Survey infrastructure preservation and upgrade: Trigonometrical stations in NSW

Land and Property Information (LPI) is the custodian of the geodetic infrastructure in New South Wales, which incorporates approximately 6,000 traditional trigonometric stations that formed the backbone of the survey control network before the introduction of more than 160 CORSnet-NSW stations. Keeping the ageing passive geodetic infrastructure current and ready for utilisation requires regular maintenance such as fit-for-purpose assessments, verification of owner records, contact details, access details, and (most importantly) recent, time-stamped Global Navigation Satellite System (GNSS) observations. As this level of maintenance is neither viable nor justifiable for the entire network of trig stations in the modern era, LPI has selected a subset of 'high-scoring' trig stations based upon a number of factors including a 'TrigStar' rating, monument quality and significance within the contexts of survey network, local community and heritage. After the successful completion of a campaign-style pilot project in the Central West, and subsequent campaigns on the South Coast, in Northern NSW and in Southern NSW, LPI continues to carry out this trig rationalisation and targeted upgrade across the State. LPI plans to complete its first pass of trig maintenance and upgrade before the realisation of the nation's next-generation datum in 2015. This paper outlines how this method provides an effective strategy to maintain geodetic infrastructure across NSW, connect traditional survey infrastructure with modern-day satellite-based positioning and contribute new GNSS observations towards the next-generation Australian datum.