The Reason For Road Signs

**Slim** · 13th February 2004, 13:25

I have finally figured out what relation to anything the speeds on these signs have. They've certainly got nothing to do with road or weather conditions.

They're the speed that SUV's/4-wheel vehicles can safely get around the corner.

**Big Dog** · 13th February 2004, 13:29

Originally Posted by Slim

They're the speed that SUV's/4-wheel vehicles can safely get around the corner.

Lowest common denominator.....................

and unsafe driving geometry.

**Hitcher** · 13th February 2004, 14:04

In many cases I reckon you can safely add 40% to the speed indicated on the sign (on a bike, in the dry). But occasionally you find one that is absolutely spot on! I reckon they're calibrated using the "egg-in-spoon" gravitometer.

**Big Dog** · 13th February 2004, 14:11

Originally Posted by Hitcher

In many cases I reckon you can safely add 40% to the speed indicated on the sign (on a bike, in the dry). But occasionally you find one that is absolutely spot on! I reckon they're calibrated using the "egg-in-spoon" gravitometer.

Apparently they are decided by the speed that somone who has never been around that corner could safely take it in the worst likely road conditions, in the worst likely vehicle. I'm guessing this is done using the old sheepskin scale. Try it a few times at slightly slower speeds until you stop sucking up sheepskin.

I really laugh when they lower the speed limit but leave these signs up.

In Egmont Village in NP the 50 kmph zone was extended to include the bridge and the first corner but the corner was posted at 85. It would have made a great photo.

**Motu** · 13th February 2004, 14:16

Coming down the Southern Motorway last night just past the Manukau interchange there were two 4x4 thingies locked together pointing north,looks like one had been off road,tyres ripped off rims etc.....how the hell can that sort of thing happen on a fairly straight peice of road with all traffic moving in the same direction at roughly the same speed? I get the feeling that 95% of the people in cars around me are a gnats dick away from disaster.Glad I wasn't on a bike close by when those two bulls locked horns.

**Zed** · 13th February 2004, 14:17

Originally Posted by Hitcher

In many cases I reckon you can safely add 40% to the speed indicated on the sign (on a bike, in the dry). But occasionally you find one that is absolutely spot on! I reckon they're calibrated using the "egg-in-spoon" gravitometer.

You can definately take a 65km bend at a higher speed...it's the 35-45km ones you need to take notice of cos some of them are hairpins!

Those signs are definately beneficial to a rider when he/she isn't familiar with the road...but once you get to know that road- yeeha!

Zed

**What?** · 15th February 2004, 19:33

Originally Posted by Hitcher

In many cases I reckon you can safely add 40% to the speed indicated on the sign (on a bike, in the dry). But occasionally you find one that is absolutely spot on! I reckon they're calibrated using the "egg-in-spoon" gravitometer.

Or double it and add GST. But these signs are a good advisory on unfamiliar roads - especially if you drive a truck...

**Milky** · 15th February 2004, 19:59

i usually convert to mph in my head and base my speed on that... unless, as zed says it indicates a slow corner ie 25-35 then i slow down a bit more, possibly to plus 30% (for me little 125 anyway)
All this assumes that the roads are in reasonable condition ie dry/no leaf litter/oil/all those other nasty things on the road

**marty** · 15th February 2004, 20:00

i always thought it was how fast you could ride around them in MPH

**MikeL** · 15th February 2004, 20:20

Can anyone explain why the overwhelming majority of advisory speed limit signs end in -5 not -0? Apart from the occasional 20 or 30, almost always they are 45, 55, 65, 75 etc. Is there a reason for this that is so obvious that I'm the only one who can't see it??

**Two Smoker** · 15th February 2004, 20:21

I use milky's rule too, MPH is the speed u go at round the corner unless u hav a bad feeling about it, But becareful of the odd bastard tht does really mean tht speed (ie Senic Drive in the Waitaks where they resealed the cornerswith chip seal and forget to brush of the excess on the 35kmh corners

)

**Two Smoker** · 15th February 2004, 20:24

Originally Posted by MikeL

Can anyone explain why the overwhelming majority of advisory speed limit signs end in -5 not -0? Apart from the occasional 20 or 30, almost always they are 45, 55, 65, 75 etc. Is there a reason for this that is so obvious that I'm the only one who can't see it??

Its probably policy, this dueing to the fact the Speed Signs are always given with even numbers (30, 50, 60kmh etc) therefore the Speed ADVISORY signs are given odd numbers (25, 35, 65kmh etc) so they are not confused for Speed signs.

**Zed** · 15th February 2004, 21:02

Originally Posted by marty

i always thought it was how fast you could ride around them in MPH

That's just not logical marty! All speed signs in NZ are in kms.

These signs are not indicating a legal speed limit but rather a suggested safe and comfortable speed for the curve.

Zed

LB · 16th February 2004, 05:00

Originally Posted by MikeL

Can anyone explain why the overwhelming majority of advisory speed limit signs end in -5 not -0? Apart from the occasional 20 or 30, almost always they are 45, 55, 65, 75 etc. Is there a reason for this that is so obvious that I'm the only one who can't see it??

yeah, I'd wondered this too!