GIFA Surveys – 32 ESFA PSBP2 Schools, ~250,000m²
Capturing large areas of the school estates as part of the ESFA PSBP2 school building programme core surveys required a different approach to the traditional disto based survey method.
During 2017 the second phase of the priority schools building programme has accelerated. SUMO have been providing both the Utility/Topographic and the gross internal floor area core surveys. This case study describes a new innovative use of mobile scanning to capture data much faster than was previously possible and the use of BIM software to create a coordinated set of drawings and schedules for each project.
- The number and scale of schools requiring survey has mean that the historic approach of surveying during school holidays was not suitable.
- Traditional methods of survey produce CAD output but non-graphical data cannot be added and so has to be coordinated manually
How they were overcome
- Using hand held laser scanning we captured the largest sites of up to 13,800m² in just two days each and the smaller sites of 1,200-4,500m² in just a few hours after the schools were vacant in the evenings.
- By using BIM software we captured the geometric data of the rooms from the laser scan and then added the non-graphical data such as room name, number and ESFA block designation. This was scheduled from the model combining room areas and heights from the model.
Timescales and delivery
The workflow was tested to its limit with the first 5 schools which totalled over 50,000m². The smallest was just over 6,000m² and the largest over 13,000m² the site work was completed in under two weeks by a single operative with a mobile laser scanner. Data was captured in blocks of around 1,000-1,500m² and registered on site while the next block while the capture continued, allowing the data to be checked for gaps or errors and re-scanned if necessary before we left each site.
The relatively small file size of blocks of scan data allowed them to be sent back to the office nightly to be registered together. This meant modelling the rooms was completed in parallel for the large projects.
Using BIM to collate the spatial and non-graphical data meant that characteristics such as the ESFA Block designation could be visualised by colouring the rooms by attributes instead of manually applied fills.
Mobile laser scanning facts:
- Rapid internal capture ~6,000m²/day – equivalent station based laser scanning 1,200m²/day
- Suitable for Gross internal floor area (GIFA), facilities management, condition survey referencing and design feasibility.
- Accuracy equivalent to 1:100 scale