The story of the Macao Bridge

By The Macau Institution of Engineers*

*China Civil Engineering Construction Corporation is thankfully acknowledged to be the provider for this article’s materials and sources. Please see the end of this article for the reiteration of this acknowledgement.

The Macao Bridge is the fourth cross-sea bridge connecting the Macao Peninsula and Taipa Peninsula, located east of the Friendship Bridge. Proceeding from the eastern side of the new reclaimed area of Macao (Zone A), it connects with the artificial island of the Hong Kong-Zhuhai-Macao Bridge, crossing the Outer Harbour Channel and leading to the Inner Harbour Channel, landing at Zone E1 of the Macao new reclaimed area.

The mainline of the bridge spans approximately 3.085 km, including a cross-sea section of around 2.86 km, featuring two navigation span bridges. The main bridge is 1,370 m in total length, with a central span of 280 m. A hub interchange is set in Zone A, and an elevated bridge is reserved in Zone E1 for future connection with the Taipa Grande Tunnel. The bridge design includes eight traffic lanes, with two of them dedicated to motorcycles. Through the installation of wind barriers, the bridge enables safe vehicle passage along the mainline even during typhoon signal No.8. Serving as a crucial element in Macao’s transportation network of the future, the Macao Bridge also provides a vital route for dispersing traffic flow from the artificial island of the Hong Kong-Zhuhai-Macao Bridge. This project is of great significance, both for further strengthening the transportation connection between the Macao Peninsula and Taipa and Coloane, and for facilitating residents’ commute.

The owner of the Macao Bridge project is Direcção dos Serviços de Obras Públicas (DSOP) of the Macao Special Administrative Region. The supervisory entity is Arup Engineering Consultants Ltd/Macau Professional Consultants Ltd. The general contractor is the consortium of China Civil Engineering Construction Corporation, China Railway Construction Major Bridge Engineering Bureau Group, OMAS Construction Engineering. Lastly, the design unit is Tongyan Lin International Engineering Consulting (China).

Figure 1: Location layout of the Macao Bridge

Figure 2: The layout of the Macao Bridge

Figure 3: Elevation layout of the main approach bridge of the Macao Bridge

Figure 4: Cross-section layout of the main bridge of the Macao Bridge

Project design overview and innovations

Design overview

The design scope of this project is entirely bridge structures, with no roadbed section design. The entire bridge includes Area A and the port overpass, the north approach bridge, the north and south main bridges, the south approach bridge, and Area E A ramp bridge.

The main girder structures, bridge piers, abutments, and foundations of this project are all concrete structures. For the main girder structures, the E-Zone A ramp bridge has a concrete box girder design, while the remaining sections, except the main bridge, adopt steel box girders. The main bridge incorporates a combination of steel truss and steel box girder structures. The main bridge is configured in two sections, with spans arranged as 2×(202.5 m+280.0 m+202.5 m) = 1370.0 m. The cross-sectional layout comprises: 6.25 m (pipeline area) + 12.75 m (carriageway area) + 3 m (truss area) + 6.5 m (motorcycle lane) + 3 m (truss area) + 12.75 m (carriageway area) + 4.15 m (pipeline area), totaling 48.4 m in width.

Structural innovation of the main bridge

The main bridge adopts an innovative inclined steel truss and steel box girder combination, moving the trusses to the centre between the carriageways, connecting them with top crossbeams to form an integrated structure. In this approach, the load-bearing is concentrated within the core areas of the steel box girder and truss, thereby enhancing stability, aesthetics, and structural efficiency. Material usage and economic viability are also optimised in comparison with conventional steel truss bridges.

Figure 5: Conventional steel truss bridge vs. inclined steel truss-box girder combination bridge

For the main bridge’s steel truss–steel box girder, a variable cross-section design was adopted, with the truss forming an undulating, curvilinear shape. The design of this bridge draws its inspiration from Macao’s unique aquatic environment, abstracting the graceful contours of ocean waves into spatially undulating truss curves. Together with the reflection on the water surface, this composition creates a picturesque scene that harmonises natural beauty with a sense of modernity.

The main bridge’s composition creates a picturesque scene

that harmonises natural beauty with a sense of modernity.

Figure 6: Night view of the main bridge

Extensive application of high-strength steel

High-strength steel is employed extensively in the project, with the main bridge requiring about 49,000 tons, including Q420-grade steel for the steel box girders and Q690-grade steel for the compression zones in the trusses’ edge spans. Approximately 40% of the main bridge’s steel volume consists of Q500- and Q690-grade steel.

Figure 7: Main bridge material distribution map

Design challenges and solutions in strong wind conditions

Located in a coastal region subject to strong winds, especially during typhoon seasons, the Macao Bridge faced significant stability challenges. Optimisation measures, including adjustments in truss layout and modifications to the wind barrier design, were tested through sectional and full-bridge wind tunnel tests. Data indicated that, under maximum surrounding wind speeds of 32.5 m/s (equivalent to typhoon signal No.8), the wind speed on the bridge’s mainline was successfully reduced to meet the No. 3 signal standard.

Figure 8: Wind tunnel test of the main bridge

Figure 9: Main bridge full-bridge aeroelastic model test

Project construction overview and innovations

Construction conditions

The Macao-Taipa Fourth Bridge Project connects Taipa, Zone A of the new reclaimed area, and the artificial island of the Hong Kong-Zhuhai-Macao Bridge. The region features a subtropical maritime monsoon climate, influenced by tropical cyclones and typhoons. The surrounding waterway is a major passageway of the West River, with a flat seabed and tidal data showing a maximum high tide of 2.98 m and a minimum low tide of -1.78 m. Additionally, the bridge spans the Macao Channel and the Outer Habour Channel, with height restrictions imposed by aviation and water depth, and lateral constraints from the Outer Habour Channel, Macao Channel, marine outfall pipelines, and breakwaters. These factors add complexity to the construction of the substructure, steel girder hoisting, and equipment selection.

Given the project’s complexity, different construction methods were employed for different steel girder sections. The key approaches included large-segment lifting for the main bridge, shoring and sliding for the two shore-adjacent spans of the south approach bridge, and multiple techniques— such as small-segment shoring, sliding, small-segment pushing, large-segment shoring, and bracket shoring—adopted for the mainline and ramp bridges to address the spatial interferences between the Zone A interchange substructure and steel girder installation.

Comprehensive use of full casing-clean water bore piling techniques

The project adopted, on a large scale, a full-casing bore pile method for penetration into the bedrock, using clear water to create the pile structure. The piles were large in diameter and deep, with maximum diameters of Φ3.0 m and depths reaching nearly 113 m. The steel casing encountered complex stress and deep embedding requirements, needing to penetrate cover layers and weathered granite over 30 m thick and embed for at least 0.3 m into the bearing layer of weathered granite, with a total embedding depth of approximately 90 m.

The key factors in pile formation included pile sinking equipment, pile sinking technique, and steel casing structure. Common equipment and techniques for sinking steel casing piles include vibrating hammers, hydraulic impact hammers, static pressure sinking, and full rotation rigs or rotary casing machines for cutting and driving the casing into the geologic strata. However, due to the large diameter and depth of the Macao Bridge casings, as well as adverse geological conditions such as weathered granite and isolated boulders, the vibrating, impact, and static sinking methods were unsuitable. Consequently, a specifically designated full-rotation rig model was selected as the primary sinking equipment. The casing was driven into the mid-weathered rock surface by coordinating a full-casing full-rotation rig/ rotary casing machine with a grab bucket/rotary drill for soil removal, followed by reverse circulation drilling (RCD) that bores through rock, clearing with water before placing underwater concrete to form the pile.

Figure 10: Full-casing full-rotation rig construction site

Development of a 2,200-ton dual L-shaped boom heavy-lift vessel for large-segment steel girder hoisting under complex conditions

The main bridge side span girders, north and south approach bridge girders, and Zone A interchange girders were all erected with offshore lifting of large segments. A total of 72 segments were installed, with the heaviest one exceeding 2,000 tons. With a bridge location near the Macao International Airport, an aviation height restriction of +60.00 m was imposed on the construction area, and the steel box-truss girder had a cross-sectional width of up to 48.4 m. To address the installation challenges that were posed by height limits and complex water conditions, a dual L-shaped boom heavy-lift vessel, with a lifting capacity of 2,200 tons, was specially designed for the Macao Bridge. This domestically pioneered vessel design features two boom phases built on the same hull, permitting interchangeable L-shaped and straight booms. Phase 1 provides a lifting height of 52 m to meet the height restrictions of Macao Bridge, while Phase 2, with a lifting height of 110 m, accommodates other projects in which there is the need to lift more highly. This equipment serves as a core asset in large-scale bridge construction.

Figure 11: 2,200-ton dual L-shaped boom heavy-lift vessel hoisting site

Customised multi-style front-support deck crane for large-span girders

For the installation of the main bridge’s central span steel girders, a deck crane capable of handling segments, weighing nearly a thousand tons, was utilised. When cantilevering, the crane’s front supports are distributed across four points on either side of two adjacent transverse diaphragms on the front end of the already installed segments. The exterior front supports are uniformly positioned at the intersection of the inclined web of the steel box girder and the transverse diaphragm, while the interior supports have three variable configurations to accommodate the central span’s tapered section steel truss girders: pedestal support on the lower chord longitudinal girder at the transverse diaphragm, cover support on the lower chord node plate of the steel truss girder, and beam support on the adjacent lower chord longitudinal girder at the truss girder node plate. The crane moves along tracks, utilising multi-style front supports based on the installed segment configuration to hoist the central span girders. This support system optimally distributes reaction forces, maximising the load-bearing capacity of the existing structure, suitable for the cantilever assembly of central span steel girders in steel box-reinforced under-deck truss bridges.

Figure 12: Customised deck crane hoisting site for thousand-ton central span steel truss

Leveraging digital technology for project precision management

The application of digital intelligence integration takes the diffusion of digital intelligence technology as its basic fulcrum and the use of data elements as its internal form. In this way, such an application achieves a leap in productivity within the industrial system and is a representative form of new quality productivity. Generally speaking, the construction industry is facing many issues and is in a bottleneck and transitional period towards high-quality development. Considered in this light, digital transformation becomes an urgent matter.

Figure 13: Building Information Modelling (BIM) management platform for the Macao Bridge project

In the Macao Bridge project, there are numerous points and long lines, with simultaneous and cross-operation processes, rendering construction organisation difficult and posing severe challenges to overall project risk prevention and control. To ensure that on-site management is efficient, controllable, safe and green, the Macao Bridge project innovatively uses Building Information Modelling (BIM), “3D laser scanning + virtual assembly”, Virtual Reality (VR)/ Augmented Reality (AR), simulated interactive digital twins, and other technologies to achieve innovative applications such as 3D work guidance, scheme comparison, and progress simulation display. Through the establishment of a digital construction management platform system, management will be made intelligent and information transparent, effectively improving the level of refined management. The project adopts a visual smart construction site management model and invests in a variety of smart devices to provide real-time warnings for unsafe operating behaviours and abnormal conditions on site, reduce management risks, and effectively ensure site safety.

The project adopts a visual smart construction site management model and invests in a variety of smart devices to provide

real-time warnings for unsafe operating behaviours and abnormal conditions on site, reduce management risks, and effectively ensure site safety.

Figure 14: Application of digital twin simulation technology

Conclusion

On 1 October 2024, the Macao Bridge officially opened to traffic. As a people’s livelihood project that is commonly anticipated by the residents of Macao and an important transportation infrastructure adjacent to the Hong Kong- Zhuhai-Macao Bridge, the Macao Bridge, now completed and opened, not only improves Macao’s urban transportation layout, but also creates more convenient travelling conditions for residents and tourists. It is of great significance that Macao be assisted in its growth as an international tourism and leisure centre and that moderate and diversified economic development be continuously promoted in it. As a project that pays tribute to the 75th anniversary of the founding of New China and the 25th anniversary of Macao’s return to the motherland, the Macao Bridge will surely become a new landmark in Macao and add luster to its social and economic development.

Acknowledgements

China Civil Engineering Construction Corporation provided the materials and sources of this article.

Figure 15: Opening status of the Macao Bridge