From the Sydney Opera House to a basic kitchen renovation there are thousands of examples of construction projects large and small which go horribly over budget.

Professor Bent Flyvbjerg has compiled a database of 16,000 projects, and by his reckoning only 8.5% them meet their initial estimates of cost and time. He talks to Sam Fenwick about his new book, “How Big Things Get Done”.

Presenter / producer: Sam Fenwick Image: Sydney opera house; Credit: Getty Images