KNOW HOW / EXPLAINER
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einforced aerated autoclaved concrete (RAAC) has been found in more than 50 hospitals, 200 schools and many other public and private buildings. With an intended lifespan of 30 years, the material has long outlived its use in many locations. One of the main problems with RAAC is its vulnerability to moisture, which can weaken it and lead to collapse. Airedale General Hospital has one of the highest quantities of RAAC panels in the NHS, with 83% of the hospital’s floors, walls and ceilings made of the material. Built in the late 1960s, the hospital in West Yorkshire discovered its RAAC problem five years ago and is due to be rebuilt by 2030, as part of the government’s New Hospital Programme. Having used a manual, hand-written survey process to monitor RAAC until 2023, it was clear this was insufficient to deal with the volume of work. The hospital required a more sophisticated method of tracking defects and monitoring how different sections of the planks were deteriorating at different rates. What was needed was a single, joined-up view of RAAC
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BU ILDING S AFETY
Detecting and tracking RAAC Indoor mapping is helping to advance the management of reinforced aerated autoclaved concrete, says Richard Burgin risk to generate the inspection frequencies and inform the ongoing programme of remediation works.
The technology deployed
BIS Consult was appointed by the hospital to implement a new RAAC data management solution. Using Esri UK’s GIS (Geographic Information System) software, the team created a system to replace paper-based processes with digital workflows to improve the accuracy and efficiency of RAAC inspections. Esri GIS provides digital maps, apps, dashboards and tools to analyse spatial data. At Airedale, it has been used to map indoors of the hospital to reveal where the highest risk areas are in real-time, which informs the mitigation works, including temporary propping, steel reinforcements and fixing
FAC I L I TAT E J U LY-AU G U S T 2024
which planks to inspect. Improved insights are generated faster than before, as the GIS can run different spatial analysis and scenarios, including tracking monthly changes in residual risk and providing detailed information relating to each specific concrete plank. Patterns of deterioration can be clearly seen and investigated on an estate map, overlaid with drone imagery, which helps stakeholders understand the problem more easily. Factors that impact upon RAAC, such as the location of utilities and services, the orientation of a building and prevailing weather, can be better assessed using this method.
The results
The digital approach has created a more resilient roof leaks, to maintain the safe process, with a reduced risk of operation of the hospital. human error, and renders the RAAC has a major information on RAAC more operational impact, sometimes shareable. This improves the disturbing clinical and ability to communicate the operational functions so scale and complexity of the surveys and mitigation work problem with internal and needs to be accurate and fast – external stakeholders. and the system underpins that. In terms of cost savings and return on investment, The way it is deployed the system pays for itself; the Inspection data is now process of inspections is 50% collected on iPads using more efficient and has saved custom forms, which helps recruiting four additional fulldictate the risk rating of each time surveying staff. plank. This data feeds Overall, the GIS back into the central is a powerful tool mapping application. that helps manage Planks are surveyed the sheer volume monthly, quarterly, of work, provides bi-annually or yearly, a single source of depending on their truth on RAAC risk RICHARD BURGIN is rating, in line with and helps prioritise estates project current guidance. The where interventions manager output instructs the are required to at Airedale survey team which keep the hospital General wards to survey and Hospital running safely.