Importance of independent checking for bridges

Lessons learned - my experience worldwide

Having spent years as a third-party checker for over a hundred bridges worldwide, such Qatar, Vietnam, India and Finland, I have gained first-hand insights into the complex challenges faced by bridge engineers. Vietnam stands out in my experience, not only for its ambitious infrastructure projects but also for the recurring design and execution issues that sometimes hinder progress. Projects like the Thang Long Expressway with Binh Khanh and Phuoc Khanh bridges highlight the need for stringent quality assurance practices to prevent costly errors and delays. Despite financial constraints and tight timelines, the potential to improve design reliability through independent checks remains immense.

Principles of independent checking

The core philosophy behind independent checking is to ensure impartiality, competence, and comprehensive oversight of structural designs. The key principles include:

• Independence: The checking entity must be completely separate from the design team to avoid conflicts of interest. This guarantees unbiased assessment.
• Competence: Checkers should possess in-depth experience in bridge engineering and structural analysis to detect nuanced errors effectively.
• Scope: The review should encompass all technical aspects, from load analysis and material selection to structural safety under various conditions.
• Documentation: Findings must be clearly documented, including any proposed corrective measures. The emphasis is on precision and actionable feedback.
• Follow-up: There should be mechanisms to track the implementation of corrections, ensuring compliance and reducing long-term risks.

These principles aim to uphold safety, durability, and efficiency in bridge construction, which is especially vital for rapidly developing regions like Vietnam.

Global practices in independent checking

Countries around the world have adopted stringent practices to ensure the safety and quality of bridges:

• Finland: The land use and building act mandates independent checking for highly demanding projects. The focus is on safeguarding structural integrity and addressing potential risks like fire safety and environmental challenges.
• Sweden: Trafikverket oversees the inspection of bridge designs, adhering to strict national standards. The approach emphasizes consistent quality control.
• Norway: The Norwegian Public Roads Administration enforces robust procedures to review designs, aiming for long-term resilience and safety.
• Germany: In Germany, bridge checks are integrated into the permitting process, governed by local authorities and adhering to precise engineering standards.
• United States: The Federal Highway Administration provides detailed guidelines for design review, with each state potentially adding its own requirements. This layered approach ensures adaptability while maintaining a high safety threshold.

The variety of practices demonstrates a shared commitment to excellence, albeit tailored to each country’s regulatory environment and risk landscape.

Classification of bridge complexity and corresponding checks

Bridge designs are typically categorized into three levels based on their complexity and the intensity of the checks required:

Basic check

1. Suitable for simple structures.
2. Focuses on verifying basic calculations and ensuring compliance with standard design codes.

Detailed check

1. Applies to moderately complex designs.
2. Involves thorough analysis of technical details, including load paths and material behavior.

Independent check and analysis

1. Reserved for high-risk or highly complex bridges.
2. Conducted by an independent team, reviewing all calculations, modeling, and assumptions.

These categories ensure that the effort invested in checks is proportional to the risk level, optimizing resources while maintaining safety.

Common errors detected in independent checks

Independent checks often uncover critical issues, such as:

• Calculation mistakes: Miscalculations in force directions or load analysis can severely impact a bridge's stability.
• Modeling errors: Incorrect or overly simplistic models may lead to unreliable results. Inadequate model validation is a recurring problem.
• Omitted considerations: Sometimes essential analyses, like seismic response or thermal expansion, are overlooked due to a lack of awareness.
• Material misuse: Inappropriate material selection or failure to consider corrosion protection can compromise longevity.
• Geometric inaccuracies: Misalignments or incorrect profiles affect load distribution, impacting overall performance.
• Inadequate joint and interface design: Poor detailing at joints or supports can hinder a structure’s flexibility and cause failures under stress.
• Environmental oversights: Neglecting the impact of local hydrology or wind conditions can result in severe erosion or destabilization.

Identifying these issues early prevents costly retrofits and enhances the bridge's long-term performance.

My observations and experiences

In projects with well-defined quality assurance and adherence to independent checking protocols, major issues have been rare. However, I have witnessed projects where cost-cutting measures and experimental designs led to significant problems. Notable examples include:

• Misaligned forces: I encountered cases where load vectors were wrongly oriented, severely compromising stability.
• Flawed models: Structural models were sometimes inadequate, with results accepted uncritically.
• Neglected analyses: Vital assessments, like wind load analysis for cable-stayed bridges, were sometimes omitted due to a lack of expertise.

My role as a checker has often involved advocating for better understanding of design fundamentals and emphasizing the need for critical review of analysis outcomes.

Recommendations

Rapid infrastructure development necessitates a robust framework for design verification, especially in fast developing countries such Vietnam. Based on my experience, I recommend the following:

• Adopt a categorized checking system: Classifying bridges by complexity and assigning appropriate levels of independent checks would streamline resource allocation and enhance safety.
• Enhance training and competence: Investing in specialized training for engineers would reduce common design errors and increase awareness of critical analyses.
• Implement standardized procedures: Uniform guidelines for documentation, follow-up, and compliance would prevent inconsistencies and promote accountability.
• Foster a culture of safety and innovation: Balancing innovative designs with rigorous safety checks is essential. Pilot projects could help refine approaches before full-scale implementation.

By learning from global best practices and adapting them to local conditions, Vietnam and other developing countries can achieve safer and more durable bridges, fostering long-term economic growth and public trust.