proper location. Upon completion of the project, the contractor can modify the model to reflect the as-built condition and the model can be retained by operations and maintenance personnel who can use the model to record maintenance and road condition information at the proper location. When the decision is made to rebuild, existing 3D models can be used for planning and design. At this point, the model can be cycled through another construction project. Part 1 Introduction

Plans and Evolution 2D plans with profile and cross-section
3D plans, electronic data files, and digital terrain models Traditionally, construction projects use 2D plans with profiles and cross sections. These cross sections provide design detail at specified locations throughout the horizontal construction project (i.e. every 50 feet). With 3D models, cross sections are not needed, as the digital terrain model will allow for evaluation of a portion of the project at any location along the horizontal alignment. 3D modeling allows the existing and proposed features to be seen geospatially. Part 1 Introduction

Limitations of 2D Plans in Construction
Human error in reading plans Conflicts are not readily apparent No surfaces, just cross-sections We traditionally design and build accurately only at cross-sections There are limitations with 2D plans in construction. Some of these limitations are alleviated by 3D models. In 2D, there can be human error in reading plans. Clash detection is a key benefit of 3D models, but in 2D conflicts are not as readily noticeable until they are discovered during construction. Surfaces provide for a more detailed representation in 3D of the facility. In 2D, cross sections and profiles must be referred to consistently and thus introduce greater potential for error. Using a 3D model, we now have the capability to design and build accurately everywhere in the horizontal alignment. Using a 3D model, we now have the capability to design and build accurately everywhere. Part 1 Introduction

Several years old, sometimes
Key Stakeholders and Process Elements In order for contractors to take advantage of automatic machine guidance, a 3D model of the constructed surfaces must be available. If a 2D design process is used as shown in the lower part of the diagram shown on this slide, the contractor must develop a 3D model, almost from scratch. If 3D modeling were used in the design, it might be desirable to transfer the model directly to the contractor as shown on top. Sometimes legal or other concerns may prevent this transfer. Also, in many jurisdictions, the legally binding design must be represented on paper. Under such circumstances, if 3D modeling is used, the designer develops the traditional plan, profile and cross section views by extracting them from the model and then setting them up in plan sheets that can be printed on paper. If this is the case, it is possible that the 3D model can be transferred over to the contractor with the understanding (usually enforced by a signed waiver) that the model is for information only and that any model that the contractor uses which is derived from designer’s 3D model must conform to the hard copy plans. Otherwise the contractor will have to use the 2D plans to develop the contractor’s model, as described earlier. Several years old, sometimes Part 1 Introduction

How is the Workflow Different
from 2D to 3D? Develop incremental detail of a virtual model by working continuously in a 3D environment Extract the traditional 2D contract plans and bid item quantities from the 3D design model Export 3D data files for construction and use of technology applications in the field The process depicted on this slide is very common. An experienced 3D modeler may incrementally develop a design. That is, they may start from scratch with a 3D model and gradually develop it into a fully detailed 3D model. When making the contract document, they will extract 2D contract drawings out of the 3D model and then get the item quantities and other things from the 3D model. Data can then be extracted and used in machine guidance and control in the field. Part 1 Introduction

What Activities Can the
Model Support? A data package can be developed from the 3D model to support Automated Machine Guidance/Automated Machine Control “Plug and Play” equivalent once package is input to machine The 3D model can support several different activities. In some cases, designers may not want to transfer that 3D model directly to the contractor. They will transfer the 2D drawings instead. They might be electronic 2D drawings, and the contractor has to build the model from there. That process can be fairly expensive. In other cases, designers do transfer 3D models or portions of the model directly to the contractor. If the contractor has to sign a waiver, they won't hold the designer responsible for mistakes in the 3D model and the official record will be the 2D drawing. Part 1 Introduction

What is Automated Machine
Guidance (AMG)? A process where design software and construction equipment are linked to direct the operation of machinery with a high level of precision, improving the speed and accuracy of the construction process. Automated Machine Guidance is one field technique that can be used based on data in the 3D model. A machine file is prepared and loaded into the main computer on an equipped bulldozer or paver. This file references locations that might have traditionally been documented and located using stakes and string lines. Part 1 Introduction

Bulldozer Using AMG The bulldozer in this picture is set up for automatic machine guidance. It carries the electronic model in its on-board computers. The location of the GPS antennas are known and the cutting edge elevation and position can be computed by calibrating the cutting edge to the antenna. The on-board computers calculate the difference between the current cutting edge location and that of the proposed surface. The difference is displayed graphically on the computer screen in the machine if the distance is large. If the distance is small, AMG can be used to position the blade automatically without human assistance. Photo courtesy of David White, Iowa State University. Part 1 Introduction Photo courtesy of David White , Iowa State University

What the Machine Sees This is a reminder of what the model might look like in the computer of the machine. Courtesy of Iowa DOT Part 1 Introduction

Types of Guidance Systems (Guidance Systems Evolution)
Stakes String Lines String Lines with Sensors Lasers GPS Total Stations Paving requires tighter Z tolerances, so a positioning system that is more accurate than GPS is used. In this picture, robotic total stations that are located on the right of way at known locations shoot the TPS prisms mounted on the paver. Radio signals send position data from the robotic total stations to the machine guidance system which steers the machine and positions the paving mold. Photos courtesy of FHWA. Part 1 Introduction Photos courtesy of FHWA

Using Stakes – Traditional Method
Provides visual guide/grade information Stakes set by surveyor Field personnel read stakes and guide machine operator Under the traditional method, surveyors locate points in the field and set stakes to help machine operators identify positions and ultimately final grades. Photo courtesy of FHWA. Photo courtesy of FHWA Part 1 Introduction

Using String Lines – Traditional Method
Allows for machine control along a non- level surface Line represents a design surface at a particular elevation In paving operations, string lines are placed along the edge of pavement to help guide a paving machine along the correct location. Photo courtesy of FHWA. Photo courtesy of FHWA Part 1 Introduction

Using Lasers/GPS Lasers are used for elevations
A light bar on the cutting edge of a grader allows for up/down positioning GPS can be used to determine X-Y coordinates and pinpoint a location Users need different accuracies (we need “survey” level accuracy for highway projects compared with lower accuracy for recreational use or mapping) Global positioning systems, or GPS, reference locations in x-y coordinates. That is, they lack elevation, but can pinpoint a location such as on a map for travel distances. Other systems, such as lasers, supplement GPS coordinates and help provide for elevations at points located using x-y coordinates. This ultimately helps us locate exact positions and elevations for grades, as an example. Part 1 Introduction

Automated Machine Control Applications
Scrapers, dozers, excavators, motor graders, milling machines, pavers Automated machine control applications can include use of scrapers, bulldozers, graders, milling machines, and pavers. By knowing elevations, we can construct a grade, mill to a certain depth, and pave with string lines. This provides for efficiencies including time savings and cost savings in the field. Photos courtesy of David White, Iowa State University. Photos courtesy of David White, Iowa State University Part 1 Introduction

Earthworks This bulldozer has two GPS antenna on masts above each corner of the bulldozer blade. This configuration has been patented by Trimble Navigation Ltd. A calibration process determines the offset from the antenna to the cutting edge and the on-board computer calculates the actual position of the corner of the cutting edge of the blade based on this offset. With RTK (real time kinematic) GPS, the X and Y measurements are more accurate than the Z measurement. However, the Z measurements with RTK GPS are sufficiently accurate for earthmoving. Photo courtesy of David White, Iowa State University. Photo courtesy of David White, Iowa State University Part 1 Introduction

Typical Concrete Paving Using AMG
This is an example of a concrete paver with AMG capability. The two pictures at the top and bottom show 3D paving surfaces and provide data to guide the paver using a stringless system. Image courtesy of Ed Jaselskis. Courtesy of Ed Jaselskis Part 1 Introduction

Typical Asphalt Paving Using AMG
Like concrete paving, 3D modeling and automatic machine guidance can be used for asphalt paving. Photo courtesy of David White, Iowa State University. Part 1 Introduction Photo courtesy of David White, Iowa State University

Grading This picture shows a road grader with GPS antenna mounted on the moldboard. In some cases, lasers are used for vertical positioning rather than GPS in order to achieve greater accuracy. Since the x and y measurements of GPS are relatively accurate, GPS measurements can be used for horizontal positioning while the lasers are used for vertical positioning. Note that the roller has only one GPS antenna. In the case of a roller, the GPS positioning data is likely only to be used to confirm the number of passes that the roller makes. Therefore, in this case, two antenna are not needed because it is not necessary to find the complete location of a cutting edge that is shaping the earth. Photo courtesy of David White, Iowa State University. Photo courtesy of David White, Iowa State University Part 1 Introduction

Case Study Colorado I-70 Project
The next few slides provide information on a case study from Colorado. Part 1 Introduction

Colorado DOT I-70: The Problem
Expansive Soils  Severe longitudinal undulations, rough ride, cracking Widely varying asphalt depths – average 15” Traditional mill/fill: consistent mill depth would maintain existing profile This project is on I-70 in the western portion of the state almost to the Utah border. In this area there is quite a bit of expansive soil that provided for challenges on this particular project. Over the years, paving, asphalt overlays, and the soil conditions have caused very severe longitudinal undulations, rough ride, and cracking. The infrastructure needed to be corrected and not just with the traditional mill and fill or mill and concrete overlay. That would have just simply maintained the existing profile which was not acceptable to begin with. So asphalt depths vary considerably out there. This is a rural setting, as can be seen in the picture. All these items provide for a great example of how 3D models and machine guidance and control can be of benefit. Photo courtesy of FHWA. Photo courtesy of FHWA Part 1 Introduction

CDOT I-70: The Process No initial CDOT survey  Contractor survey
Specs allowed for AMG for milling Short timeline  GPS survey – 5 passes at 25’ EB/WB CDOT used MicroStation InRoads optimization to create 3D model with milling depths to balance humps and dips If you look at the photo, this gentleman is driving an ATV. He is conducting a GPS survey. Since the vertical element of the Cartesian system is not particularly accurate, perhaps off by as much as plus or minus an inch, this can make a large impact on project costs if quantities are off by even a small amount. Photo courtesy of FHWA. Photo courtesy of FHWA Part 1 Introduction

CDOT I-70: The Project Concrete “Whitetopping” pavement design required 8” minimum asphalt for 6” concrete Full depth 9 ¼” concrete where < 8” asphalt remains after milling This is Colorado DOT's very first experience with this concept with both 3D modeling and using automated machine guidance for a mill and white top project. The pavement design required an 8 inch minimum asphalt base for the 6 inch concrete. Full depth concrete was required where less than 8 inches of asphalt remained after milling. Photo courtesy of FHWA. Photo courtesy of FHWA Part 1 Introduction

CDOT I-70: AMG Milling Robotic Total Station – 600’ intervals
Milling machine – automatically directed mill depth Contractor’s surveyor performed independent check on original and milled surface The center of the photo shows the robotic total station in front of the pickup truck. The machine itself is cut to six foot wide swaths. The milling occurred in five or six passes. The contractor was comfortable with the signal they observed from the robotic total station up to about 300 feet. Therefore, total stations were set every 600 feet so that the machine was never more than 300 feet away. The milling machine conducts the process automatically down to the mill depth that the engineer assigned for that profile. So the machine is cutting variable depths of asphalt as it goes along. Photo courtesy of FHWA. Part 1 Introduction Photo courtesy of FHWA

CDOT I-70: AMG Milling (cont’d)
Operation manually monitored Screen reports deviation from pre-set milled elevation Track height adjusted automatically to meet milled surface profile Looking at the machine in the top photo one can see the antenna on top of the machine. The gentleman underneath the umbrella on top is operating it. He is controlling the lateral movement of the machine. But the automated machine guidance is guiding the vertical. The gentleman in the white hard hat is reading that screen in the bottom photo and the screen is telling him what deviation there is from the pre set model vision. The track height adjusts automatically to meet the profile. Photos courtesy of FHWA. Part 1 Introduction Photos courtesy of FHWA

CDOT I-70: AMG Milling (cont’d)
Greatly variable milling depths The picture on the right shows variable depths and the picture on the left shows the plan for corrections. The picture shows a five inch cut over a very short distance – in some locations there was near zero depth to mill and maintain the sub structure for the future overlay. Photo and image courtesy of FHWA. Image courtesy of FHWA Part 1 Introduction Photo courtesy of FHWA

CDOT I-70: Lessons Learned
Colorado DOT Better knowledge of technology prior to plan preparation Need survey control by owner during construction More accurate initial survey – tie in boundaries Contractor There should only be one 3D model Boundaries were a problem – even in rural setting 8% allowable concrete overrun is very tight CDOT survey (pre-bid)  more competitive bids Many lessons learned came about from this project. CDOT discovered that, being their first project, they could have benefited from a better knowledge of the technology during the plan preparation process. They took the risk on this first project to recognize the potential savings and understand better the 3D modeling process and automated machine guidance. They learned that they need to have survey control by the owner during construction. The contractor noted that there should be only one 3D model used instead of the prime contractor having their own model. On this project, 8% allowable concrete overrun is very tight. Also, an owner survey is important as part of this process. Part 1 Introduction

Benefits – Quality Assurance, Cost Savings, and Schedule Savings
The next few slides cover benefits in terms of quality assurance, cost savings, and schedule savings. Part 1 Introduction

Quality Assurance Without
3D Modeling Quality assurance can be performed easily and more accurately in the 3D model world. Instead of verifying quantities with stakes, there is a more accurate and simpler process. These photos show QA using stakes and strings. Photo courtesy of FHWA Part 1 Introduction

Quality Assurance With 3D
Modeling Advance positioning technologies such as GPS, total stations and lasers can be used to find locations for construction QA/QC tests. Photo courtesy of David White, Iowa State University. Photo courtesy of David White, Iowa State University Part 1 Introduction

Data Transfer: Benefits, Procedures, and Challenges
Transferring electronic data from owner organizations to contractors is an important element in the success of a 3D modeling effort. This diagram that we have examined previously reminds us of that. Several years old, sometimes Part 1 Introduction

Preferred Import/Export Capabilities
Trans XML Autodesk Bentley Carlson Trimble Topcon Leica There are two primary highway software development companies: Autodesk and Bentley and each have their own proprietary methods for filing data. Also, there are three advanced positioning hardware manufacturers: Leica, Topcon, and Trimble, each of which provides software to prepare 3D data for conversion into their proprietary electronic file system. Carlson has developed software that performs both 3D modeling and data preparation. The Trans XML markup language was developed to provide a non-proprietary method for data transfer among all these platforms. Part 1 Introduction

Another Import/Export Scheme
Leica Trimble Topcon Autodesk Bentley Carlson Since there are only two software developers, three hardware manufacturers, and one developer that does both 3D modeling and data preparation, all of these entities have developed import and export capabilities that allow their software to transfer data directly. Therefore, Trans XML has not been as popular as originally envisioned. However, government agencies prefer having a non proprietary data exchange mechanism because the approach provides a more level playing field, especially for possible new entrants. Also, Trans XML has a very compact file size with makes it an attractive data transfer mechanism. Part 1 Introduction

Perceived AMG Benefits – Phase I Survey
Contractor Agency P/C Equipment Vendors Labor savings (direct cost on projects) 96% 76% 80% Environmental-Fuel savings N/A 36% 60% Project schedule compression 86% 57% 93% Avoidance of re-work (re-grading) 87% As-built documentation 58% Ease of constructability review 44% 49% 73% Jobsite safety 68% Safety of the traveling public 31% 40% * Percentage of respondents choosing the benefit at the two highest risk levels An important benefit of 3D modeling is that having a 3D model available encourages contractors to use automatic machine guidance (AMG) during construction. According to a survey that was conducted for NCHRP project 10-77, labor savings and schedule compression are important benefits of using AMG. This survey included over 400 respondents who participate in AMG in various ways. In this slide, we examine the responses of contractors, agency construction and procurement personnel, and construction equipment vendors (dealers and manufacturers). Source: NCHRP 10-77 Source: NCHRP 10-77 Part 1 Introduction

Productivity Impacts This slide compares the frequency of response for contractors and equipment vendors for the question of how much productivity is improved by the use of AMG. Although the vendors were more optimistic than the contractors, even the lower percentages of productivity increase acknowledged by contractors (about 25% on average) is important when one considers that a profit margin for most contractors is less than 10%. The slide also shows measured productivity increases in published case studies. The greatest increase was reported for fine grading tasks. Source: NCHRP Part 1 Introduction Source: NCHRP 10-77

Additional Resources McGraw Hill Smart Market Report – The Business Value of BIM Implementation of GPS Controlled Highway Construction Equipment (Vonderohe, University of Wisconsin) AASHTO AMG Quick Reference Guide NCHRP 10-77 Here are a few sources of literature on this topic. The participant workbook also provides a resource for information and terminology. Part 1 Introduction

Summary 3D Modeling can provide for increased efficiencies in projects by providing an intuitive user interface, identifying potential issues early on, and linking to cost effective construction methods such as AMG. Session II will focus on the application of these practices and components, along with challenges and project selection criteria. In summary, 3D modeling can provide many benefits to owners, designers, contractors, and the public. Increased application of field technologies can provide for efficiencies in constructing highway facilities including cost and time. The second part of this presentation focuses on application of 3D models and such field technologies. Part 1 Introduction

Questions? Charles Jahren, ISU Douglas Townes, FHWA Chris Schneider, FHWA Please questions to FHWA or our lead presenter using the information provided on this slide. Part 1 Introduction

3D Engineered Models for Construction

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