Chipseal vs Hotmix

[Maha]

Generally speaking, the hotmix/asphalt type provides more grip than chipseal. Because of its lower noise, it is often used in higher speed zones adjacent to houses. It is almost always used on roundabouts, because it provides that better grip*, and lasts longer than chip seal. It does tend to get 'pushed' outwards into increasingly large humps (always on our line, of course).

* I have been told by roading people that there are different grades, offering a variety of skid resistance. Of course, the more expensive ones are better, so contractors often use the cheaper one/s despite Transit specs (and prolly charge the higher amount).

An intersting observation up thisa way John is, most of the stone chip road resealing does not last that long, maybe a year before it starts to flake away. They closed the brynderwyns a couple of weeks back for a day to reseal in Hotmix...went over them last weekend and all they have done is patch here and there, same with the Mangawhai road, surely it would more cost effective to get right the first time, or is it that, if they get it right there wont anything for them to do in a few years? Keeps them employed I guess.

[Maha]

No. To all of those.
Why are race tracks laid with some sort of hotmix/asphalt/bitumen? Quite simply, it is superior to chipseal.
It doesn't bleed cos it was never liquid. And it is less likely to ice up, because it is smoother and doesn't retain water (unlike chipseal, where water sits in all the hollows between the individual chips)

Hotmix doesn't bleed like chip seal does. It's much more resilient to temperature and lasts long.
As all ready stated it's all about contact patch. Both types need adequate drainage either way.
Gimme hotmix and lots of it.

Some days, this place is way better than school use to be!!!

[MSTRS:Me]

...surely it would more cost effective to get right the first time....

Like barriers?
These are quasi-govt departments we are talking about...'nuff said.

Some days, this place is way better than school use to be!!!

And just as pointless?

[nodrog:Me]

Some days, this place is way better than school use to be!!!

except you cant swap your sammies for some better ones

[Maha]

except you cant swap your sammies for some better ones

Hot Chip sammies?

[BOGAR]

grip is all about surface contact area, as long as there is no standing water hotmix will provide better traction than chipseal.

You could have a chip seal with polished stone giving the look of a good road surface (plenty of chip sticking up) but poor or very poor breaking characteristics.
AC is now mainly used because the process is less disruptive to traffic, quieter and the surface is less likely to fail under turning stress.
But reasons why it is used in one place and not another may just come down to the individual who is in charge.
The surface texture of a pavement-wearing surface is one of the primary contributors to tyre-pavement friction. Both macrotexture and microtexture affect the friction characteristics. As dose pavement smoothness and geometry.

[slofox]

...they'll sack alot of public service people...

Who will then go on the dole and use MORE money than has been saved...

[slofox]

Keeps them employed I guess.

You got it in one........!!

[Forest]

It's fairly well known that the coarse chip-seal used in the South Island wears down bike tyres quicker than other road surfaces.

Doesn't that meant that chip-seal has better grip?

[Pussy]

It's fairly well known that the coarse chip-seal used in the South Island wears down bike tyres quicker than other road surfaces.

Doesn't that meant that chip-seal has better grip?

No, it just means it's coarser and shreds your tyres!
I totally agree with the positive comments about hotmix/asphalt... superior grip in dry or wet, and no tar bleeding. I'd be happy to see every road surfaced in hotmix

[Forest]

No, it just means it's coarser and shreds your tyres!
I totally agree with the positive comments about hotmix/asphalt... superior grip in dry or wet, and no tar bleeding. I'd be happy to see every road surfaced in hotmix

I don't think that's right.

Chip-seal has a greater resistance to skidding in the wet because it has a higher level of grip than hotmix. Even the road-code acknowledges this:

http://www.ltsa.govt.nz/roadcode/abo...d-surface.html

[Pussy]

It is right. You don't see chip seal racetracks, do you? Far better grip with hotmix.... not to be confused with flushing tarseal

[R6_kid:Me]

What is the stuff on the Newmarket fly over? Seems to be a 'coarse' hot mix?

[Forest]

It is right. You don't see chip seal racetracks, do you? Far better grip with hotmix.... not to be confused with flushing tarseal

No. However you do see rather a lot of race-track crashes when it is wet.

I think chip-seal provides superior grip in wet conditions. If anyone has evidence to the contrary, please feel free to post it.

[Forest]

What is the stuff on the Newmarket fly over? Seems to be a 'coarse' hot mix?

I know the answer to this question!

The Newmarket viaduct is suffering from a really bad case of concrete cancer. So they've resurfaced it with a lighter coloured material (I think it is greywacke from the South Island) to prevent it from heating up during summer. That's why it has a different colour to the rest of the Auckland motorway system.

Within the next few years they will build a new viaduct beside the existing one, transfer traffic to the new viaduct, and tear down the old one (the old one doesn't meet the current regulations for seismic resistance).