Coronation Road Culverts

Project Management & Site Superintendence, Structural Design
he new culvert crossing over the main Waroona Drain (asset owned by Water Corporation) was part of the bridge widening scheme on the original precast beam construction.

WML Consultants were engaged by the Shire of Waroona to undertake design development, project manage Tender and undertake Site Superintendent duties on the project. Construction costs were also developed for the project as a method to assess the competing tenders on the project.

Dr Nicholas Mills was engaged as the Senior Structural engineer for the project and coordinated the design with the Civil design team from WML Consultants. Dr Mills was the site superintendent on the project coordinating project construction between the Principal and the main Contractor. NRM consultants acknowledge the input of WML Consultants, Charles Hull Contracting and the Shire of Waroona in the successful implementation of this project.


Several solutions had been presented to the Shire of Waroona on the widening of the existing bridge on Coronation Road. Further design options were requested by the Shire of Waroona to develop a cost-effective scheme. The construction budget was estimated at $1.2m. The project was delivered in the timeframe required and the costs indicated by the Consulting Engineer. The construction and the design had to consider the existing design water flows through the channel and maintain that flow through the construction and no loss of capacity on the system as the local agricultural land relied heavily upon this main drain for irrigation. Several issues came to light on the site such as high ground water from penetration of the existing clay layers during the excavations. Existing telecoms lines were severed during excavation due to service cables located in the wrong position by Telecoms sub-contractor. Reinforcement costs were error and these had to be managed during the contractor and appropriate variances paid to the contractor and their sub-contractors.


A traditional multi barreled Culvert system, apron slab, wing wall and concrete embankment were chosen as the appropriate solution for this project. The Culverts were fabricated by Permacast, with local contractors for the concreting and construction.

The drainage channel was designed by the Civil Team to provide appropriate channel capacity. The structural team provided retaining walls and culvert design to provide the appropriate structural robustness to accommodate the expected vehicle traffic. Head beams were added to the construction to provide barrier restraint.

Dr Mills provided Super-intendent duties on the site providing coordination of costing, variations both design and costing variations, site meetings and programming. Dr Mills ensured that the appropriate testing and compliances on the construction were undertaken by the contractor during the construction.


The final project was delivered a little behind schedule but with no disruption to traffic flow or Shire programme. The costs of the project were within the estimated budge despite the variation due to ground water and the need for dewatering systems.

The project is currently under the one year maintenance period after construction. We do not anticipate any significant issues to come to light on the project.