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Flexible Pavement Design in Brighton

Practical geotechnics, field-tested.

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Brighton sits on a chalk bedrock that drains fast but crumbles under repeated wet-dry cycles. The sea spray along the A259 and the salt-laden air from the English Channel accelerate asphalt stripping and binder oxidation. A flexible pavement design in Brighton has to account for this aggressive microclimate, not just traffic loads. We model granular subbase layers that work with the chalk's high permeability, preventing water from pooling at the formation level. The CBR road investigation provides the stiffness input that defines layer thicknesses, ensuring the pavement withstands both the seasonal tourist influx on the seafront and the constant bus traffic through the North Laine. Without a site-specific design, you risk premature fatigue cracking within the first five years.

A flexible pavement on Brighton's chalk must handle rapid drainage and salt attack simultaneously; the subbase design makes or breaks the whole section.

Our service areas

Methodology and scope

Our approach to a flexible pavement design starts with a dynamic cone penetrometer survey across the site. Brighton's geology shifts from White Chalk Subgroup to Clay-with-Flints deposits within metres, especially around Hollingbury and Patcham. We log the DCP blows per 100 mm to compute the CBR profile, then input the values into a multi-layer elastic model using software compliant with DMRB CD 225. The bituminous binder grade is selected for the site's specific solar radiation and low winter temperatures, with a focus on preventing thermal cracking on exposed sections like the Brighton Bypass. Bitumen modifiers such as SBS polymers are specified where heavy goods vehicle counts exceed 500 per day. Every design is backed by a laboratory testing programme that validates the mix's resistance to permanent deformation and moisture damage according to BS EN 12697-22 and BS EN 12697-12.
Flexible Pavement Design in Brighton
Technical reference — Brighton

Local considerations

Along Brighton's seafront, we regularly see pavements where the surface course has stripped from the binder course because the aggregate-binder bond failed under saltwater exposure. The root cause is often a design that did not incorporate an anti-stripping agent or specified a generic binder for a coastal site. When the pavement sits on Clay-with-Flints, differential settlement between the clay and adjacent chalk lenses creates longitudinal cracking within two winters. A flexible pavement design must include a lime-stabilised capping layer in these transition zones. We also mandate a minimum 3% crossfall on all carriageways to shed water before it infiltrates the granular layers, a detail often overlooked on flat car parks near the marina.

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Applicable standards

DMRB CD 225 – Design for New Pavement Construction, DMRB HD 26/06 – Pavement Design and Maintenance, BS EN 12697-22 (Wheel tracking test), BS EN 12697-12 (Water sensitivity), BS EN 12591 (Paving grade bitumens)

Technical parameters

ParameterTypical value
Traffic class (Million Standard Axles)Up to 80 msa (HD 26/06)
Foundation classClass 2, 3 or 4 (CD 225)
Design CBR (%)2 – 15 (site-specific)
Bituminous binder grade40/60 or PMB (BS EN 12591)
Asphalt base stiffness modulus (MPa)3,500 – 7,000
Granular subbase permeability (m/s)≥ 1 × 10⁻⁵
Design life (years)20 – 40

Frequently asked questions

What asphalt mix is best for Brighton's coastal roads?

A 40/60 pen polymer-modified bitumen (PMB) with an approved anti-stripping agent. For heavy-duty sections like the A23 approach, we specify a 10 mm close-graded surface course over a high-modulus binder course.

How much does a flexible pavement design cost in Brighton?

A full design package, including site investigation and mix validation, ranges from £1,240 to £4,050 depending on the site area and traffic class. Small car parks sit at the lower end; trunk road designs with multiple sections require the full scope.

Do you handle pavement designs for small private car parks?

Yes. Even for a 20-space car park in Kemptown, we apply the same DMRB principles but scale the investigation. A reduced DCP grid and one set of laboratory tests is usually sufficient to produce a solid design.

How long does the design process take?

Site investigation and DCP testing are completed in one day. The laboratory programme takes 10 to 12 working days. We deliver the final pavement design report within three weeks of site access.

Location and service area

We serve projects across Brighton and surrounding areas.

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