I was looking for clarification as to whether there is a law when it comes to speed restriction signs that they must be placed / repeated a certain distance so you know that you're still in that restricted zone, and if they're not the restriction becomes invalid? Two scenario's I have come up against a few times: 1) Road works where you have to slow to 40/25kph. However the workers have not erected any sign the other end saying that you can speed back up to 100/110kph. (Or they pulled down one side for the weekend and forgot the other side, etc). I was wondering at what point/distance does the last 40/25kph zone become invalid, or technically am I expected to continue at the last posted speed limit for the next 75km's until I reach the next town / sign? 2) Normal speed zones. I have ridden in areas that slow to 60kph. Take a turn, and it eventually leads back out onto a rural area - but again there is no sign to say you're back in a 100/110 zone. If coming the other way I would assume that the 50kph for 'built up' areas apply if not otherwise signed, but at what stage can I legally speed to 100/110kph when there are no signs down those roads saying I can... ever.