Successful story for innovative "Full-Span Bridge Deck Erection Method" at the development of the Loop
By the Civil Engineering and Development Department
The Hetao Shenzhen-Hong Kong Science and Technology Innovation Co-operation Zone (河套深港科技創新合作區), consisting of the Shenzhen Park (深圳園區) of about 300 hectares and the Hong Kong Park (香港園區) of about 87 hectares, is one of the major cooperation platforms among Guangdong, Hong Kong and Macao under the National 14th Five-Year Plan (「十四五」規劃).
The Civil Engineering and Development Department (CEDD) plays a pivotal role in delivering the necessary infrastructure to support the vital Hong Kong Park (also known as the Loop), Figure 1, under the “Development of the Loop” project. The first package of this project, with an estimated cost of HKD$14 billion, involves extensive site formation, roadworks, and infrastructure facilities essential for establishing the Loop as a landmark hub for innovation and technology in the Greater Bay Area.
Figure 1: Artistic impression of the Hong Kong-Shenzhen Innovation and Technology Park
Engineering construction with innovation
Under the Loop project, one of the key challenges is to build a new bridge, namely the Bridge ST01, spanning over the heavily trafficked Fanling Highway and Castle Peak Road (Chau Tau Section) that encompass a total of 10 lanes. The Bridge ST01 is a single-lane carriageway of approximately 340 meters in length which connects the Loop to the Fanling Highway/San Tin Highway. It comprises 10 spans with span lengths varying between 25 meters and 44 meters. The bridge configuration is shown in Figure 2 below.
Figure 2: Overview of Bridge ST01
To overcome the constraints of limited construction timeslots for overnight work over the busy highways, CEDD has implemented a novel “Full-Span Bridge Deck Erection Method” using self-propelled modular transporters (SPMTs) for the construction of 5 out of 10 spans–a new and innovative vehicular bridge construction method in Hong Kong. This method allows for the erection of the entire bridge deck for each span in a single day, enabling faster construction and minimising public disruption, with significantly fewer road closures required. Three bridge spans have been successfully erected in 2024, as shown in Figure 3 below.
Full-Span Bridge Deck Erection Method allows for the erection of the entire bridge deck for each span in a single day, enabling faster construction and minimising public disruption, with significantly fewer road closures required.
Figure 3: Innovative “Full-Span Bridge Deck Erection Method”
Methodology and works sequence
Unlike the conventional balanced cantilever method, this innovative approach allows precast deck segments to be assembled on the ground during the day, reducing the risks associated with working at heights and nighttime operations, thereby enhancing site safety. The project team utilised SPMTs, synchronised by a wireless control system, to transport the bridge deck to the erection position. The deck was then lifted to its final position using a strand-jack lifting system and then supported by lifting frames and temporary beams. The methodology and works sequence of this innovative method involving the deployment of SPMTs and strand-jack lifting system are shown in Figure 4 below.
Figure 4: Methodology and work sequence of “Full-Span Bridge Deck Erection Method”
Features of SPMTs and Strand-Jack Lifting System
Figure 5: Feature of SPMTs and Strand-jack Lifting System
The SPMTs, equipped with a wireless control system, enabled synchronised movement for precise maneuvering of the entire bridge deck in multiple directions, allowing navigation through complex site environments, including varying ground gradients and tight spaces. The strand-jack lifting system, utilising six 220-ton strand jacks, provided efficient and precise installation of the bridge deck, Figure 5. This deployment reduced risks associated with lifting and assembling precast deck segments at height, enhancing both site safety and construction efficiency.
Benefits of the method
Compared to the traditional balanced cantilever method, this innovative construction approach aligns with the “Construction 2.0” initiative promulgated by the Development Bureau of the HKSAR Government, providing several benefits listed in Figure 6 below.
a) Social Benefit: Reduced 90% of nighttime road closures on Fanling Highway and Castle Peak Road (Chau Tau Section), minimising impacts on the local community and road users;
b) Safety Enhancement: Eliminated 80% of work-at-height activities, as the full-span bridge deck could be assembled on the ground during the day;
c) Sustainability Benefit: Reduced carbon emission by 30% through the use of fewer construction plant and equipment and significantly reduce the lighting, signing and guarding for temporary traffic arrangement; and
d) Programme Benefit: Saved 25% of time in deck construction, equivalent to about three months.
Figure 6: Benefit for the adoption of “Full-Span Bridge Deck Erection Method”
Digitalisation Design
Digital design was adopted to optimise temporary works and site operations through various technologies, including Light Detection and Ranging (LiDAR) 3D scanning and drone-based photogrammetry for precise site mapping and risk identification; comprehensive BIM modelling for engineering analysis; and augmented reality for visualising transportation and lifting operations. These technologies helped streamline construction activities and avoid abortive works.
Drone-based photogrammetry, LiDAR 3D scanning and BIM model
Recognising the challenges of maneuvering a large full-span bridge deck in a constrained area adjacent to a major highway, we created highly accurate digital data to visualise existing site conditions. Drone-based photogrammetry, equipped with high-resolution cameras, systematically captured overlapping images over a 3-kilometer radius, processed into a detailed 3D point cloud model providing immediate survey data for initial assessments. Complementing this, portable LiDAR 3D scanning offered precise information about physical obstacles, site topography, and geometric complexities. Collecting data outside the highway without disrupting existing traffic was more efficient than traditional surveying methods.
Figure 7: Digital technologies applied to the innovative erection method
A comprehensive BIM model incorporated digital data from both photogrammetry and LiDAR scanning, merging “reality capture” data with the virtual representation of the bridge structure. The BIM model created a powerful platform for analysis, simulation, and validation of the proposed construction methodology, Figure 7, facilitating collaborative planning and problem-solving.
Augmented Reality for verification
Augmented Reality (AR) was used for final on-site verification, Figure 8. The BIM data was overlaid onto the actual site environment using tablets, allowing the construction team to visualise planned SPMT movements and bridge deck installation in real-time. This AR visualisation provided a powerful tool for verifying the accuracy and feasibility of the digital plan, enabling virtual walkthroughs, identifying potential issues, and making necessary adjustments before actual operations commenced.
Figure 8: Augmented Reality applied to the innovative erection method
Design for Safety
Through collaboration among the client, consultant, contractor and subcontractors, we proposed several design-for-safety measures to enhance the safety margin of the innovative full-span bridge deck erection method.
Adoption of Gantry Crane
Figure 9: Adoption of gantry crane for precast deck segments lifting
Precast deck segments were cast in the Mainland, delivered to Hong Kong by vessel, and unloaded at Tuen Mun Public Cargo Working Area for subsequent land transportation to the on-site assembly yard. The use of a gantry crane at the assembly yard provided much greater stability during lifting compared to traditional mobile cranes, Figure 9.
Low-level transportation
The original plan was to transport the full-span bridge deck at a high level by SPMTs. However, after assessing the complex site conditions, especially tight spaces and sharp turns for the SPMTs, we adopted a much safer method of low-level transportation combined with lifting using the strand-jack lifting system (Figure 10) to minimise construction risks.
Figure 10: Adoption of low-level transportation by SPMTs
Telescopic supporting beam system
Figure 11: Temporary support lifting system
Since the full-span bridge deck needed to be temporarily supported over existing busy roads before being permanently connected to columns, we implemented an additional telescopic supporting beam system on top of the strand-jack lifting system, Figure 11. This resulted in two separate temporary supporting systems, each structurally adequate to support the full-span bridge deck. These two independent supporting systems provided double guarantee, which greatly enhanced site safety and prevented potential failures over busy roads.
Construction challenges
The innovative full-span bridge deck erection method faced various challenges including (i) complex temporary traffic arrangements for road closures; (ii) complicated site conditions for using the SPMTs; (iii) eccentric loads on the SPMTs due to the curved bridge deck; and (iv) tight construction timelines for nighttime work on major highways. As this was the first implementation of the full-span bridge deck erection method in Hong Kong, we began with the erection of the first and second full-span bridge decks located within the site area to gain experience. For the third full-span bridge deck which spans across the Fanling Highway, we conducted an on-site trial run to identify and rectify potential issues before proceeding.
First Full-span Bridge Deck Erection (daytime operation)
Figure 12: First Full-span Bridge Deck Erection
The first full-span bridge deck erection was completed on 2 February 2024 during the day (Figure 12), without the need for road closures given this section of the bridge was within the site area. For this first erection, the actual operation time exceeded the original planned time, prompting the construction team to explore ways to streamline the process, particularly surveying, to improve efficiency in subsequent operations.
Second Full-Span Bridge Deck Erection (night-time operation)
Figure 13: Second Full-Span Bridge Deck Erection
The second full-span bridge deck erection was completed at night on 11 July 2024, under similar arrangements (Figure 13) as the first operation but with a curved transportation path for the SPMTs. This erection aimed to determine whether the SPMTs could transport a 420-ton bridge deck through a tight space and within the allocated nighttime. It was observed that the SPMT took significantly more time than anticipated due to difficulties from sharp turns and uneven ground surfaces. The construction team conducted a thorough review before the upcoming third full-span erection which was the most challenging operation.
Third Full-Span Bridge Deck Erection - Trial run for the SPMT swept path across Fanling Highway
Figure 14: A Trial Run for the SPMT across Fanling Highway
A trial run for the SPMTs transporting an approximately 800-ton bridge deck across Fanling Highway was conducted before the actual implementation. This trial validated improvements from the first and second full-span bridge deck erections, verified counterweights for stability, and confirmed the digital simulation path for the SPMTs, Figure 14. In the trial run, the SPMTs navigated tight spaces with the most critical location of only about 800 mm clearances to existing structures and reached the designated erection point at Fanling Highway. Reference points for the SPMT swept path were recorded and marked, allowing the actual transportation of the third full-span bridge deck erection to be completed smoothly on 28 August 2024.
Stringent traffic restrictions
Figure 15: Night-time Full Closure of Fanling Highway
Another challenge was the erection of the bridge deck over the Fanling Highway and Castle Peak Road (Chau Tau Section) which were not only busy roads but also critical for cross-boundary traffic leading to Huanggang Port. This required careful planning of road closures and temporary traffic arrangements to minimise potential impacts, Figure 15. Due to the importance of these roads, stringent traffic restrictions limited bridge segment construction to one or two nights per week if using conventional balanced cantilever method.
To overcome these challenges, the innovative full-span bridge deck erection method was adopted, greatly reducing the number of nighttime road closures. With the full support of the Government authorities, full closure of Fanling Highway from midnight until 5:30 am on the erection day was allowed. The third full-span bridge deck erection operation was successfully completed in about five hours as planned.
Concluding remarks
CEDD is fully committed to advancing innovative and sustainable infrastructure developments that better serve the community. The innovative Full-span Bridge Deck Erection Method, coupled with digitalisation, enables faster and safer construction, reduces carbon emissions, and minimises public disturbance. It sets a benchmark for future bridge construction in Hong Kong.
This method sets a benchmark for future bridge construction in Hong Kong.
This innovative bridge construction method has received recognition internationally and locally, earning a number of awards as listed in Figure 16 below.
Figure 16: Awards for the implementation of “Full-Span Bridge Deck Erection Method”
Acknowledgement
CEDD would like to thank the consultant, AECOM Asia Co. Ltd., the contractor, China Road and Bridge Corporation, along with their subcontractors including bridge specialist VSL Hong Kong Ltd. and digitalisation specialist Tyfron Solutions Ltd. The collaborative efforts in utilising innovative bridge construction methods and digital technologies were instrumental in overcoming the challenges encountered throughout the Loop project in 2024. CEDD also wishes to acknowledge the invaluable contributions of all project stakeholders in support of this initiative.
Figure 17: Collaboration among client, the consultant, the contractor and specialists