Project Description
The existing Gravel Pit Car Park at the Royal Cornwall Hospital site in Truro is being extended to provide a further 181 staff parking spaces. The project forms a key part of the enabling works for the new Women and Children’s Hospital building. Consulting engineers Arup and contractors BAM Construction collaborated with ABG to design a more sustainable and cost-effective solution to retain the earthworks at the western edge of the new parking area and to accommodate a 3.5m height difference.
The Challenge
The extension of the gravel car park required significant earthworks, including an 82m long x 3.5m high earth retaining structure and an adjacent 30m long access ramp. A reinforced concrete design would look too imposing against the surrounding countryside and be expensive and time-consuming to construct, whilst incurring a much heavier carbon footprint to transport to site. A vegetated earth retaining option was preferred for aesthetic reasons, especially given the height and length of the slopes required. Additionally, the Trust wanted to minimise costs by reusing all site-won fill material.
The Solution
The ABG Webwall System (partly geogrid-reinforced) formed the 70° slopes along the 82m long section in order to maximise the number of parking spaces. The Webwall solution is supplied in light-weight, easy to transport panels that are unfolded and expanded into position to quickly form each layer of the structure prior to backfilling.
ABG Webwall
The ABG Abslope EM system was installed for a 30m long access ramp at the southern end of the site, joining at 90º to the Webwall. The Abslope EM system incorporates multiple layers of geogrid to reinforce the earth embankment, with a vegetation liner at the face of the slope to enable grass / vegetation to establish. ABG’s gravity and reinforced earth retaining solutions enabled the use of site-won fill in order to construct the earthworks with a natural vegetated finish. This approach greatly eliminated off-site material disposal costs and reduced the environmental impact of the project.
The ABG Service
ABG’s design and supply service included detailed calculations, construction drawings and a fully indemnified project proposal.
