Pick, Slew
and
Vertical
Lowering

A Total Solution in Temporary Steel Structure

Dino Spaleta
Chief Project Director

The synergy of our people, built upon technical engineering expertise and high-end facilities accompanied with high quality steel structure fabrication, has once again flagged our credentials as a total solution(s) provider. On this complex project, precision engineering and accuracy of works are the critical success factors. From planning to execution, we had complete trust in my team in terms of capability and due diligence.

Yuen Long Bridge Manoeuvre

Yuen Long Station Property Development YLTL No.510 involved a series of residential developments. Sanfield and MTR, the co-developers, attempted to extend the transportation network by linking up the old town to the newly developed area in Yuen Long. A passenger bridge and a vehicle bridge were designed to connect the residential site to the existing MTR station.

To alleviate potential disruptions to daily operation of public transport adjacent to the site, a “Slew and Lowering” erection method was adopted. The biggest challenge was to complete a rapid and safe installation in an extremely congested construction site and not once, but twice for the two (2) permanent bridges respectively. In which, rotation and lowering of the 2 bridges were carefully operating on top of high voltage (750V DC) overhead cables, without inducing any impact on the operation of light rails, transit trails and access to YL MTR station.

Goldwave was commissioned to material supply, fabricate, off site trial, build and erect a full set of temporary turntable steel structures to facilitate a specialized bridge rotation over a live rail line, including lowering and final installation and anchoring. To ensure maximum safety, the heavy-duty turntable frame and platform were anchored on top of a reinforced concrete podium. Our experience in precision engineering made it possible to meet a stringent specification based upon a complex structural and mechanical/hydraulic steelwork design, which was meticulously merged with the reinforced concrete structure. Together with world renowned Freyssient, our strategic partner, the bridge installation time durations were significantly reduced due safe and efficient working conditions that were carefully planned and executed by our project teams.

Project Summary

Passenger Bridge (length)
46m
Vehicle Bridge (length)
52m
Turntable Rotary Frame Diameter
21m
Main Frame Steelwork Weight
1,250T
Counterweight
1,150T

Stakeholders

Hospital Authority

Freyssient Hong Kong Limited

Ove Arup & Partners HK Ltd.

AGC Design Limited

Sanfield (Management) Limited

Award

Gold Medal, Award of Best Method Statement by Occupational Safety & Health Council

Project Types

CHALLENGES

“Is Bridge Rotation Feasible?”

During the tender consultation stage, we were asked to explore the technical concept of bridge rotation. As the idea was only in the conceptual stage, and required an extensive study before getting to the consensus and/or commencement of manufacture/build stage. For the purpose of transforming from a mechanical (hydraulic/electric) rotation to a vertical hydraulic lowering system, our expert engineering team proposed a convincing steel structure solution. For ease of installation, steel billets were adopted to act as counterweights for this technically demanding operation. Larger billets were used for the skid shoes and these were deployed to minimize distortion to the skidding system.

The 16-meter-long curved rail track components required the largest size machining equipment in its class to undergo an extensive and precise machining process. Our rigid quality control of tolerance(s) ensured a smooth skidding operation of the rotary frame.

Full Simulation in Our Jiangmen Fabrication Yard

To accurately assess both the functionality and installation of the turntable steel structure, we recommended running a comprehensive simulation in our Jiangmen factory located in southern China. After the trial, the large and complex structure would then be dis-assembled and then re-assembled on-site in Hong Kong.

The design was premised upon a series of inclined and diagonal members, which formed the complex geometrically round-shaped structure. A strict tolerance of 2 to 5mm was implemented for the assembling of the 21M circular structure and this was a not negotiable technical requirement. During the trial, 1150 Tons of steel counterweight were carefully placed on the turntable to simulate the actual operational loads. Furthermore, load testing equipment was established to accurately measure planned V’s actual movements during the trial run. Safety in design became our challenge for this robust operation, but given our due diligence regarding best safety practice, the risk(s) were mitigated.

Site Constraint

The construction site allowed absolutely no room for steel member storage. Therefore, from our Jiangmen factory to the Hong Kong site, the pre-fabricated components were delivered to the site in a just-in-time manner, and had to be installed on the same day. Logistics was a difficult task in terms of ensuring precise delivery time, including material loading, customs clearance and also difficult traffic conditions.

The location of where the bridges were, “mechanically / electrically slewed and lowered” was in close proximity to Light Rail Transit. All possible measures were carefully planned to minimize disturbance.

One Solution Caters for 2 Different Structure Systems

Onsite erection encountered not only the complexity of integration between structural steelwork and mechanical steelwork, but also connecting them to a heavy reinforced concrete spiral ramp structure.

Moreover, the entire steel structure was purposefully designed and built for horizontal rotation movement of a steel turntable supporting frame, which facilitated two (2) permanent bridges of measuring 46 & 52M each in length, and each bridge was installed over a two (2) night operation. During the erection phase, a dimensional cross check was carried out for both individual steel bridges along with the overall structure to avoid misfit or misalignment. Skillful welding and assembling/bolting, including diligent quality control measures, were used including regular surveys checks as a risk prevention measure to rid any potential errors.

SOLUTIONS

Ingenious Structure Design

We were engaged in the early design stage phase and we considered from the overall operation when formulating solutions. We also identified and divided them into different major components. Our Safe & Sounded structural system caters for :

a) interface between steel frame with irregular concrete structure

b) ensure the components are divided into the most effective size and geometry to suit logistics and crane capacity as well as enable the complex components to adjust to suit the “fit-up” on site.

c) rigid structure components enable it to provide stability and maintain precise geometry for the rotational operation.

d) the A-frame structure is designed in a multi-functional jig which enables for assembly of bridges structural frames, rotatory operation, vertical lifting, supporting heavy counter weight, design for rapid installation and demolition, able to adopt 2 different bridges design with 2 other structural systems.

Fabrication Makes a Difference

The successful trial at Jiangmen Factory demonstrated our capabilities of fabricating a very complex steel structure by using advanced technology machinery, high tech and powerful lifting equipment. Precise engineering, therefore, contributed to our strength in fabricating a wide range of high-quality products in a competitive and diverse marketplace

Just-in-Time Delivery

Due to a well-known shortage of storage areas in Hong Kong, particularly at the Yuen Long construction site, the logistics schedule has to be carefully planned to deliver all oversize and or large geometrically shaped segments from Jiangmen to Hong Kong on a just-in-time basis, premised upon a current and approved construction program.

On-site Erection

Mitigation of disturbance to the public was one of our major objectives. Acoustic barriers and vertical safety net barriers were used and or established.

As the Heavy Lifting system involved rotation of a temporary turntable supporting structure together with a permanent bridge, geometry accuracy in both assembled components including the overall structure was a critical hold point.

The erection relied upon highly skillful welding and bolting to minimize shrinkage and also any distortion generated by the welding process. Regular survey checks and fine-adjustments are done throughout the erection. To secure a safe and smooth rotation, tight survey and QA geometry controls are required to ensure a tolerance limit of 3-5mm is adhered to and this is an uncompromising task premised upon a large and complex 21-meter circular structure.

KEY DELIVERABLES

Higher Building Accuracy

Safer Operation

Shorter Erection Period

Mitigate Risk and Disturbance to Public

TEAM SHARING

This mega project was definitely a huge challenge from start to finish. Enormous effort was contributed in structural steel engineering and early design coordination to yield the best solution(s) that consist; Precision machining during fabrication phase, assembly / dismantling of the rotary frame, trial rotation under a rigid quality control process in our China factory, just-in-time logistics plan, hoisting of each mega steel section in busy traffic, tight site space for re-assembling, and the connection of large and heavy load structures into different levels of reinforced concrete structure zones that defines our commitment and credentials.

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