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Cobthorn Way Congresbury

Cobthorn Way Congresbury

Project Objective


Transportation, Highways & Drainage Engineering services to support the Planning Application for a major residential development.

Services provided:

  • Transportation and Traffic Advice
  • Transportation Assessment
  • Drainage Strategy
  • Flood Risk Assessment
  • Off-site highway design and liaison with North Somerset District Council.


Sunley Estates Ltd proposed a major residential development off Cobthorn Way Congresbury. This Planning Application was for the first significant development in the Parish for over 50 years.

The development comprised 54 houses with garages and parking spaces, a pumping station, sustainable drainage, landscaping, open space and informal footpaths.

Ample car parking would be provided throughout the site with an average of two spaces per unit. Secure cycle parking would be provided in line with North Somerset Council parking standards. Vehicle access to the development was to be from Cobthorn Way and the Application included proposals for off-site highway improvements in the local vicinity.


Off-Site Highway works to Wrington Lane proposed a priority give way and footway improvements near its junction with Kent Road. These measures would ensure that vehicle speeds were kept to a minimum and provide a safe crossing point for pedestrians. In addition, a new footpath was proposed extending the existing footway along the northern side of Wrington Lane.

The Transportation Assessment (TA) assessed the Highway Impact by considering the existing traffic flows in the area, adding the predicted TRICs traffic generation from the development, and distributed on the network. PICADY software was used to model the impact of AM and PM peak hour traffic flows at the nearby junctions to estimate the potential delays caused by additional traffic.

Consideration of Personal Injury Accident Data for the local area was also included in the Assessment.

The TA demonstrated that the proposed development would not be detrimental to traffic flows or road safety on the surrounding highway network, and that the proposed off-site highway improvements along Wrington Lane would provide additional road safety improvements.

With respect to sustainable transport, the TA confirmed that the site was in a sustainable location, maximising the potential use of local buses and trains to many locations in the area and region.

A Travel Plan would be implemented as part of this development proposal. The Travel Plan strategy aimed to reduce car usage, in particular the number of single occupancy vehicles travelling to the site by residents and visitors.

A Travel Plan pack would be provided to new residents with information that encouraged the use of public transport and promoted walking, cycling and car sharing as an alternative. A Travel Plan Coordinator would be appointed after the site was completed, to monitor and review the uptake of the strategy.

A sustainable Drainage Strategy was produced for the proposed development.

Local Environment Agency regulations required surfacewater run-off to the local watercourses from new developments to be limited to half of that from an equivalent greenfield site. Surfacewater volumes above this figure should be retained and attenuated within the site until the storm subsides.

Using hydraulic modelling techniques to meet the EA requirements, the drainage strategy proposed a system of ditches and ponds within the natural topography. Permeable surfacing was utilised to capture and manage the runoff.

Foul drainage would connect into the existing public sewer to the north of the site via a new pumping main.

A Flood Risk Assessment (FRA) was produced to submit with the Planning Application. The Environment Agency positioned the site within Flood Zone 1 with areas of Flood Zone 2 & 3 beyond and to the south of the development area.

The FRA identified the primary flood risk to be from fluvial flooding of the River Yeo. The FRA specified floor levels that would provide additional freeboard above 1 in 100 year + climate change flood prediction levels.

Other sources of flooding, such as groundwater, were investigated and shown to be of minimal risk.

The Flood Risk Assessment confirmed that the proposed development is appropriate and sustainable in the terms set out in NPPF.



Congresbury, North Somerset

Project status:

Completed 2016

Contact Us:

0333 700 4001