A coastal lighthouse's warning signal is often referred to as a public good. This is because:
all lighthouses are financed and constructed by private shipping companies
lighthouses are the most visible safety features along a national coastline
the consumption of the warning beam is non-rivalrous
there are external benefits generated during the construction of lighthouses
24 exam-style questions on Edexcel A A Level Economics 1.3.3 Public goods. Each one has a worked solution and a mark scheme showing where the marks go.