Girdering and regirdering of bridges involves replacing or adding new girders, which are the main load-bearing beams, to either new or existing bridge structures. This process is crucial for bridge maintenance, upgrades, and new constructions. Erection of new girders can be done during new line construction or when replacing existing ones during traffic blocks.

Girdering/Regirdering Process:

Planning and Design:

This involves assessing the existing structure, determining the required girder type and size, and developing a suitable erection or replacement plan.

Girder Fabrication:

Steel girders are typically fabricated off-site in a girder yard, often using welding or bolting techniques.

Launching/Replacement:

Various methods can be used for launching new girders or replacing existing ones, including:

• In-situ erection: Assembling the girders directly on the bridge supports.
• Side slewing: Moving girders into position using temporary supports like cribs or trestles.
• Crane erection: Utilizing cranes to lift and position the girders.
• Specialized rail-mounted systems: Employing gantries or other rail-based systems for girder transport and placement.

Temporary Arrangements:

During regirdering, temporary arrangements like cribs, trestles, or trollies are often used to support the existing structure and facilitate the replacement process.

Fastening and Connections:

Once in position, the girders are securely fastened to the bridge supports and connected to other structural elements like stringers.

Track and Rail Work:

After girder replacement, the track and rail system is reinstated, including any necessary adjustments to the rail level.

Final Inspections:

Thorough inspections are conducted to ensure the structural integrity of the bridge and the proper functioning of all components.