The National CORS Network and Surveying Productivity in Vietnam: A Techno-Economic Assessment of VNGEONET

Vietnam completed its national satellite positioning network, VNGEONET, at the end of 2019, and in September 2024 moved the service from free trial access to a priced public utility. Both steps were justified on productivity grounds, yet no published study has quantified how much surveying productivity the network can plausibly deliver, or under what conditions the new access charges leave users better off. This paper builds a transparent techno-economic model to answer those questions. Network geometry is assessed against the tessellation implied by the published station spacing; workflow effort is decomposed into mobilisation, control establishment, detail observation and office processing; and the resulting crew-hour requirements are compared across three technology configurations under two counterfactuals, a fully conventional workflow and single-base real-time kinematic surveying. Parameters are declared explicitly and stress-tested through a grid of break-even calculations, a 200,000-draw Monte Carlo simulation and a tornado analysis. Four findings stand out. The forty-one network-RTK stations cover between 26.8 and 68.6 per cent of the national land area depending on the spacing assumed, so the binding constraint on realised productivity is geographic rather than financial. The annual access charge of 6,750,000 VND per receiver is recovered after roughly twenty-three field-days against the single-base counterfactual and about five against the conventional one, and avoiding the purchase of a base receiver is worth several times the annual fee on its own. Crew reorganisation, not correction quality, determines whether the investment pays. Finally, the statutory labour norms consolidated in 2025 price photo control identically whether performed by total station or by GNSS, despite a 4.88-fold difference in the equipment norm, and establish no norm for real-time kinematic methods at all, so the productivity quantified here is invisible in the settlement of publicly funded work. Pricing reform is therefore second-order next to densification and norm revision, and the absence of published adoption statistics remains the main obstacle to evaluating the investment.