Adoptable Road Design.

This case study reviews an adoptable road and drainage design to the local highway authority and water authority standards. The site was a former bus depot and is classed as a brownfield site based within a small settlement, making it ideal for residential redevelopment.

Site Constraints

The major constraint with the site was presented a surface water exceedance flood risk from a culvert laying upstream of the site. During high periods of rainfall, parts of the site and adjacent road would flood causing concerns for this development.

How We Approached The Design

With the flood risk constraint in mind, Berrys developed an innovative and efficient design solution to ensure the new houses would not be at risk of flooding. The site access road was designed to collect and convey flood water, which will then flow into an exceedance channel, which lead into the brook running adjacent to the lowest part of the site. All site levels were designed to rise up from the road.

Berrys produced a detailed design package for the adoptable roads, drains and sewers. A sustainable drainage design was developed to collect and attenuate water for the 1 in 100 year plus 35% climate change event, whilst flows off site were reduced by at least 50% below existing run off rates to meet Local Lead Flood Authority guidance. The design was developed and modelled using the latest Causeway Flow hydraulic design software.

The main driver with the design was approaching it with a holistic view, to ensure that a brownfield site could be developed to meet the local affordable housing need. Berrys future-proofed the drainage system to cope with demands of a future phase 2 development on the site for employment units.

For information and assistance with your adoptable works designs please contact Richard Harman.