Introduction
EC Engineers was engaged by a well-known insurance builder to complete a bridge design for a driveway culvert crossing in the Moreton Bay region. Damage had occurred to the bridge during the Brisbane floods in 2022 and the structural integrity of the bridge then became undermined due to water runoff. The client had grave concerns the current bridge was on the brink of collapse.
Methodology
Prior to commencement of the bridge design for the culvert crossing a number of prudent steps were required. A cadastral land surveyor was engaged to develop a contour of the culvert. This contour was used to profile the land, catchment and water flow path.
Secondly, a soil tester was engaged to complete sampling and testing and provide a report outlining the results. The soil test displayed underlying soil strata’s and conditions to enable construction of new foundations for the culvert structure.
Once the contour had been developed and soil test results were finalised, we were then ready for our Structural Design Engineer to prepare a design of the replacement culvert. A full suite of design drawings was provided to our client which detailed reinforcement scheduling, concrete and erosion control.
Furthermore, we collaborated with a specialist contractor to provide hydrologist modelling as required by the local council. The overflow assessment included:
- Review of the detailed site survey and proposed design, and check for completeness and potential impacts.
- Determination and interrogation of hydrology catchments.
- Rational method calculations to develop a conceptual understanding of subcatchment flows and the hydrological regime.
- XP-SWMM modelling to determine, peak discharges, to confirm rational method estimates. Developed in accordance with Queensland Urban Drainage Manual (QUDM), Australian Rainfall and Runoff (ARR), and current Council policy and guidelines.
- Assess existing culvert configuration and proposed configuration to demonstrate surrounding properties are not adversely affected.
- Produce an Overland Flow Assessment Report outlining the findings and certification by an RPEQ that the as constructed culvert will not cause adverse effects to adjoining property.
- Produce a Final Overland Flow Assessment Report to be submitted to council.
Solution/Outcome
Design of a bridge for a culvert crossing is a complicated process requiring a number of specialist contractors and project management. EC Engineers was able to coordinate this process and take the burden off our client. EC Engineers used our specialist knowledge and project management skills to oversee the Cadastral Surveyor to develop a contour of the culvert. Furthermore, a soil tester was sourced to provide critical information regarding the soil type which is needed for the design.
A thorough set of engineering plans was then developed and provided to our client to ensure the construction of the bridge could commence as soon as possible. Lastly, in accordance with council regulations EC Engineers coordinated the process of hydrologist modelling to provide an overflow assessment. Many engineering companies would be overwhelmed by the complex nature and number of specialist contractors required. EC Engineers is well equipped to take on this challenge and successfully completed this project well within desired timeframes.
