Bridge Jacking in Practice: Lessons from the Xiayan Highway Elevation Project in Shanghai

A real-world reference for high-capacity hydraulic cylinders and synchronized jacking systems in bridge engineering

In large-scale bridge erection engineering, jacking an existing structure is rarely just a matter of lifting capacity. Alignment control, safety redundancy, and synchronization accuracy often determine whether a project proceeds smoothly or turns into a high-risk operation.

The elevation of the Xiayan Highway North Bridge in Shanghai offers a useful bridge project case study. The project involved lifting a long-span structure under complex slope conditions, while operating directly beneath an active expressway. From an engineering standpoint, it highlights why hydraulic jacking systems for bridges must combine high load capacity with mechanical safety mechanisms and precise control.

Project Background: Constraints That Defined the Jacking Strategy

According to publicly available project disclosures, the Xiayan Highway reconstruction formed part of the Shanghai Rail Transit Airport Link Line diversion works. The North Bridge section alone presented several non-negotiable constraints:

• Bridge section length: approx. 1.29 km (within a total corridor of 1.82 km)
• Jacking scope: 180 m segment between piers Pmn02–Pmn10
• Longitudinal slope variation:One end adjusted from 3.5% to 4.94%; The opposite end shifted from –97% to 4.03%
• Site limitation: sections Pmn06–Pmn08 located directly below the G1503 Expressway, requiring uninterrupted traffic safety

From a construction management perspective, this ruled out segmented lifting or tolerance-heavy methods. A whole-span synchronized hydraulic jacking approach became the only viable solution.

Jacking Method Applied: Hydraulic Lift with Mechanical Safety Redundancy

The project adopted a combined hydraulic jacking + mechanical follower protection method. In practice, this meant hydraulic cylinders carried the load during lifting, while mechanical systems ensured the structure could be physically locked at every stage.

This approach is increasingly common in EPC bridge projects, especially where elevation height, urban constraints, and safety accountability intersect.

Jacking System Configuration (Summary)

A lift of this scale places sustained stress not only on cylinders, but also on synchronization accuracy and locking reliability.

Equipment Considerations: Why Cylinder Design Matters

In bridge applications, high-capacity hydraulic cylinders must do more than lift. They must operate predictably within a synchronized hydraulic control environment and maintain safety margins even during power loss or pressure fluctuation.

Double-Acting High-Tonnage Cylinders for Controlled Adjustment

For loads in the 500T range, double-acting hydraulic cylinders are typically preferred. Unlike single-acting designs, hydraulic retraction allows:

• More controlled descent during height adjustment
• Faster repositioning between lifting stages
• Improved alignment correction when slope tolerances are tight

This makes them particularly suitable for bridge jacking operations involving longitudinal slope changes rather than purely vertical lifts.

Mechanical Lock Nut Cylinders: Reducing Dependence on Hydraulic Pressure

A key risk in high-elevation jacking is hydraulic drift—small pressure losses that translate into unacceptable vertical movement. This is why mechanical locking solutions are increasingly specified.

A Double Acting Mechanical Lock Nut Hydraulic Cylinder integrates load-bearing threads directly into the cylinder body. Once the target elevation is reached, the mechanical nut is engaged, transferring the load from hydraulic pressure to a solid steel-to-steel connection.

For bridge erection work, this offers two clear advantages:

• A safety factor exceeding typical 1.5× hydraulic-only systems
• Stable load holding during inspections, adjustments, or temporary shutdowns

From an engineering risk standpoint, mechanical locking is no longer optional for complex urban bridge lifts.

Key Engineering Challenges and How They Were Managed

High Lift Heights and Lateral Stability

Raising a structure nearly 9.5 meters introduces increasing lateral sensitivity. Even small angular deviations can amplify stresses across bearings and piers.

In similar bridge jacking scenarios, engineers typically mitigate this by combining high-tonnage cylinders with articulated or tilting saddles, allowing minor angular accommodation without load concentration.

Synchronization Under Live Traffic

Operating beneath the G1503 Expressway left no tolerance for uneven lifting. A centralized PLC-based synchronized hydraulic control system was essential to maintain lift-point deviation within sub-millimeter limits.

This level of synchronization is a defining requirement for any hydraulic jacking system for bridges used in dense urban environments.

Project Outcomes and Practical Takeaways

The Xiayan Highway North Bridge elevation demonstrates what is achievable when load capacity, control logic, and mechanical safety are treated as a unified system:

• Zero safety incidentsthroughout the jacking operation
• Millimeter-level slope correctionacross the lifted span
• Improved construction efficiencycompared with staged demolition and replacement

For bridge contractors and EPC teams, the takeaway is straightforward: modern bridge construction methods demand integrated hydraulic and mechanical solutions, not standalone lifting equipment.

Planning a Bridge Jacking Project?

If your next project involves high-elevation lifting, synchronized control, or operation under live infrastructure, selecting the right hydraulic jacking system for bridges is critical to both safety and schedule control.

Explore solutions designed for these conditions:

• Double Acting High Tonnage Hydraulic Cylinders
• Double Acting Mechanical Lock Nut Hydraulic Cylinders
• Intelligent Frequency Conversion Control Synchronous Lifting Hydraulic System

Contact KIET Hydraulics to discuss system configuration, safety redundancy, and capacity planning for your bridge project.

Disclaimer: This analysis is based on publicly available information related to the Shanghai Xiayan Highway project and is provided for technical reference only. KIET Hydraulics was not the equipment supplier for this specific project.