KEY POINTS:
On State Highway 1 at Windy Ridge, north of Wenderholm Park, an electronic sign tells southbound motorists their speed. How accurate is this sign? It persistently reads about 7km/h below what my car's speedo says when I pass it. If this is incorrect, many motorists could be adjusting
their speed to what the sign is telling them, and inadvertently exceeding the posted speed limits.
A different sign on Grand Drive inOrewa warns northbound motorists when they are exceeding the 50km/h limit. I've set this off when not too much above 50km/h. I appreciate the reminder and warning to keep my speed down, but now I'm wondering.
Which sign is most likely to be correct? Do the appropriate authorities know that one sign is likely to be inaccurate?
Wendy Howard, Kaiwaka.
The sign at Windy Ridge is a 3M product, and the company's traffic systems division thanks you for keeping them informed. They've been out and checked the sign, and they've also had the police use their calibrated onboard system. They found that the posted reading was consistent and accurate to the 1-2km/h that they expect.
The Grand Drive sign in Orewa is not 3M's, but it thinks the radar would be set to flash the 50km/h sign when a vehicle is approaching at a pre-determined speed above 50 to encourage it to slow down. 3M also says that it can be difficult for drivers to self-check their speedo reading against the sign with any great accuracy. Also, it is common for the typical family sedan to have a higher speedo reading than the travelling speed.
And in a similar vein -
Increasingly one sees illuminated speed signs on the side of the road. I noticed that if I go past one while doing less than 50km/h, the sign will read, say, "Your speed 48."
But if I go faster then the sign alternates between "Your speed SLOW" and "Your speed DOWN". Both messages encourage me to go faster. What is the purpose of these signs? Is it to speed up traffic? Have any studies been done regarding their effect?
Tony Cooper, Mt Albert.
As can be seen from the picture, the "Your speed" part of the sign is fixed. It's the electronic part that alternates between "Slow" and "Down" when you go past at too high a speed.
The purpose of the signs, then, is to encourage traffic to slow down. They have been effective overseas, which is why they were introduced here.
What are the rules about people using pedestrian crossings? Years ago, you were taught to stop at the edge of a crossing and look both ways and not step out on to the crossing if a car was within the diamonds painted on the road. Today people seem to walk straight out on to a crossing no matter how close a vehicle is. Have the rules changed?
Michelle de Brouwer, South Auckland.
The rules haven't changed substantially, although there has been some differentiation made between crossings that have an island in the middle and those that don't.
The Road Code says pedestrians should not step out suddenly on to a crossing if a vehicle is so close to the crossing that it cannot stop.
It also states that drivers should be ready to stop near pedestrian crossings. It's a case of always lookingout for other road users, and having a duty of care, and that applies to everyone.
