Aylesbury Culvert Replacement

Overview 

Shortlisted in the Ground Engineering Awards 2024

Background: 

The Aylesbury Culvert Replacement project epitomises Ayesa's dedication to engineering excellence, sustainability, and community safety, highlighting our expertise in addressing transportation infrastructure challenges. Located under the Chiltern branch line in Buckinghamshire, the brick arch culvert represents an uncommon instance where the culvert was constructed before the railway line, that runs over it—a reversal of the usual construction order. The culvert is essential for water management from the Grand Union Canal's Aylesbury arm.

In January 2023, the structure partially failed, necessitating an immediate response to ensure the railway's stability and to plan and execute an appropriate repair strategy. Positioned in a challenging location, there was also a critical need to keep the train services operational until a suitable possession window could be found for the culvert's replacement. Ayesa, in collaboration with J Murphy & Sons and Network Rail, was brought on board to design the permanent solution, marking a pivotal phase in ensuring the infrastructure's safety and reliability for the future.

Our role:
Ayesa's involvement in the Aylesbury Culvert Replacement project was initiated at a crucial juncture, focusing on the design of the permanent works. After the initial response to the culvert's failure, which included a temporary over-pumping and propping solution to maintain rail service continuity, Ayesa was tasked with crafting a durable and sustainable design for a new culvert. Our role as the Permanent Works Designer was instrumental in transitioning from immediate, short-term measures to a long-term solution that not only addressed the structural requirements but also embraced environmental considerations.

Collaborating closely, Ayesa crafted a design for a new precast concrete culvert. This design not only replaced the deteriorated structure but also integrated environmental considerations to prevent flooding and enhance local biodiversity. The implementation of rock and coir rolls, along with Flex MSE retaining walls, showcases our commitment to environmentally responsible engineering, addressing potential increases in water velocity and promoting habitat creation.

The hydraulic complexities of the project, compounded by sediment accumulation and the risk of flooding to nearby properties, required meticulous planning and coordination with the Environment Agency. Our solution, underpinned by thorough water modelling studies, ensured the new culvert's design would not exacerbate local flood risks, demonstrating our team's holistic approach to infrastructure challenges.

The project's execution phase, conducted during a meticulously planned 12-day railway closure, highlighted our team's efficiency and collaborative spirit. Removing over 1200 tonnes of spoil and replacing the old structure with 18 precast concrete units, we not only restored but significantly enhanced the resilience of the railway infrastructure. The seamless reinstatement of the railway tracks post-project underscores our commitment to minimizing disruption and maintaining the vital flow of goods and passengers.

Over a 12 day railway closure, Network Rail, Murphys and Ayesa completed the following works:

• Remove track and the old brick-built drainage culvert
• Install a new 18-section pre-cast concrete culvert using a 300 tonne crane
• Replace 700 metres of rail and 85 sleepers
• Upgrade three sets of points which are movable sections of track, allowing trains to move from one line to another.

Furthermore, the incorporation of a steel sheet pile wall, faced with seeded Flex MSE bags, into the project design reflects our innovative approach to blending functionality with environmental stewardship. This feature not only supports essential access but also fosters biodiversity, enhancing the local ecosystem.

Value Add:

1. Innovative Design Solutions: Our design for the new precast concrete culvert showcased Ayesa's innovative approach, integrating advanced features such as rock and coir rolls along with Flex MSE retaining walls. This not only ensured structural durability but also addressed hydraulic and environmental challenges effectively. This project sets a new standard in civil engineering with the installation of a modern precast concrete structure designed to last 120 years and enhance local biodiversity.

2. Environmental Sustainability: By incorporating environmentally sensitive design elements, we mitigated the risk of increased water velocity and potential flooding to nearby properties. Our design promoted biodiversity and habitat creation, underscoring our commitment to ecological considerations in engineering projects.

3. Collaborative Stakeholder Engagement: Meticulous planning and coordination with the Environment Agency and other key stakeholders were pivotal. This ensured the project's execution was informed by a comprehensive understanding of environmental implications, aligning with regulatory and community expectations.

4. Infrastructure Resilience: Our work on the project played a critical role in enhancing the resilience of a crucial piece of infrastructure. By prioritizing not only the structural integrity of the culvert but also its environmental impact and sustainability, we contributed to safeguarding the railway's operational integrity for the future.

5. Efficient Project Management: The project's successful completion within the constraints of a tightly scheduled railway closure demonstrated Ayesa's proficiency in efficiently managing complex projects. Our ability to minimize operational disruptions while executing substantial infrastructure improvements highlights our expertise in delivering on time-sensitive initiatives.

6. Long-term Community Safety and Infrastructure Reliability: By ensuring the long-term resilience of the Aylesbury Culvert, our project contributes to community safety and the reliability of critical transportation infrastructure. This aligns with Ayesa's broader goal of enhancing public infrastructure through sustainable and innovative engineering solutions.