Designing with BIM for Infrastructure on Large Transportation Projects

Transcription

1 Designing with BIM for Infrastructure on Large Transportation Projects July 19, 2012, 10:00 a.m. Pacific Time Join civil designer Dave DeJong from Stantec as he discusses how BIM for Infrastructure has allowed his team to tackle large roadway projects and new delivery methods. View the archived webcast at Learning Objectives Learn about Stantec s project planning process for design workflow development See examples of data organization and design workflows for large transportation projects Discover how Stantec uses BIM for Infrastructure to support alternative delivery methods, such as machine control grading Understand strategies for creating models to suit deliverable construction requirements About the Authors Dave dejong is a CAD manager and civil designer for Stantec in Kamloops and Vancouver, B.C., Canada. His experience includes survey, design, visualization, and management of infrastructure, subdivisions, roads, and highways. He has been in the consulting industry for 16 years, and also does AutoCAD Civil 3D training for Stantec. He was selected as an Ipanema Gunslinger in 2011, and has been using Civil 3D in production since dave.dejong@stantec.com David Kasha is currently one of several practice technology coordinators at Stantec Consulting.. David s role is to provide training and support on AutoCAD Civil 3D, coordinate and evolve corporate CAD standards, and help institute corporate document management practices with acquired firms. Prior to joining Stantec in 2001, David ran his own CAD consulting business for eight years and was a Autodesk Authorized Independent AEC Consultant. During that time, he assisted different firms and government organizations with the training and implementation of Autodesk Land Desktop, and provided assistance to consulting firms on highway and site design projects. He also worked on contract with Softdesk/Autodesk to produce tutorials, conduct user workshops, make sales presentations, provide dealer training, and test beta software. david.kasha@stantec.com

2 Project Preparation True 3D model based design The selling points to using true model based design (BIM for Infrastructure) are: Modeling allows you to examine alternative design options more quickly The impact of those options can be easier to spot in other aspects of the design (utilities, line of site/aesthetics, etc). Facilitates better sharing of design information between disciplines because changes to the model become visible to others even if the additional step of notifying team members of the change is missed. Efficiency of revisions - Once the documentation of the design (the drawings for the plotted sheets) is setup, changes in the design are automatically reflected in the documentation. Aspects of the drafting/documentation can be setup while the design is still occurring. Easier to communicate the design intent to non-technical stake holders Adjusting to a different design process Undertaking the 3D model-based design process affects everyone on the project, from the cad users to document control to project management. Designers build the model, not drafters Submitting model-based drawings is different from traditionally-produced drawings Archiving of data is an important consideration Getting Help Checking Egos at the Door Training is required for employees Asking the right questions to shape success How big is the project, Where is the project, Who are the team members, Where are the team members and how the heck will you communicate? Standard engineering practice for big jobs dictates proper document management control but how does this dynamic 3D model fit into that control structure? 2

3 Deliverables dictate the model Understanding the deliverables will determine the complexity of the model and how it needs to be structured. Example deliverables include: sealed paper/pdf drawings and 3D model (surfaces, alignments, profiles). Quantities The quantities are critical to success. Quantities may be submitted at various points throughout the design of each roadway segment. Data Sharing The current Civil 3D data would need to be shared between all design groups. Standards Development The standard has to help keep the model clean (no special little files or sketches that s death to a C3D project) The CAD Manual A project-specific CAD Manual was created to help keep the team consistent in their production. It is critical for proper communication. The last version was 49 pages. Directory Structure / Mapped Drive A standard directory structure was created for all design groups. A standard mapped drive letter was also assigned this way the standard directory structure could be located in various places between consultants, disciplines, offices, etc., and maintain the same pathing. File Naming A system was created that allowed no confusion or redundancy. A key element in the file name is a discipline code (2-digit number). This made it clear who owned the files as they were being shared. The rule became: don t modify any files that don t have your discipline code. The Drawing Template A DWT was created for the project, and was based on the available BC MOT 2010 CAD standards. These standards did not include any Civil 3D styles, but did have NCS compliant layer names. Fields in title block were used with Sheet Set Manager. 3

4 Civil 3D objects and Styles Naming Conventions As an example, understanding which alignment is to be used as a target with the various sub-assemblies is critical to successfully building the corridor model. With the vast amount of Civil 3D data being shared via data shortcuts it is imperative that a naming convention be developed for all civil 3D objects such as alignments, profiles, surfaces and feature lines. Style naming convention provides a common language that can be used to identify which group created the style and what the style shows. Civil 3D data Architecture Brainstorming This was a very important step in the process. A day was spent in a room with some of the primary CAD designers examining deliverables, project requirements, hardware performance constraints, dynamic modeling requirement. Questions to Ask The following questions asked at the onset of a project will be invaluable in designing the data architecture: Who will be working on it? How many people? Where will they be working on it? Which offices? Which type of information does each discipline need from the other? What are the deliverables? How much detail do we put into the model? Are all deliverables required at every submission? Is the contractor going to use machine controlled equipment? Will we supply the model or data exported from the model? When do you need this by? Be specific when do you need quantities? Layout data? 4

5 Data Structure There is a differentiation between model files and sheet files. Autodesk CE News Webcasts The illustration on the next page shows our data architecture based on the brain storming session, then refined through experience, as it relates to the model files. Key points: Data broken up to maintain good performance The model is built per segment (example project has 8 segments) The composite corridor surface drawings were created to simplify sharing of the model with utility designers and landscape architects. Both the top and datum surfaces get consolidated from the various corridor drawings in the segment. The corridor drawings were x-referenced into the section drawings because an x- reference of a corridor will show up as data that can be sampled in a sample line group. Section sheets were a blend between a Model file and a Sheet file because of the sample line groups. Unlike other drawings where each one represented a plotted sheet, multiple PS layout tabs were used for the cross section sheets. 5

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7 This illustration shows our data architecture as it relates to the sheet files. 7

8 Civil 3D Data Shortcuts Data shortcuts were used extensively to reference data between the model and sheet files. This method is good, but had its challenges. Originally, we thought that some design groups, such as utilities and drainage, would have a copy of the whole model. They would make use of the data shortcuts created by the roads group, plus create their own from the composite surfaces. It ended up being simpler for those design groups to just make shortcuts from the promoted surface files they needed. Some issues encountered were: A bug was discovered that allowed conflicting shortcut XML files to be created, depending on which drawing was used to originally create the shortcut this was corrected by Autodesk. If referenced objects or their source files get renamed, the shortcut gets broken. Unused or superseded data needs to be cleaned out, or the data shortcuts will get messy. Since we used a common mapped drive letter, drawings should be opened through that drive. This was critical for the creation of data shortcuts, as this source path gets saved in the shortcut XML file. Xrefs Xrefs were utilized for base information, plus for some model information. All xrefs were to be overlaid and use relative paths. The use of Overlay helps avoid issues with circular references and ensures that only the information that is expected/wanted is brought in. The relative paths facilitated sharing of the files between design groups, and is also helpful in data archiving. Promoted Data Composite surfaces needed to be saved two ways. First was the dynamic model file. Second was a promoted version of that file. The promoted version allowed other users of the data to reference the surface without needing a copy of the entire model (with corridors and data shortcuts). Promoted versions were re-saved weekly as the files were shared with the team, plus for all submissions. 8

9 Developing Best Practices to help performance & ease of use Besides the drawing architecture being developed to prevent drawings from getting too big and slow, there are best practices that can help simplify the model and increase efficiency: Create one corridor drawing per alignment. You can also include multiple, short secondary roads in one corridor drawing. We modeled 4-5km (2.5-3mi) of main line in one corridor the file size ranged from 5-20mb, depending on level of detail & complexity. Turn off regions not in use. Doing this when you are working on a particular area will speed up rebuild and regeneration times. Don t turn off all the regions! This will remove the corridor surface data, which can ripple down through the data shortcuts and create errors for other users. When you re done editing, make sure to save the drawing with all corridors turned on remember that the resulting surface is being used by others. Conditional sub-assemblies reduce the number of assemblies required and the number of regions. They can also make for smoother corridor surfaces with less errors. Different, streamlined code set styles were developed for various uses. The one for assemblies showed the shape and point codes. The one for corridor design was slimmed down to not show all the point codes and links this increased corridor performance. Design Stage Once the model is built, revisions to the design become easier. Delivering on the promise of Dynamic 3D modeling Civil 3D allowed us to develop design alternatives and communicate those designs well. We participated in value-engineering exercises, using a live 3D model. We explored alternatives, being able to see cross sections and volume calculations for each one. Revisions to the alternatives could be made on the fly, and the whole team had up-to-date sections to evaluate. This ability allows the consultant to develop a better design in the time same amount of time. The 3D model allowed the team to work across different offices and disciplines, with information that was never more than a week out of date. We did not have issues with other disciplines advancing a design based on old information. 9

10 Maintaining the dynamic relationship all the way through to the sheet files had numerous advantages: It saved hours of manual changes to drawings when revisions occurred It ensured the latest design information was being shown on the sheets It eliminated discrepancies between the printed sheets in the field, and the 3D layout info It was impressive that the corridor model for the sample project was created with the standard sub-assemblies that ship with the software. No customization was required only creativity. Managing issues There is a different workflow required for a 3D model based design. This is important for project management to understand because there is more upfront effort to produce the sheets. 80% of the final drafting is done with the first iteration of the design. As design changes come the revisions can be accommodated with less effort as the labels update themselves. Bad data in still equals bad data out. Designers understand alignments, profiles and cross sections, but there is still a poor understanding of what a TIN is. Understanding the TIN is now even more important because surfaces are deliverables. There was initially some bad TIN modeling by team members, which also did not get picked up during the initial QC. Another layer of QC was required specifically for surfaces, and Civil 3D s ability to analyze surfaces quickly via styles showing slopes, elevations, contours, tin and points was invaluable during this process. We are able to narrow down surface errors using one or a combination of these styles. A clean model makes life easier and everything downstream works better. People will still do things the way they re most comfortable with this was a source of some performance issues on the project. Over-modeling is another concern and is inefficient. Weekly CAD meeting where held to discuss modeling and drafting issues and educate the team on best practices. It is key to recognize that we originally built the model architecture, and then continued to revise those same model files throughout the duration of the project. Design alternatives or options need to be developed in secondary files. 10

11 Adjustment made mid-stream Can you plan for making changes mid-stream? What prep can be made for this. Data Sharing Ultimately Buzzsaw File sharing performance with a 3rd party collaboration site was not ideal for this project. Buzzsaw allowed us to reproduce our standard folder structure, and control access based on disciplines. How changes are communicated to Design team Changes to the design are updated weekly on Buzzsaw and everyone knew this. Other forms of communication were still required to convey the details of design changes to other team members. Software performance with large data sets required architecture adjustment Some corridor files became more complex than others, and performance do lag. To resolve these, the corridor drawing can be split into two. Drawing production Many kilometers of main line road, secondary roads, separate drainage and utility drawings, electrical, signage, structural, landscaping, geotechnical and environmental makes for a lot of drawings. Drawing production tools make sheet creation quicker. Sheet set manager saves time when issuing drawings, changing revisions, etc., and publishing drawings to paper or PDF. Once a plan Sheet Set had been developed for roads, other disciplines such as Landscape can use it as the basis of their sheet production. Construction Besides the use of sealed paper drawings as the legal means to communicate the design intent, 3D digital information is often provided to the client. Layout/ Machine controlled grading In an ideal world the consultant would provide the design to the contractor in the form of the finished 3D model of the site and the contractor would use that model to create the layout points and the information required for machine controlled grading. In reality how do you provide this very complex 3D model system to someone who has not been involved with its creation and have them understand how to work with it and get the data they need out of it, with zero chance of error?. It would require a very well documented process 11

12 explaining what was in these deliverable model files and a high level of familiarity with the technology to properly receive and process the files. One idea would be for the consultant to provide layout files to the contractor. This also provides another means of QC for the final model. Some contractors we work with use Trimble equipment. Trimble Link can be used to export surfaces to TTM (trimble terrain model) format. Surfaces can also be exported to XML for use by subcontractors with other equipment. Alignments and profiles can be exported to XML. In addition to a surface, breaklines identifying grade changes (i.e. topo of banks, toe of slopes, crowns) can be created so the machine operator would have precise background information to view in the field. Another aspect of having the consultant generate the layout files is to deal with the complexity of managing the revisions to the model during a design/build. As a design change is made and approved, but other design changes are still being made to other aspects of the model, providing layout files for an area helps limit any confusion as to what was being issued for construction. 12

13 Post Mortem Lessons Learned At the end of each project, the design team needs to ask: What would we do differently? What was done well? Here are some examples from our recent projects: One of the successes was how every design group always had access to the latest digital design information. We escaped the inefficiencies of advancing a design using old information. The project CAD Manual was important to convey the model architecture to the team, plus other information like model file naming. Some way of ensuring adherence to modeling procedures would be very useful. Testing of the data architecture with a more complex example before the beginning of the job would have been better. However, there s not always time for that on a P3 design/build. Cleanliness is next to Godliness! Having a consistent, standard level of detail in modeling is important and could have been improved. A standard assembly was built at the beginning and all road designers used the same basic subassemblies this is required for consistent coding throughout the project (points/feature lines, links and shapes). Coding for machine control purposes (gravel surface creation) was incorporated into the model later on. Determining the details of every deliverable on a 3D project is not always feasible at the very beginning, especially when it s a learning process for everyone involved. The entire design team needs to know the bigger picture. Taking a shortcut may get the immediate job done, but causes issues downstream. It s important to follow the plan. Don t create sketches or exhibits in the model files these may be your files, but they are shared with everyone. Be patient and thorough. Download all the data so as not to leave out info coming from the shortcuts. The intermediate step of creating a drawing that contained a composite/combined surface that then gets promoted is an important step to eliminate issues when passing the data to other disciplines. It makes things simple. K.I.S.S. is good. Make sure the designers really understand what they are doing with a TIN, what they are looking at, and how they verify the surface has been built properly. The basics are still important. COMMUNICATION especially between disciplines. 13