What is our road made of?

[Ixion]

I guess you need to consider there are many road users, from small 50cc mopeds, to 40T trucks.

There are also competing needs. Grip, road noise, tyre wear, durability.

Its probably difficult to find a road surface good for everything. So they probably aim to satisfy as many people as they can.

On the whole, I would have to save I'm happy with the standard of seal around Auckland.

No, it's not hard. In fact , some roads already have such a surface. Buried UNDER the tar seal! Concrete. We used to build roads out of it.

It doesn't melt. Ever. It has consistent grip . It is completely resistent to breaking up even with 50 tonne trucks, For like, the better part of a century.

If you live in Auckland, next time they are resurfacing one of the old main highways (Ellerslie Highway, Mt Wellington Highway, Great xxx Rd, Onewa Road, others) take a look. Under six inches or so of tar you will find concrete. The top is usually a mess now, it's been scabbled to provide a grip for the tar. But it's been down there , getting pounded , for 70 or 80 years maybe. And odds are it'll STILL be in good nick.

In the USA, it's what they use for Interstate highways.

Why don't we use. Cos we're cheap. And only interested in the short term cost.

[p.dath]

I've done some reading about the creation and standard of hot mix. All I can say this is a very complex subject. We may think it is easy to build a better road, but it is very much a science - and the needs can vary from road to road. The "formula" for one area may not suit another

As an example, a twisty road may need a mix with much greater torsional strength, but a side effect may be a much noiser road.

The standard used in NZ seems to be mostly controlled by the NZTA:
http://www.nzta.govt.nz/resources/ch...alt/index.html

Many different countries use different systems, different mixes, and have trialled different experiments. Any guess what, lots of other motorists from other countries aren't completely happy with what they have either.

I've updated the Wiki article about NZ roads with some of the info I have found:
http://www.kiwibiker.co.nz/wiki/New_Zealand_Roads
Please feel free to augment it with more info.

I can concur with Ixion, in that concrete seems to be well accepted, but it seems few countries used it for the majority of their roading because of the huge expense.


So I guess a lot of it comes down to the roading engineer who decides which hot-mix formula will deliver the best results within the budget available. And I guess sometimes they don't get it right everytime.

[p.dath]

Another interesting snippit on roading:
http://en.wikipedia.org/wiki/Pavemen...ment_.28BST.29

As pavement systems primarily fail due to fatigue (in a manner similar to metals), the damage done to pavement increases with the fourth power of the axle load of the vehicles traveling on it. Civil Engineers consider truck axle load, current and projected truck traffic volume, supporting soil properties (can be measured using the CBR) and sub-grade drainage in design. Passenger cars are considered to have no practical effect on a pavement's service life, from a fatigue perspective.

Other pavement failure modes include ageing and surface abrasion. As years go by, the binder in a bituminous wearing course gets stiffer and less flexible. When it gets "old" enough, the surface will start losing aggregates, and macrotexture depth increases dramatically. If no maintenance action is done quickly on the wearing course (seal coating, surface dressing, etc.), potholing will take place. In areas with cold climate, studded tires may be allowed on passenger cars. In Sweden and Finland, studded passenger car tires account for a very large share of pavement rutting.

Several pavement design methods have been developed to determine the thickness and composition of pavement required to carry predicted traffic loads for a given period of time. Pavement design methods are continuously evolving. Among these are the Shell Pavement design method, and the American Association of State Highway and Transportation Officials (AASHTO) 1993 "Guide for Design of Pavement Structures". A new mechanistic-empirical design guide has been under development by NCHRP (Called Superpave Technology) since 1998. A new design guide called Mechanistic Empirical Pavement Design Guide (MEPDG) was developed and is about to be adopted by AASHTO.

According to the AASHO Road Test, heavily loaded trucks can do more than 10,000 times the damage done by a normal passenger car. Tax rates for trucks are higher than those for cars in most countries for this reason, though they are not levied in proportion to the damage done.[9]

The physical properties of a stretch of pavement can be tested using a falling weight deflectometer.

[steve_t]

Another interesting snippit on roading:

...heavily loaded trucks can do more than 10,000 times the damage done by a normal passenger car.

Geez!! All the more reason to give bikers a break

[Mikkel]

Ok, this is how the system works.
Auckland council civil engineers are given the task of building some infrastructure. The actual construction (including roads) comes under contract and the contract goes up for tender.
The big fish, (fulton hogan, works infrastructure etc..) make applications with the dollar figure they think they can complete the contract in.
WHOEVER APPLIES WITH THE LOWEST FIGURE, GETS THE JOB.
With having progress deadlines and penalties etc... the job is done at the lowest cost.

Yes, that is how litigation works. However, it is not the fault of the contractors that the specifications are set too low. The problem lies in not being willing to require high enough specifications, mainly because doing so would make the road more expensive.

No, it's not hard. In fact , some roads already have such a surface. Buried UNDER the tar seal! Concrete. We used to build roads out of it.

It doesn't melt. Ever. It has consistent grip . It is completely resistent to breaking up even with 50 tonne trucks, For like, the better part of a century.

I was under the impression that concrete provides poor traction in the wet and that the ride comfort suffers (maybe not compared to rough chipseal...). Or are you talking about an asphalt/concrete mix of some sort? Asphalt is what the roads are made from back home, various kinds too depending upon the specific location - i.e. surface with low roughness in residential areas to reduce road noise and surfaces with higher roughness on secondary roads in the rural area where snow clearing doesn't happen so quickly.

The old autobahn sections made from concrete have rather annoying gaps between the concrete elements, that doesn't make for a comfortable journey.

[Motu]

No, it's not hard. In fact , some roads already have such a surface. Buried UNDER the tar seal! Concrete. We used to build roads out of it.
If you live in Auckland, next time they are resurfacing one of the old main highways (Ellerslie Highway, Mt Wellington Highway, Great xxx Rd, Onewa Road, others) take a look. Under six inches or so of tar you will find concrete.
.

I thought the Yanks did those? Or has my hero worship gone too far? But there are too many concrete roads for them to have done them all....maybe just Panmure/Ellersllie and Mt Wellington Highway....to get stuff to Camp Bunn and Sylvia Park? We should have let them dig the canal,before anyone could say no.Anyway - I never ever saw damage to to concrete roads,they were permanent,like forever.Sure,I spun out of control a few times,cars and bikes....but never on a concrete road.

[jasonzc]

Not trying to insult anyone or offend anyone at all..

I completely agree that the govt are trying to be 'cost effective' ie cheap..

but if another increase in levies or taxes to pay for better road/maintenace etc, then im sure we will be on here again complaining bout that.

Though the govt still could be more efficient with its spenditure

[MSTRS:Me]

but if another increase in levies or taxes to pay for better road/maintenace etc, then im sure we will be on here again complaining bout that.

Since when has our government ever introduced (or raised) a tax for (any specific purpose) and then actually used the money for that purpose?

[yungatart]

Not trying to insult anyone or offend anyone at all..

I completely agree that the govt are trying to be 'cost effective' ie cheap..

but if another increase in levies or taxes to pay for better road/maintenace etc, then im sure we will be on here again complaining bout that.

Though the govt still could be more efficient with its spenditure

It doesn't have to be paid for out by raising taxes. Theoretically, if we built better quality roads, they would need less maintenance dollars being spent on them and would last considerably longer (as in years). They could be funded out of loans and paid back in the future by future taxpayers who would still be deriving the benefit of using a higher cost, better quality, longer lasting road.

[davebullet]

Problem is drivers don't keep their eyes on the road. Therefore make the road out of superglue and naked virgins. (Problem is NZ is running out of the latter).

[Mudfart]

If anyone has a problem with NZ roads, don't EVER EVER go to the UK.

[red mermaid]

I've never been to the UK, but have been to Australia.

I found the interstate roads to be of a much higher quality than the State Highway roads in NZ.

However the rest of the roads seem to be about the same as we get here.

[Hans]

It'll get worse when bigger trucks hit our roads.

Please elaborate? Bigger trucks?

[red mermaid]

The maximum gross weight currently allowed is 44 tonne.

Trials are being held on 50 tonne units, and the Road Transport Forum is lobbying hard to bring them in nationally.

[Hans]

Aaaaah. HEAVIER trucks. Now that I already knew about, being a truckie myself. Hate being a cynical Katman, but I guess I'm in that sort of mood today...