
Originally Posted by
Motu
The randomness and variable quality of the spray with tar and toss on some chip repair puzzles me....response from the guy who knows is welcome.This is a Private Investigation,Not a Public Inquirey.3 I have noticed recently -
Following comments in the interests of providing some technical info only - had enough of the politics. Tar is what they use to use till the coal gas plants were closed, now days it is bitumen, which is a heavy component of oil (butane is a light component of oil). Bitument was originally promoted by shell as they had excessive amounts of it liying around and they wanted to find a market. Bitumen is better than tar in that it is a more consistant product.

Originally Posted by
Motu
Mahia Rd in Sth Auck was done a few months ago,it has mostly come off leaving a hell of a mess,WTF? Why even bother? In Mt Roskill Dornwell Rd and Britten Ave were rechipped - while they were doing it someone dug a trench across the road,they worked around it and the trench was filled with hot mix,while they were still doing the chip!!!! Like...like,oh,I just give up.There is still loose chip because they can't sweep with all the parked cars.Why don't they just close the road,do the job,and finish it....too much PC crap in their way.
Most city council standards now requre that any road opening (trench) be surfaced with mix. This is bacause of a number of reason as I understand it
1 - Easier for most contractors to turn up with a bit of mix on a truck than to heat and transport bitumen to site.
2 - High traffic volumes (anywhere in town) generally ruin chip seal before it gets a chance to go off i.e. bitument cool and thinners (desiel/kero) evaporate. This is especially true in turning and accelleration/braking areas including parking areas (even on street parking). Mix is much more durable in a much shorter period.
In saying all of this it is pretty crappy (looks shit if nothing else) to put a mix patch in a brand new seal - especially when seal is being laid at the same time. Some engineer who signed off onthe road open notice should have spotted the overlap of works at the site and adjusted reqirements.
Sweep can sometimes be posponed due to point 2 above. The excess chip protects the seal/bitume while the bitumen is going off. Would have expected that a week should be sufficient though. Any longer than this is lazyness on contractors behalf and poor management for not following through. Also chip seals weill continue to loose chip for quite a long time afterwards (could be a year depending on traffic). This is because often loose chips get caught betwen others and are not swept up but as the stuck chips settle due to traffic the loose chips can become properly loose and flicked out. There can be a supprising amount of this depending on heat of day, how little or much traffic there is and the type of chip seal.

Originally Posted by
Motu
The entry and exit of the Rangiriri bridge were done a few days ago - I knew that because the road had paint marks and bad spots marked.There is a hump pushed up in the middle of the corner on the west side,by the Te Kauwhata Transport trucks.It's in the centre of the road and in no ones way...unless you cut the corner or run wide....and it was marked with yellow paint,that's good I thought.So they have rechipped....and the hump is still there,they just tarred and feathered right over the top!
Trucks turning into yard possibly rolling chip (stones can be turned in bitumen) hence bringing bitument to top (called bleeding). This is a skidding hazard and also causes a mess (ever played in hot bitumen). Old fasion practice is to burn the bitumen off but this produces massive clouds of icky smoke. Now days either waterblast and suck up crap or seal over again with reduced quantities of bitumen to try and stop bleeding. As for hump - chip seal does nothing to smooth a road - that requires diging the lump out and there may be good reason for it being there such as making sure there is the minimum cover over a buried pipe. This is to ensure the loadings on the pipe are not to high as aggregate over a pipe distributeds the load (there is a maximum cover for pipes as well but that is usually 10's of metres deep).
Hope this is informative.
Cheers
R
Last edited by cooneyr; 7th December 2006 at 13:32.
Reason: Added point about chip loss
"The ultimate result of shielding men from the effects of folly is to fill the world with fools." - Herbert Spencer, English Philosopher (1820-1903)
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