Project History: Laser survey and 3D model required to inform development decisions
Originally constructed in 1898 as a purpose built asylum for the mentally ill, the Goodmayes Hospital site in Romford, Kent had been earmarked for development. Many of the buildings were disused and stood vacant with only a small number still used by the NHS for outpatient services.
C A Design Services was approached by architects Ingleton Wood to produce a survey and 3D model of the site, which could be used to inform development decisions. These included identifying which existing buildings to retain, as well as understanding the impact that new structures could have on the locally listed façade and aesthetic.
The Challenge: Topographic and laser survey of vast 10 hectare site
The site was vast, covering approximately 10 hectares. The hospital was originally designed with centrally located support services and detached wards linked via a network of corridors. This design is known as a Compact Arrow layout, commonly described as a Pavilion System.
For this project, our survey team was commissioned to produce both 2D plans of the original hospital buildings and site topography. We also produced a 3D model of the entire site including interior modelling of the buildings that were due to be retained. This meant that interior and exterior models and 2D plans were required of a total of 10 buildings. Exterior models were required of a further 20 buildings, along with an array of link corridors, ancillary areas and adjacent building elevations.
Our Approach: Combination of laser and traditional survey techniques used due to sensitive nature of site
Given the sensitive nature of the site, we took a variety of approaches in order to accurately measure and record the required survey information. Externally and internally in a number of vacant buildings, 3D laser scanners were used to measure and photograph the buildings/rooms. This approach was unsuitable where buildings were still occupied, so we used traditional hand measurement to avoid potential disruption to patients and staff.
The survey took a total of two weeks on site, with up to five surveyors on site at any one time.
We took approximately 600 scans in total having established a control network on site to ensure these scans were accurately positioned. This involved taking the coordinates of the natural and artificial targets and linking these with the targets within the scans.
The Outcome: LOD3 model of historic building facade
Once back in the office, the scans were linked together in a process known as registration, producing a point cloud of the site and buildings. Using this point cloud, Autodesk Revit® was used to create the 3D model. A LOD3 model was produced detailing the original historic buildings facades that will be retained. Internally a LOD2 model was adopted as more extensive development is proposed internally.
Approximately 8 weeks were spent modelling the site, often with multiple surveyors working on the model simultaneously. Along with the model, traditional 2D CAD plans were produced. These were constructed using information from both hand measurements taken on site, and information extracted from the point cloud.
CADS’ technical knowledge and professionalism delivered significant value to this project
“We employed CADS Survey team on this complex and sensitive project because of their technical knowledge and professionalism. The project required the integration of laser captured point cloud data and hand measured data to create the 3D model and CADS delivered this within the agreed timescale and budget.
While we had to allow an additional 30% in the budget for the delivery of the 3D model over the 2D drawings, this has delivered significant value to this project, particularly where we have been able to make fully informed design decisions not only on the location of buildings but also on the impact on the facade and view.
CADS took a very consultative approach to the project, fine tuning the specification for the model to ensure we were able to swiftly integrate it into our design process once it was released and we have been delighted with the result.”
Simon Jones – Head of Estates Strategy and Major Capital Developments, North East London NHS Foundation Trust