An erection plan for bridge girders is a detailed scheme outlining how to move shop-manufactured girders and secondary structural components from the site to their permanent configuration during bridge construction. The scheme outlines the sequence of erection steps, equipment used (such as cranes), and logistical considerations for safe and efficient girder placement. This plan is crucial for ensuring the bridge is constructed as designed, meeting structural, safety, and project-specific requirements.
Factors Influencing the Erection Plan
Several critical factors influence the development of an erection plan/methodology:
Site Logistics: Site accessibility for transporting steel girders and space availability for crane assembly and movement are key considerations. Restricted access, limited staging areas, or challenging terrain can significantly affect the erection method and sequence.
Crane Access and Lifting: The choice, capacity, and positioning of cranes are central to the erection scheme. The site layout, crane reach, and girder weight and length determine the crane size and if crane lifting is a feasible approach (or another method such as launching is preferable), need for temporary works how and when girders will be lifted and placed.
Temporary Works: The volume and cost of temporary structures required. If conventional crane erection necessitates expensive intermediate piers, bents, or trestles, it may be more advantageous to consider launching or moving pre-assembled spans.
Erector's Experience and Preferences: Erectors often bring unique expertise and preferred methods based on past experiences. Their practical knowledge of steel erection can influence crane selection, lifting techniques, and operation sequence.
Traffic Closures and Restrictions: Work over or near existing roads, railways, or waterways may require access restrictions, necessitating coordination with local authorities for temporary closures or controlled environments for crane operations.
Cost, Risk, and Schedule: Balancing cost-effectiveness, risk minimization, and schedule adherence are key concerns. The erection plan must optimize these factors to ensure the project remains on budget and is completed on time.
The bridge designer is responsible for ensuring at least one feasible erection method exists and including an assumed construction staging in the design. The steel erector and their erection engineer, in collaboration with the general contractor, develop the final erection methodology, which may differ from the designer's assumed method provided it stays within design limitations.
While the erection sequence typically doesn't significantly impact design or structural performance for most girder bridges, exceptions exist. For instance, the 199A Viaduct on the Golden Ears Project required the designer to incorporate the erection sequence into their structural analysis due to its crucial impact on design calculations. See article Constructability in Bridge Design #5 - Consideration of a Feasible Erection Methodology in Bridge Design.
Collaborative Process
Developing the final erection method is a collaborative effort involving the erector, erection engineer, and general contractor, often with input from the designer and other stakeholders. This collaboration ensures the chosen method meets safety, efficiency, and design requirements while adapting to the project's unique constraints.
In summary, an erection scheme is crucial to bridge construction planning, shaped by both engineering principles and practical, site-specific challenges. The steel erector and their team craft the step-by-step sequence, ensuring girders are safely and effectively erected in line with project goals.
Spannovation's Expertise in Bridge Erection Planning
At Spannovation, we excel in developing comprehensive and tailored erection plans for bridges. Our expertise encompasses specialized development of custom erection plans and close collaboration with erectors and contractors. We bring extensive experience in various heavy lifting techniques, including single, tandem, and three-crane operations, crane-assisted and incremental launching, lateral slides, and progressive and balanced cantilevering.
Our diverse experience enables us to go beyond simply applying calculations to client ideas; we actively contribute to the brainstorming process, offering innovative solutions and serving as a knowledgeable sounding board for our clients. Furthermore, our familiarity with local standards, submission processes, and approval requirements across various jurisdictions (including BC, AB, MB, and ON) ensures smoother project execution and compliance, making Spannovation a valuable partner in bridge construction planning and execution.
Sample Projects:
Comments