Client: Dún Laoghaire-Rathdown County Council
DBFL were engaged by Dún Laoghaire-Rathdown County Council to deliver the detailed design of this road infrastructure project forming part of the wider Cherrywood SDZ development, providing civil and structrural design services as well as acting as Employers Representative.
Part of the wider Cherrywood Strategic Development Zone which aims to construct approximately 8,000 new homes in South Dublin, the Druids Glen Road Phase 2 project involved the design and construction of a new road extending from Phase 1, at the existing N11 junction to the east, and connecting into Lehaunstown Lane to the west. The works included the design and construction of 380 metres of single lane carriageway in greenfield with a new 43m long, three span bridge over the Cabinteely stream. The road will service new housing developments and will eventually be extended to provide pedestrian, cycling and vehicular access to the Cherrywood SDZ. The road design took direction from the TII, DMURS and the National Cycle Manual as well as DLRCC guidance developed as part of the Cherrywood SDZ.
The Phase 2 works included site clearance and enabling works; a new 43m bridge over the Cabinteely Stream; 380m of new road pavement, footpaths and cycle tracks; a surface water drainage system with Sustainable Urban Drainage and two attenuation ponds; new utilities and services including a strategic watermain, communications and electrical ducting, and a gasmain; and landscaping works.
There were difficult site conditions and challenges that informed the design and construction of Druids Glen Road, particularly in relation to the site topography. The road was primarily constructed between two waterways, the Cabinteely stream and the Carrickmines River, and had to negotiate the steep gradients of their valleys. The road’s vertical alignment was optimised to provide the minimum gradients possible to assist cyclists, pedestrians, and motor vehicles travelling along the road.
Another challenging area of design was the positioning of an attenuation pond on the side of the valley next to the Cabinteely stream. Due to the steep slopes of the valley, and with no option to move the pond to a more suitable location, the design team worked to maximise the holding volume of the pond while limiting the overall footprint, maintaining minimal slope gradients, and creating an area of ecological merit through appropriate landscaping. The pond design also included the provision of an adjacent shared footpath and cycleway facility that will link to the future Cabinteely greenway. The design produced satisfied the requirements of the CIRIA guidelines, access and mobility standards, and the planning conditions.
Further to the attenuation ponds provided as part of the scheme, Sustainable Drainage Systems (SuDS) were incorporated into the design to manage rainwater runoff from the road and protect the two receiving water courses from flooding and pollutants. These included flow control devices, petrol interceptors, infiltration trenches and tree pits.
Project Director
