In delivering the complex East Link Extension for Sound Transit in Bellevue, Wash., some of the teams harnessed the power of building information modeling (BIM) — and some did not.
Contractors for two of the six stations on the east side of Lake Washington chose to incorporate a digital model in their work. Their results show the power of using 3D models on major projects.
Construction on the stations that used BIM were more efficient, resolving clashes in weeks rather than months well ahead of construction. The stations and contractors that went the traditional design plan route submitted high volumes of requests for information. The process to resolve simple items took more time: comment, response, follow-up question, and response. In fact, one station team that didn’t initially use BIM ended up creating a BIM model for clash detection purposes, expediting the work.
The East Link Extension shows how even limited use of digital modeling can solve complex, sticky issues during construction. Other projects — including Los Angeles World Airport’s Automated People Mover and Metrolinx’s Ontario Line in Toronto — have embraced the benefits of 3D modeling from the start and unleashed the power of digital delivery to improve efficiencies and collaboration throughout the project lifecycle.
These case studies show how incorporating 3D modeling can create efficiencies during construction of transit projects, whether that modeling is used in the design of smaller parts or throughout the planning and delivery of the project.
Benefits of 3D Modeling and BIM: Reduced Change Orders & Schedule Delays
Building information modeling has been used in vertical architecture for decades, benefitting the design and construction of buildings. Of late, its use has become more commonplace in the horizontal civil construction world, offering improvements in the design and construction of highways, roads, and bridges. Adoption of digital delivery for transit projects is increasing as agencies uncover a host of benefits from using BIM at both project and program levels.
A new study from the Federal Highway Administration’s Turner-Fairbank Highway Research Center, through the Transportation Research Board, recently quantified the costs and benefits of digital delivery. The study, prepared by HDR, found that throughout an agency, a move toward digital delivery typically pays for itself within a few years. The research found that agencies can benefit from the use of BIM for major projects, but also for smaller or routine projects as well.
- Direct cost savings due to the use of BIM, including avoided change orders, improved schedule management and optimization of design. In fact, the reduced change orders alone can save about 15% of project costs — a major benefit especially for multi-billion-dollar programs with complex construction needs.
- Staff time savings – efficiency gains, saving time on a particular task.
- User benefits – realized by the public.
East Link Project Shows the Power of 3D Modeling to Accelerate Problem Solving
In the Sound Transit case, the digital model improved clash detection, identifying spatial interferences where the piping, conduits, and other discipline assets might intersect.
This facilitated collaborative problem-solving between the owner, construction manager, and contractors. The number of requests for information from the contractor team decreased. More importantly, the team was able to work in real time to identify solutions, reducing the multiple rounds of question, response, follow-up question, and response that typically happens when working through solutions without all the information so readily visible.
With a digital model, the team could visualize the conduits, equipment, HVAC lines, and other items that needed to fit into the stations and find a proper routing for everything. The use of BIM enabled the team to see, in 3D, the conflicts that needed to be addressed and how moving one element impacted or affected other elements in the station. In construction, time is everything, and delays quickly add up to significant costs that can impact the contractor and, potentially, the owner. Running a clash detection program immediately showed the design team a potential flaw in a plan, allowing them to pivot.
Los Angeles World Airports Automated People Mover Design-Build
At Los Angeles International Airport (LAX), a new 2.25-mile automated people mover is being constructed in the middle of the fifth-busiest airport in the world. One particularly complex area was the project’s maintenance and storage facility, which includes communication rooms that monitor and control the automated train system. These elements must fit alongside the HVAC systems, elevator/escalator systems, and fire detection systems that are standard in any building today.
These same systems must be transmitted across the guideway to allow for monitoring and control of the trains and equipment from the central control center. BIM allowed the designers to fine tune all the interfacing details in the design phase where it had the least cost and impact. Continuing the use of BIM during the construction phase allowed real-time resolution of potential issues as they arose with minimal impact to construction schedules.
This project became one of the largest building information modeling projects in the U.S., with more than 150 design models, created and maintained by more than 300 BIM designers. The collection of these models, known as the “federated” model, was utilized for a variety of use cases, including 3D clash detection, enhanced visualization, and even for 4D construction phasing, detailing specifics of construction of the elevated guideway through critical project interfaces within the highly congested Central Terminal Area at LAX.
BIM was a part of the plan from the outset, and the designer and contractor wrote the BIM execution plan together to ensure a smooth handoff and effective utilization of models throughout the project's lifecycle. This allowed for effective handoff of models from design to construction.
As the contractor moved through construction, design models were coordinated with construction trade contractors, allowing issues to be found in office rather than in the field. At the end of the project, LAWA will be able to utilize these models for digital as-builts. Rather than providing countless paper plans for asset management, there is one central model. This will have tremendous benefits for ongoing maintenance of the system and particularly future projects.
Metrolinx’s Ontario Line Team Embraces Digital Delivery from the Start
Another agency that’s pushing boundaries with digital modeling is Metrolinx. Complementing its vision of a new Ontario Line subway in downtown Toronto, the agency is bringing together BIM, GIS, data acquisition, and many more digital tools to create a streamlined, efficient information sharing process across a massive international team.
In 2020, the team started with a core agreement to think in 3D. From there, opportunities to enhance use of 3D models grew organically as the team incorporated and utilized additional existing tools into their workflows. For example, 4D modeling allows the team to address constructability during the design phase. Using lidar and reality mesh produced visuals to show the design for the approximate 9.7-mile subway line and enhance the understanding of how it is integrated into the existing environment. As each designer creates an individual 3D model, it is pulled into a weekly federated digital model, compiling information from multiple teams across international time zones into one source of truth representing that week's status and progress with design progression.
Through BIM and GIS integration, the 2D, 3D, and reality capture data generated for the program are brought together through a web-based GIS viewer. This enables an enhanced understanding for project managers, the client, and others not traditionally familiar with BIM tools, allowing all parties to stay up to speed with the latest information through a simple web interface.
At the end of this project, like LAWA’s automated people-mover, Metrolinx will have an as-built digital model of the Ontario Line to inform future projects and assist with ongoing asset management of the system.
Uses of 3D Modeling in Transit
Transit projects and programs are ripe for the use of BIM.
Building a new transit station or line can include new bridges, new utilities, changes to the roadway, new buildings, and more. It requires coordination across many disciplines and between the designer and contractor.
In addition to design clarification and clash detection, virtual tools also support public outreach efforts for transit agencies. For Sound Transit on the East Link Extension project, BIM and other virtual tools were used to communicate complicated sequencing and construction activities to the public. These tools provided an easy-to-understand visual representation for community members, so that they could better understand temporary impacts to pedestrian, bicycle, and vehicular traffic mobility.
As a new wave of projects enter the early design stage, Sound Transit will be using virtual tools to support planning and messaging around the development of alignment alternatives. Virtual representations of complicated design solutions have become a valuable tool for the agency’s efforts to communicate future development.
Another benefit of using BIM, or other digital tools, is the scalability — it is not all or nothing. Digital delivery can be a customized, tailored approach, and agencies can take it one step at a time, such as starting with 3D modeling for enhanced design review. As agency staff grow familiar with and confident in the use of digital modeling, the agency can expand and increase the benefits through added BIM use cases across the project lifecycle, from preliminary design to asset management.
Getting Started with Digital Delivery
Early adoption and implementation can be tailored to an agency’s needs — either from the start of a complex project or to solve a specific problem during design or accelerated project delivery. Either scenario benefits the agency and the industry in advancing the use of digital delivery to reduce risks, enhance delivery performance, and improve outcomes for everyone.
Often the biggest obstacle is comfort level. Using BIM requires adopting a new way of thinking, and it can be intimidating. But those of us who have used it have found that, with the right training and cross-team collaboration, digital delivery leads us to be more productive, more connected, and more informed to address delivery challenges and potential conflicts.
The use of BIM in the construction phase has fundamentally changed the efficiency of the work and streamlines the process for getting much needed actionable answers to the contractor.
Transit agencies with an eye toward the future can follow the lead of vertical architecture and embrace the efficiencies and benefits — improved risk mitigation, time, and cost savings — that come with digital delivery.
Mike Bell, DBIA, is the Sr. Executive Project Director at Sound Transit responsible for delivering the East Link Extension; Justin Garrod, PMP, CCM, is HDR’s northwest transit lead and led HDR’s construction management work on Sound Transit’s East Link Extension project; and Cameron Schaefer, PE, serves as the transportation data acquisition/reality mesh director for HDR.
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