a) Traditional Formwork

• Description: Uses timber or plywood supported by scaffolding or steel props.
• Applications: Small-scale or less complex bridge components like abutments, piers, or short-span decks.
• Advantages: Low cost, flexible, suitable for small projects.
• Disadvantages: Labor-intensive, time-consuming, not suitable for large or repetitive structures.

b) Modular/Formwork System (Steel/Aluminium Systems)

• Description: Prefabricated panels made of steel or aluminium.
• Applications: Pier caps, decks, and abutments.
• Advantages: Reusable, faster assembly, high-quality finish.
• Disadvantages: Higher initial cost, mechanical handling.

c) Cantilever Formwork (Balanced Cantilever Method)

• Description: Used when bridge segments are cast in-situ in a balanced manner from a pier.
• Applications: Long-span bridges over water or deep valleys.
• Advantages: No need for ground-based falsework, suitable for inaccessible locations.
• Disadvantages: Complex engineering.

d) Incremental Launching Formwork

• Description: Bridge superstructure is cast in segments in a stationary formwork and pushed/“launched” longitudinally over piers.
• Applications: Straight or slightly curved bridges.
• Advantages: Suitable for difficult terrain, limited site disruption.
• Disadvantages: Requires careful alignment, high precision needed.

e) Form Traveller System

• Description: Equipment used to support formwork for casting bridge segments in a balanced cantilever construction.
• Applications: Cable-stayed and cantilever bridges.
• Advantages: Reusable, adjustable, efficient for long spans.
• Disadvantages: complex to operate.

f) Climbing Formwork

• Description: Mechanized system that climbs upward as construction progresses.
• Applications: Bridge towers or pylons (e.g., cable-stayed or suspension bridges).
• Advantages: Safe and efficient for tall vertical structures.
• Disadvantages: Limited to vertical elements.

g) Tunnel Formwork (used in box girder bridges)

• Description: Steel formwork that forms the deck and walls in one operation.
• Applications: Box girder bridges.
• Advantages: Fast construction, smooth finishes, repetitive use.
• Disadvantages: Less flexibility for non-standard designs.

Box girder formwork is a reusable steel molding system specifically designed to create box-shaped concrete structures, such as bridges and buildings. This formwork system consists of outer and inner molds, as well as bottom and end molds, all configured to form the hollow, enclosed cross-section of the box girder. The purpose of box girder formwork is to provide a precise, stable, and high-rigidity mold for the concrete, ensuring the structural integrity and quality of the final box girder component.

Box girder formwork is a specific type of bridge formwork designed to create the hollow, box-shaped structural element of a box girder bridge. While all box girder formwork is bridge formwork, not all bridge formwork is box girder formwork; bridge formwork is a broad term for any temporary mold used in bridge construction, which can be for various structural elements like decks, piers, or different types of girders.

Box girder formwork offers several advantages in bridge construction, particularly for long-span and high-load bridges. Here are the key benefits:

a) High Strength and Load-Bearing Capacity

• Box girders have a closed-cell structure, providing excellent resistance to torsion and bending.
• Ideal for curved or skewed bridges where torsional forces are significant.

b) Efficient Use of Materials

• Optimized design allows for less material usage compared to solid sections for the same strength.
• Lightweight for the given structural capacity, helping in cost-effective construction.

c) Aesthetic and Slim Profile

• Box girders can be designed with a clean and smooth underside, offering an aesthetically pleasing appearance.
• Slim profiles are ideal for urban or architectural settings .

d) Better Durability and Protection

• The enclosed shape protects internal components like post-tensioning tendons from weather and corrosion
• Suitable for harsh environments, such as coastal areas

e) Versatile Construction Methods

• Compatible with segmental construction, cast-in-place, or precast techniques.
• Adaptable to incremental launching, balanced cantilever, and span-by-span methods, making it versatile for varied site conditions.

f) Safety and Stability During Construction

• The closed box section offers greater stability during erection, reducing the risk of deformation or collapse.
• Formwork systems can be pre-assembled and reused, improving construction speed and worker safety.

g) Economical for Repetitive Structures

• Particularly cost-effective for repetitive spans, as formwork can be reused multiple times
• Reduces labor and formwork costs on longer projects

Box girder formwork supports load-bearing capacity by: Using a geometrically efficient box shape for stiffness and load distribution.Employing strong materials and well-braced structures to resist construction loads.Transferring loads safely to the ground or supporting structures.

Bridge shuttering refers to the temporary framework or formwork used to support the concrete during the construction of a bridge until it gains sufficient strength to support itself.

• • Shuttering is a type of formwork specifically designed to mold and support cast-in-place (in-situ) concrete until it hardens and gains enough strength.
• • In bridge construction, shuttering is used to shape and support elements like:
  • • Bridge decks
  • • Beams/girders
  • • Piers
  • • Abutments

In box girder formwork, hydraulic systems provide powered adjustments for precise alignment, controlled stripping of the formwork after concrete curing, and the ability to adapt to various beam shapes and sizes, significantly improving construction speed, reducing labor costs, and ensuring high-quality, accurate surface finishes in precast bridge construction.

Bridge shuttering and slab shuttering are both types of formwork used in concrete construction, but they differ significantly due to the nature, scale, and structural requirements of the elements they support.

Improper bridge formwork installation can lead to serious safety hazards, structural deficiencies, and financial consequences. Here are the main risks:

a) Structural Failure

• Collapse of the formwork during concrete placement due to insufficient strength or stability can result in the entire bridge or a section failing.
• Premature removal or poor support can cause the fresh concrete to crack, deform, or collapse under its own weight.

b) Worker Safety Hazards

• Improperly installed formwork can collapse unexpectedly, endangering workers with falls, crushing injuries, or fatalities
• Loose or unstable platforms also increase the risk of accidents during construction.

c) Poor Structural Integrity

• Misalignment or movement of formwork can result in:
  • Uneven or misaligned bridge elements
  • Honeycombing or voids in the concrete
  • Weak points that may compromise the bridge's long-term performance or safety

d) Delays and Cost Overruns

• A collapse or failure can halt construction, requiring costly rework, material replacement, and investigations.
• Repairing or replacing damaged sections increases both time and financial costs

e) Non-Compliance with Design and Codes

• Improper installation may not meet engineering specifications or building codes, leading to legal liability, fines, or the need for redesign.

f) Environmental Risks

• If a collapse occurs over a water body or environmentally sensitive area, it can lead to pollution, legal violations, or ecological damage.

Summary Table:

Risk Category	Examples
Structural Failure	Collapse, deformation, cracks
Safety Hazards	Worker injuries, fatalities
Integrity Issues	Misalignment, weak concrete, honeycombing
Cost & Time	Rework, delays, legal disputes
Compliance	Violation of codes or engineering standards
Environmental Impact	Debris in rivers, soil contamination

Ensuring proper design, material selection, skilled labor, and regular inspections is critical to avoiding these risks