BIM keeps complex rail project on track

by: Teresa Elliott | 09/29/2015
Estimated Reading time: 9 - 14 minutes

Project: MTR Shatin to Central Link (SCL) Construction Scoping and Sequencing Project

MTR and Arup

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Arup wins 1st place in the Autodesk 2015 Excellence in Infrastructure for MTR Shatin to Central Link (SCL) construction scoping and sequencing project. This is the city view of the Wan Chai upon completion of the SCL and Exhibition Station. Image courtesy of Arup and MTR.

Arup was awarded the first place prize in the Autodesk-sponsored 2015 Excellence in Infrastructure competition for its consultancy work in MTR Shatin to Central Link. This project is a 17 km railway line expansion undertaken by MTR in Kowloon and Hong Kong Island. The project involves construction of 1.8 km twin railway tunnels, a new underground station with interchange facilities, as well as ventilation buildings and shafts in Wan Chai on Hong Kong Island—one of the most built-up and busiest commercial areas in the territory.

Coordination and communication: keys to success 

The geographical diversity, project complexity, and public nature of civil work results in an exceptionally challenging industry that demands a high level of technical expertise and requires constant coordination and communication. Whether building on land or over water, in urban centers or across, under, or through multiple terrains, the more complex the project the greater the need to improve coordination and collaboration. I can’t think of a better project to highlight the need for a very intentional coordinated effort than the MTR Shatin to Central Link (SCL) Construction Scoping and Sequencing Project in Hong Kong. Sure, there have been many high-profile projects where there was a lot of talk about the close coordination between owner and engineering and construction stakeholders. But this project has a bit of everything—buildings being built, buildings being demolished, changes to structures for a new station, consideration for tying into existing or future lines/stations, as well as other facilities/utilities considerations.

Exhibition Station will be located underneath an existing public transport interchange and sports complex. And as the interchange station between SCL and the future North Island Line, the station will house a number of building services and system installations to support railway operations—tunnel ventilation systems, traction power systems, and operation and signaling systems. All of these installations will require structural and architectural provisions to accommodate them. And, there are several surrounding facilities that are affected—these are the extended stakeholders adjoining the station, including the police officers club, Harbour Road Sports Centre, and Wan Chai Swimming Pool.

Close coordination

Coordination from the onset is critical because of the large number of stakeholders, facilities, buildings, etc. Making good decisions early about designs and areas where there might be conflicts between the various stakeholders can help minimize potentially costly rework later in the project. Coordination with the public has to be almost nonstop. I’m sure you could quickly name some complex projects where the public is very engaged in discussions about what will happen, what will change, when will it change, and how neighborhoods, streets, etc., will be affected. How long will the construction go on? Will it hurt property values? What is the risk to safety? And so on.

What makes this project interesting to me is this wrinkle: In addition to all of the above stakeholders, there is an extended stakeholder group that includes surrounding building owners (private and public) and the associated business owners that will be affected by the project. So, not only will this group care about the same issues as the general public, but also they’ll have other concerns—for example:

  • Facilities that need to be changed as a result of the construction (utilities or other assets by a separate building owner could be obstructing the new development)Older buildings that must be modified/encroached upon for the building of the new facility (a swimming pool)
  • Traffic closures or diverting traffic—both could affect those businesses for an extended time period. They will want to understand the timelines because this can affect their operating hours and ultimately their revenue.
  • Construction that would require downtime of their business for safety reasons
  • Other safety issues, like the location of construction equipment

And yet, with this project there is another wrinkle: This project must tie into other stations and lines, a factor that must be considered during design and construction, making it increasingly complex to make design decisions and highly critical to collaborate very early in order to minimize design and construction issues.

Existing conditions help improve decision-making

Early engagement with stakeholders proved to be very beneficial. In several reprovisioned public facilities (including the Harbour Road Sports Centre and Wan Chai Swimming Pool), the BIM model was introduced to the electrical and mechanical services department—the ultimate facilities maintainer—to obtain their comments and early consent of approval. Since space provision and maintainability can be clearly assured using the BIM approach, this significantly sped up the approval process, something that would not have been possible with a traditional 2D drawing–based approach.

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The image shows the sectioning of the new underground Exhibition Station, which will house building services and system installations to support the railway operations, requiring structural and architectural provisions to accommodate them. BIM has facilitated multidisciplinary design and coordination. Image courtesy of Arup and MTR.

Also, the team carried out a detailed survey on the adjacent underground utilities and imported that information to the model. Some of these utilities directly conflict with the new station and require permanent diversion, while others cannot be diverted easily—such as the sensitive high-voltage power cables and the rigid cooling mains. Locating these utilities and loading their data into the model enables better construction sequence and diversion works planning. It also helps the team to locate cables and make necessary adjustments on the station roof structure to avoid diversion of sensitive and rigid utilities. Not only has it saved diversion costs, it has also minimized program risks on utilities diversions and reduced the impact on adjacent users and developments, as more permanent suspension of the utilities will be required.

Also, they team counter-checked the information provided by other parties, such as survey records from subcontractors. Survey information can be imported to the BIM model and converted into 3D visualization, which proves to be very useful in verifying the utilities’ vertical profiles to ensure the feasibility of the designs—ultimately helping to improve accuracy, clarity, and quality.

Integrated design helps reduce abortive work

BIM enables the designer to plan more accurately, with multiple stakeholders’ information imported to the model. The station diaphram wall design, for example, benefits greatly from the BIM model. Part of Exhibition Station will encroach into the land lot of the existing Harbour Road Sports Centre and Wan Chai Swimming Pool, and these community facilities will need to be demolished to make room for the construction of the new station. However, the existing sports complex foundations impose great constraints on the construction of the perimeter diaphragm wall, as they overlap with the wall alignment station. A typical way to solve this problem is to remove all foundation structures before excavation of the diaphragm wall. But, with the help of the BIM model, designers could more accurately locate the existing piles and foundations, and place the diaphram wall alignment so that it avoids the existing foundation as much as possible; in other words, they reduced the number of piles and foundation to be removed. This significantly minimizes the generation of construction and demolition waste due to extra pile removal work, saving time and cost for the construction team.

The BIM model informs early decision making, helps the design consultant identify and resolve problems and difficulties in geotechnics, structure, or MEP, etc., during the design stage; facilitates reduction in waste; and improves constructability planning. This will help the project to save significant time in the construction stage, and reduce abortive work, which often result in unforeseen problems and conflicts. The associated labor cost in the construction stage is expected to be substantially reduced compared with using a traditional approach.

Considerations for adjacent projects

Along the alignment of the railway tunnel and the work sites in Wan Chai North, another major infrastructure project—Central–Wanchai Bypass (CWB)—is currently in progress. Since some of the work sites overlap, the SCL team needed to coordinate the complex interface with the CWB construction team. For each design element, CWB construction works impact and constrain the SCL design, which significantly impacts the construction. These impacts vary, from program implications due to land possessions to more detailed structural loading variations on the common foundations.

The BIM model helps integrate information from adjacent projects and enables the SCL team to analyze the impacts on their project’s design. Subsequent updates can be easily imported, improving understanding of the potential impacts. The team can make necessary design changes accordingly, or return comments in case of major conflicts. BIM certainly helps speed up the checking process to further improve project performance and delivery.

Simulation is key for communications

The new station is in an area where roads are heavily congested, especially where it connects to the Cross-Harbor Tunnel—so the project required carefully coordinated site logistics. The project team had to explore construction options that would minimize the impact to adjacent road traffic.

Due to spatial constraints in the surrounding area, the construction of Exhibition Station has to be carried out in stages, with various temporary traffic management schemes. Fortunately, the design team can visualize the entire sequence using BIM-enabled project timeline simulations, greatly improving their understanding of the relationship between construction work and nearby road traffic. They can also verify constructability, identify temporal clashes, and foresee potential risks at an early design stage.

Being able to visually tell the story of the project, including construction sequencing and what to expect once the project is complete, is very useful for communication with the client and all the various stakeholder groups—from government departments and approval bodies, the district council, and adjacent building owners and tenants to the users of the affected facilities (police officers’ club), as well as the general public.

Visualization and simulation helped the team to promote a better relationship with the public. They used visualizations to more effectively communicate possible impacts during construction stages, as well as the final visual impact of the station entrance structures and the adjacent landscape and developments. And the animated sequences helped stakeholders visualize the relationship between construction of the reprovisioned sports complex, demolition of existing public facilities, and construction of the new station. It is not unusual for public complaints to arise when there is little understanding about a large complex infrastructure project or there isn’t enough transparency of the project and its potential impacts.

“As one of the first movers, Arup is committed to be at the forefront of BIM development, driving BIM use to improve its positive impact across a diverse spectrum of disciplines and projects,” said Timothy Suen, Arup fellow and director of railway in East Asia. “Using BIM in the design process is invaluable. With most works being underground and many things happening around the site, unforeseen conditions and changes are unavoidable. BIM enables us to make critical decisions using data that can be easily visualized, so the team can find alternatives more effectively with a clear overview of the sequence of work for this highly complex project.”

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Exhibition Station Concourse showing entry gates, customer service center, shops and access. Image courtesy of Arup and MTR.

 

 

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