What Are the Components of Form Traveller?
A form traveller, also known as a flying form, is a specialized construction system used in the construction of bridge decks, viaducts, and other structures where the construction of large concrete spans is required. The form traveller moves along the bridge deck as construction progresses, supporting the formwork for pouring concrete and providing a platform for workers and equipment. To understand how a form traveller functions, it's essential to examine its key components:
1. Main Girders
The main girders are the primary structural components of the form traveller, spanning the width of the bridge deck. They provide the framework for supporting the formwork and distributing the loads from the concrete pouring process. Main girders are typically made of steel or a combination of steel and concrete, depending on the design requirements and span length.
2. Cross Girders
Cross girders are secondary structural members that connect the main girders and provide additional support for the formwork. They run perpendicular to the main girders and help distribute the load evenly across the form traveller. Cross girders are also made of steel and are spaced at regular intervals along the length of the form traveller.
3. Formwork
The formwork is the temporary mold or structure used to contain and shape the freshly poured concrete until it hardens and achieves sufficient strength. In a form traveller system, the formwork is mounted on the main girders and cross girders and moves along with the traveller as construction progresses. The formwork is typically made of plywood, steel, or aluminum and is designed to withstand the pressure exerted by the concrete.
4. Hydraulic Jacking System
A hydraulic jacking system is used to raise and lower the form traveller along the length of the bridge deck. This system consists of hydraulic cylinders or jacks mounted on the main girders, which exert vertical force to lift the traveller and move it to the desired position. The hydraulic jacking system allows for precise positioning of the formwork and ensures uniform concrete placement across the entire span of the bridge.
5. Walkways and Access Platforms
Walkways and access platforms are provided on the form traveller to allow workers to access the formwork for installation, maintenance, and concrete pouring activities. These walkways are typically located along the sides of the main girders and provide a safe working environment for construction crews. Access platforms may also be provided at regular intervals to facilitate equipment placement and material handling.
6. Electrical and Control Systems
Electrical and control systems are integrated into the form traveller to automate its operation and ensure safety and efficiency. These systems may include motor drives, sensors, and programmable logic controllers (PLCs) to control the movement of the traveller, monitor critical parameters such as formwork alignment and concrete placement, and provide real-time feedback to operators.
7. Safety Features
Safety features are incorporated into the form traveller to protect workers and equipment during construction activities. These features may include guardrails, handrails, safety harness anchor points, emergency stop buttons, and warning lights. Additionally, safety protocols and procedures should be established and followed to minimize the risk of accidents and ensure the safe operation of the form traveller.
By understanding the components of a form traveller and their functions, construction professionals can effectively utilize this specialized construction system to efficiently and safely build large concrete structures such as bridge decks and viaducts.
