Know What’s Below

Expanding BIM Strategies to Buried Construction Zones

By Rachel Rogers

city-and-pipesUnanticipated structures beneath the surface of a construction site can quickly become costly and dangerous surprises. Underground utility networks for water, sanitary, storm, gas, communications and other subsurface facilities can be problematic for project teams when poor record keeping prevents construction crews from being aware of existing assets that have been added or abandoned over time. Risks resulting from unknown subsurface structures can range from project delays to damaged subsurface utilities to explosions that can threaten human lives.

Furthermore, dealing with underground infrastructure that in some cities has been in place for more than 100 years is a major challenge that directly affects project budgets. Engineers, project and utility owners, and constructors need a cost-effective solution to improve planning, constructability and operations of infrastructure projects, which helps to manage, and ultimately prevent, unexpected dangers and impediments to construction.

BIM Technology Integrates Underground Information

To “know what’s below” requires engineers to conduct site surveys and gather information on the underground utilities, such as where the piping or conduit is located, who the owner is, who made or installed it, what the attributes are, and who governs it. To gain a clear picture of the subsurface assets, it is essential that project teams have reliable access to a huge amount of data obtained from multiple sources. Project teams need modern technology to consolidate and review existing data, capture new data, and process the data to create a utility conflict matrix that can be incorporated into the project strategy and timeline.

Using a comprehensive approach that automatically creates 3D models from survey information, CAD artifacts, GIS, Excel spreadsheets, Oracle databases, and other industry-standard information sources simplifies the data integration process. By expanding traditional BIM technology to incorporate intelligent, 3D feature-based models of underground utility networks, engineers now have a reliable strategy to help mitigate risk when building in utility-congested subsurface environments.

Feature-based Modeling Facilitates Planning, Decision Making

Feature-based modeling supports the storage, retrieval, and use of 3D utility location data, enhancing information mobility for a more proactive approach to avoiding subsurface structures during construction, and for maintaining an accurate database of utilities for future projects. With innovative technology, users can easily generate high fidelity, intelligent, 3D feature-based models of buried construction zones, empowering project teams to better understand, and more effectively resolve underground infrastructure conflicts. Breakthrough technology enables immersive modeling that combines active plan, profile, and cross-section views with 3D modeling to provide additional context for real-time decision-making.

Feature-based models incorporate fully dynamic rules, relationships and constraints to improve design quality, enhance optioneering, and allow users to create and compare design alternatives. By evaluating and manipulating these computational models, project teams can integrate the underground utilities into the roadway and infrastructure designs to optimize planning and improve constructability.

Moreover, such models conform to essential elements of the Standard Guideline for the Collection and Depiction of Existing Subsurface Utility Data (ASCE Standard 38-02) UK NJUG (National Joint Utilities Group), CSA S250, AU IT-036, and other global organizations governing quality standards of subsurface utility information. As a result, engineers, project owners, and constructors have reliable information on existing underground networks in a defined manner, enabling them to develop strategies to minimize risk.

Creating 3D models from survey information, CAD artifacts, GIS, and other standard information sources simplifies the data integration process and increases the overall quality of the design project.

Creating 3D models from survey information, CAD artifacts, GIS, and other standard information sources simplifies the data integration process and increases the overall quality of the design project.

Conflict Analysis Improves Constructability

Expanding BIM technology to incorporate every element of the existing underground utility system with its exact location and elevation helps engineers and contractors avoid potential collisions. With reliable information underpinning intelligent models, users can work in a simulated environment to perform conflict analysis, cross-checking utility against utility and utilities against road or site design features, such as bridge foundations, to manage clashes that arise in congested subsurface project zones. The ability to visualize underground infrastructure as a 3D feature-based model and conduct clash detection allows project teams to determine conflicts between new construction features and existing utilities during the design phase, mitigating risk during construction, saving time, lowering costs, and enhancing overall constructability and structural integrity.

Dual Information Exchange Optimizes Data Integrity

Accurate modeling of underground utilities requires that civil and GIS information are synchronized to access, modify, analyze, and update data. Using robust modeling technology with a two-way information exchange between the design and geospatial database, users can extract as-is conditions from the spatial database to add to the 3D model, and post data to the spatial database, removing, updating, and creating new utilities based on project criteria. With automated data capture and dual information exchange, users can modify civil design features and post updates back to the GIS data source so that data is always current in the subsurface utility design. This bi-directional link to geospatial data ensures that as-built project data is exported to the database to continually grow and improve available data. The enhanced information mobility provides a reliable, consistent relationship between CAD and GIS data sources throughout the project, optimizing designs and data integrity.

Subsurface Utility Engineering (SUE) Technology in Action

Feature-based modeling enables subsurface utility engineers, project managers, and utility owners to collaborate and resolve utility conflicts in real-time during the design phase to more accurately plan the construction schedule and allocate resources, saving significant time and money.

As an example, Utility Mapping Services utilized SUE technology to identify a construction route for a new natural gas main project for Puget Sound Energy. The $4 million high-pressure, natural gas main project was planned along a stretch of a busy highway in Lacey, Washington. The project corridor included complex, existing utility infrastructure woven through dense commercial and residential areas, which had limited right-of-way and substantial traffic flow.

To manage this challenge, Utility Mapping Services used GEOPAK, Bentley’s SUE technology to create a 3D model and a virtual reality rendering of the existing utility infrastructure along the corridor. Resolving conflicts during the design phase allowed the contractor to accurately plan the construction schedule and allocate the appropriate resources. The model enabled engineers to value engineer design alternatives and obtain required variances which shortened construction time and lowered construction bids.

Ultimately, the technology enabled the team to identify the best route for the new gas main, which minimized the impact of the construction on the local community, helped the construction team to avoid existing structures, and reduced project delivery time and costs.

Intelligent 3D models incorporate fully dynamic rules, relationships and constraints to improve design quality, enhance optioneering and allow users to readily create and compare design alternatives.

Intelligent 3D models incorporate fully dynamic rules, relationships and constraints to improve design quality, enhance optioneering and allow users to readily create and compare design alternatives.

Trending in Subsurface Utility Engineering

Due to the growing trend of using BIM strategies to build underground 3D integrated projects, virtual reality tools with augmented reality capabilities are also becoming more prevalent in infrastructure design. Because engineers are becoming more engaged with optioneering and using real-time data to support and validate design options, collaborative 3D modeling has become integral to design and construction and feature-based modeling is essential for subsurface utilities and drainage systems.

Working in an integrated 3D modeling environment facilitates collaboration among engineering organizations, utility owners, and agencies for better lifecycle management of underground utilities. New subsurface utility engineering technology provides a framework of tools for building intelligent 3D feature-based models of the buried construction zone that can be integrated into roadway and other infrastructure designs to ensure drainage and mitigate risk building in utility-congested underground areas.

As buried utilities continue to pose significant risks to projects and globally, there is an imminent need for continued advancement in information modeling and mobility to improve constructability and enhance the safety, reliability, and resilience of infrastructure assets. With proven 3D workflows that have dual structured pathways to and from the spatial repository, innovative modeling software is now available to users to take underground modeling to the next level.

Rachel Rogers is the application marketing director for Bentley’s civil design, geospatial, imaging and hydraulic and hydrology products.

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