Fifteen years ago, the South Australian State government proposed a high speed expressway; it was going to cost a lot, but it was going to greatly reduce travel time between the city and the Southern suburbs.
It did, for 5 years. Then a girl failed to check her blind spot, side-swiped a truck and died.
Within a month a huge chunk of the city end had been reduced from 100kph to 80kph and even 70kph, and it'll only go down from there.
We're all still paying full price, of course.

... and where do you think the cops set up their speed traps?