Sorry there was small rounding error, the cost is now HK$580B..
Another small rounding error, the revenue from land sales is cut by HK$400B (only)..The studies are part of the Lantau Tomorrow Vision, an ambitious undertaking announced by Hong Kong Chief Executive Carrie Lam in 2018 that is estimated to cost up to HK$500 billion.
https://www.thestandard.com.hk/secti...ion/11/248427/Land sales revenue was estimated to reach up to HK$1.14 trillion by the Hong Kong Institute of Surveyors in February 2019, but that has now been adjusted to HK$750 billion.