Bridge Design and Assessment Consultancy

How do we evaluate a aging bridge without drawings? When I was a junior engineer, I was once assigned to a project to demolish an overpass that was over 40 years old(Cheonggyecheon viaduct in Korea). I remember we didn’t have any of the necessary information such as blueprints or material specifications so we had to carry measuring tapes, climb up on a cherry picker, and measure the dimensions of the bridge section by section to complete the project. This is a video of a recent aging bridge collapse in China. The safety evaluation of aging bridges must be conducted periodically, and a detailed diagnosis is especially essential to identify potential defects. For bridges without design documents, this detailed diagnosis must be performed through rigorous field measurements and a Reverse Engineering approach, following the procedures below. Detailed Diagnosis & Technical Evaluation Procedure - Geometry Restoration (As-built Generation): The absolute priority is direct and precise field measurement using tape measures and surveying instruments to understand the structural framework. Then, 3D laser scanners and drone photogrammetry are utilized as supplementary tools to digitize the overall geometry and generate drawings. - Material Property Investigation (NDT & Destructive Testing): Non-Destructive Testing (NDT) like GPR must be accompanied by destructive testing. This includes concrete coring to verify actual compressive strength and direct chipping of critical sections to quantitatively check rebar spacing and corrosion levels. - Static & Dynamic Load Testing: Restored dimensions alone cannot guarantee the load-bearing capacity. Real-vehicle load testing using dump trucks must be conducted to measure the bridge's actual behavior (deflection, strain) for verification. - Structural Analysis & Rating: Performing Finite Element Method (FEM) analysis based on the collected field data to evaluate the load-carrying capacity. Applicable International Codes In a global project delivery environment, the following international standards are applied to ensure the reliability of the evaluation. - AASHTO MBE (Manual for Bridge Evaluation): Standards for load rating and material testing of bridges without drawings. - ISO 13822 (Assessment of existing structures): Performance-based procedures and reliability verification for assessing existing structures. - FHWA Guidelines: Guidelines for detailed inspection and field sampling, including coring. The most critical question is: "How much additional safety factor is applied when evaluating based on data estimated without drawings?" In short, the code mandates a system that translates the risk of information scarcity into a structural safety margin.

💼 My Success Stories – Chapter 3: Kashmir Bridges (Preliminary Design Stage) Continuing my journey with ESS-I-AAR Consultant, I’m excited to share my contribution to the Kashmir Bridges Project, where I was involved in the preliminary design of 13 bridges for the Azad Government of the State of Jammu & Kashmir (CDO Muzaffarabad). Set against complex terrain and demanding site conditions, this project focused on developing efficient, constructible, and performance-driven bridge systems. 🔹 Project Highlights: • 13 Bridges (8 Single-Span, 5 Multi-Span) • Prestressed I-Girder & Integral Bridge Systems • Span range: 40 m to 110 m • Designed under AASHTO LRFD 2007, WPHC & HL-93 Loading 🔹 My Role & Technical Contributions: At the preliminary stage, I worked on structural modeling, analysis, and system development, including: • Grillage modeling for deck behavior • Substructure modeling (abutments, piers, foundations) • STAAD.Pro V8i (grillage + line + substructure models) • Load distribution and structural response evaluation 🔹 Custom Design Tools & Engineering Modules: To enhance accuracy and efficiency, I developed custom Excel-based design sheets, integrating key bridge design components and checks, including: • Prestress losses (stage-wise evaluation) • Stress checks at critical stages • Flexure, shear, torsion & bursting reinforcement (evaluated at every 10th point along the span) • Deflection under service loads • Bearing pad design • Deck continuity & ledge beam design 📊 Additionally, dedicated calculation modules were prepared for: • Material summary & load cases • Bridge load combinations • Wind & braking forces • Active earth & seismic pressures (abutments) • Longitudinal forces & stream flow effects • Scour depth evaluation • Vertical & lateral earth pressures • Wing wall and retainer block design This structured approach ensured that even at the preliminary stage, the design was data-driven, scalable, and ready for seamless transition into detailed design. Designing bridges here felt like composing a structural symphony, where loads, geometry, and materials all had to play in perfect rhythm. Proud to contribute to infrastructure that connects communities and supports long-term development. #BridgeDesign #StructuralEngineering #Infrastructure #PreliminaryDesign #ESSIAAR #KashmirProjects #CivilEngineering #STAADPro #AASHTO #BridgeEngineering #PrestressedGirder #ExcelEngineering #EngineeringInnovation

Good afternoon friends What i have experienced and learned over time regarding design of a bridge is that you need to have the following information correctly determined and interpreted for the structural engineer to do a good job of design. 1. Hydrological and Hydraulics should be accurately calculated. It is important to always compare the calculated water levels with the historical flood line/local high flood level knowledge. Correct scour depth design/calculation is key for the stability of the pier and abutment. Scour is worst for piers.... 2. Geotechnical investigation/drilling borehole loggings at the position of the piers and abutments are key. The boreholes should be superimposed to the foundation as demonstrated for accurate identification of the firm strata or different strata for determining the design information. 3. Topographical survey/profiles and sections of OGLs are key including the final road formation level from geometric design. 4. ESIA and RAP can also be key factors in ensuring success of such design. 5. The strata information can guide the engineer whether the foundation can be spread or deep/pile(friction or end bearing) 6. For both spread and pile, be mindful of soil structure interaction for good modeling and analysis output. 7. Be aware of the bearing capacity values at various depths as they can be good indicators for founding the bridge substructures. Also important to note is the SPT-N values, they too can guide on the founding level. 8. Abutments and wingwalls including the connections between the wingwalls and abutment should be modelled, analysed and properly designed. We always get supprised with premature failure of the wingwall-abutment junction/joints. The big question is, why??. 9. Magenta colour is silted river bed and the green is the river bed. GI and Materials data require some sort of interpretation to be clear on factual data for use by the engineer.