This study reviews the economic benefits analysis conducted in 2014 for the National Broadband Network (NBN), one of Australia's largest ever public infrastructure projects. The review identifies that the NBN's benefits were overstated due to error by an estimated $17–20 billion in 2014 present value terms, an amount sufficient to eliminate the NBN's forecast net economic benefits. To provide an updated view on the benefits of high-speed broadband in 2022, a stated choice experiment is conducted, finding that the WTP has grown since 2014 at an annual real rate of 8.8 percent for download speeds and 11.5 percent for upload speeds. Even at these growth rates, however, the benefits of the NBN remain materially lower than forecast in 2014. Further, the analysis finds high heterogeneity in the household WTP, with smaller and lower-income households reluctant to pay a premium for speeds much faster than 50 Mbps, indicating that the adoption of the fastest available broadband speeds is likely to remain low. The study highlights the potential value of cost-benefit analyses, but also the risks, particularly where they are relied on to justify enduring extensions of government ownership and control. The paper concludes by identifying learnings for policymakers and cost-benefit analysis practitioners seeking to assess and optimize the economic value of public infrastructure investments.

本研究回顾了 2014 年对国家宽带网络 (NBN) 进行的经济效益分析，该网络是澳大利亚有史以来最大的公共基础设施项目之一。审查发现，NBN 的效益因错误而被夸大，按 2014 年现值计算，估计有 17-200 亿美元，这一数额足以消除 NBN 预测的净经济效益。为了提供关于 2022 年高速宽带优势的最新观点，进行了一项规定的选择实验，结果发现自 2014 年以来 WTP 的下载速度和上传速度的年实际增长率分别为 8.8% 和 11.5%。然而，即使按照这样的增长率，NBN 的效益仍然大大低于 2014 年的预测。此外，分析发现家庭支付意愿存在高度异质性，规模较小和收入较低的家庭不愿意为比网络快得多的速度支付溢价。 50 Mbps，表明最快可用宽带速度的采用率可能仍然较低。该研究强调了成本效益分析的潜在价值，但也强调了风险，特别是在依赖成本效益分析来证明政府所有权和控制权持久扩展的合理性的情况下。本文最后总结了寻求评估和优化公共基础设施投资经济价值的政策制定者和成本效益分析从业者的经验教训。