Project Description


Alex Kirkham – Great Britain

01335 362941


Drainage and Water Management

Box Culvert Brochure

FP McCann offers a bespoke headwall solution suitable for box culverts. These box culvert headwalls are made up of several precast panels and tied with an in-situ stitch.

NOTE: Our XL & XXL headwall range cover box culverts up to and including 2400mm x 2400mm sections.

Internal Dimensions (Based on flat invert culvert units)

Key: Flow area m²/ Discharge rate m³/sec


Please note: These figures are a guide only and will be dependent on the mould configuration used in manufacture. Discharge rates are calculated using Colebrooke-White equation for a fully wetted perimeter under uniform flow conditions and assuming a flat invert culvert unit. The assumed laying gradient (s) is 1:1000 with a roughness coefficient (k) of 0.3. Where different values may be required, please contact the office number below to discuss your specific requirements. The hydraulic design of a box culvert should always be undertaken by the overall scheme designer, as they can take into account the upstream and downstream conditions and other parameters such as freeboard, restriction due to silt build-up and need for the culvert to be free-flowing at all times. Due to the lack of this information, FP McCann will only give discharge rates for an idealised culvert, which may not suit the local conditions.