Precast Box Culverts
We design and manufacture bespoke concrete box culverts to order, tailored for drainage, access, and water management needs.
Precast Box Culverts
Box culverts provide a robust, low-maintenance alternative to in-situ construction. A smooth mould finish improves hydraulic performance, while the interlocking spigot-and-socket joint ensures fast alignment and reliable sealing.
Each unit is engineered to meet project-specific loading, flow, and structural requirements, ensuring suitability for a wide range of infrastructure applications. Optional features can be incorporated to enhance functionality, including mammal ledges for wildlife passage, V-channels and formed flow channels for improved water management, as well as twin run configurations where higher flow capacity or wider crossings are required.
Culverts are designed to accommodate project specific loadings, exposure, and design life. This flexibility makes them suitable for a wide range of applications, including beneath heavily loaded structures, providing a durable and dependable solution for long term drainage and water management.
Made To Order
Manufactured to your required width, height and loading
Fully Customisable
With flow channels, mammal ledges, headwalls and more
Fast Installation
Nationwide delivery, culvert systems arrive ready for quick installation
Flow Channels and more Bespoke Options Available
Common Applications
Common applications include:
- Road and Highway Crossings - Used to carry water beneath roads and highways while supporting heavy vehicular loads and maintaining long-term structural stability
- Attenuation & SuDS Applications - Integrates into Sustainable Drainage Systems (SuDS) to provide attenuation and controlled surface water discharge
- Railway and Transport Infrastructure - Installed beneath railway lines and transport corridors to safely convey water while meeting strict loading and safety requirements
- Agricultural Drainage - Helps manage field drainage and water movement across farmland, preventing water-logging and protecting access routes
- Stormwater and Flood Management - Provides efficient conveyance of stormwater and surface runoff, helping reduce flood risk and improve site drainage
- Industrial and Commercial Developments - Supports drainage infrastructure in large-scale developments, ensuring reliable water management around buildings, yards, and access roads
- Pedestrian and Service Underpasses - Can be configured to create safe passageways beneath roads or embankments
Customisable Culvert Options
Box culverts can be manufactured with a range of additional features:
- Mammal ledges: cast into the culvert to enable wildlife to pass safely above the water level
- Flow channels: half-round channels cast into the base, available in multiple sizes
- Twin run configurations: for separating water flow from dry access routes
- U-on-U configurations: units stacked to form increased internal heights or bespoke access solutions, ideal for larger hydraulic capacity or multi-functional use such as combined water flow and access routes
- DWF/V-channels: Integrated channels formed within the invert to concentrate low flows, maintaining self-cleansing velocities and reducing silt build-up during periods of low water flow
- Headwalls & wing walls: supplied to match culvert opening dimensions
- Open culverts with cover slabs: ideal for cable channels or maintenance access routes
Product Specifications
Concrete: High-strength structural concrete (typically C50 or as required)
Selected to deliver long-term durability and performance in line with project conditions and design criteria.
Finish: Smooth internal finish
Designed to optimise hydraulic performance and minimise maintenance requirements.
Design life: Up to 120 years
Engineered for long-term use in accordance with relevant design standards and site conditions.
Material density:
Dependent on concrete specification and design requirements to ensure structural stability and load-bearing performance.
Loading capacity: Designed to suit application
Units are engineered to accommodate project-specific loading conditions, including highways, rail, and other infrastructure.
Reinforcement cover: In accordance with design requirements
Detailed to meet durability, exposure class, and relevant British and Eurocode standards.
Key Benefits
Precast box culvert solutions offer a highly efficient and reliable method for managing water flow and supporting infrastructure.
- Bespoke Sizing - Culverts can be manufactured in a range of sizes and configurations to meet specific hydraulic requirements, ensuring optimal water flow capacity and site compatibility
- Strength & Durability - High compressive strength reinforced concrete
- Fast Installation - Precast units arrive ready for installation, significantly reducing construction time, site disruption, and the need for extensive on-site labour or curing periods
- Factory Controlled Manufacturing - Produced in controlled factory environments, each unit is manufactured to precise standards
- Longevity - Designed to withstand harsh conditions, precast culverts offer a long service life with minimal maintenance
Precast construction allows box culverts to be installed quickly and efficiently, significantly reducing on-site labour, programme durations, and weather-related delays.
Expert Knowledge, Design and Installation
Why Choose Unbrako?
We understand that no two drainage or infrastructure projects are identical. That’s why we offer fully bespoke culvert solutions tailored to:
- Hydraulic design requirements
- Ground conditions
- Load classifications
- Environmental considerations
- Site access constraints
- Programme timelines
Our team works closely with engineers, contractors, and developers to deliver practical, buildable, and compliant solutions.
From small drainage schemes to major infrastructure developments, Unbrako Precast Concrete LTD provides durable, engineered culvert solutions built for long-term performance.
How To Order:
Our full culvert range can be ordered directly from our sales team. We offer a site visit and design service for every project if required and are also available to assist with technical advice.
For more information, please fill in the enquiries form using the button below, or call 01949 860 985 and a member of our sales team will be happy to help. Alternatively, email Daniel@unbrakoprecast.com for direct technical support on your project.
