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How we make your roads

Discussion in 'Roads, Touring, Journeys, and Travel' at netrider.net.au started by _joel_, May 19, 2007.

  1. It occurred to me that there is generally little knowledge of the construction of the most common road surface in Australia.
    when people shoot me questions, it is always about "TAR", "Laying", etc.

    this is more than likely because you poor buggers are stuck in a line of traffic whilst the actual work is being carried out, just like this.....

    HAHA, you goin' nowhere :p

    While you are waiting, a highly dangerous set of events is occurring in front of you.
    The binder (or base binder) used in australia and the world for making roads is no longer TAR. We use manufactured and refined Bitumen which is basically the leftovers in the oil/fuel refinery process.
    whilst bitumen is similar in appearance to tar, it is not tar. and that is important as tar is a known carcinogen.
    for the record, Tar is made from the distillation of organic matter, and for roading, mainly wood/pine.

    now that we have that sorted, we use bitumen which is sprayed at a designed rate of L/m2 and then covered with a designed and graded size of aggregate. This is then Rolled in to the surface, and then left for the traffic to do its job of rolling it in further before it is swept clean.
    what you have after all this is a lovely, high skid-resistant road surface.

    now for some pictures-

    Road Base, formed prior to seal.

    this is a good example of a well prepared road base. nice crown, tightly bonded and ready to seal.

    Sprayer truck, starting the "run" spraying bitumen via its continental bars at a rate (for this design) of 1.2L/m2 and a width of 3.5m (one lane).
    this is the dangerous part, the bitumen is around 200c and under plenty of pressure. if something fails here, like a bar-gasket, it will spray 15-20m in any direction. at 200c it burns, and burns quick. this is why we make you stop, and you dont get very close to the action.
    Note- directly behind the sprayer is a tipper truck, with a load of 14mm aggregate ready to begin the spreading process. the sooner the aggregate gets on, the better it sticks.

    The same sprayer, from behind as it goes past
    the smog behind the truck is nearly 100% steam. a small portion of this would be kerosene fumes.

    This is the spreader truck, applying the aggregate to the freshly sprayed bitumen. the aggregate is spread at a controlled rate, which is maintained by the dude walking next to it holding a small remote control. The aggregate trucks used to be hand operated, but it is a quick way to get dead should you come in to contact with an overhead wire.
    in this design, those rocks are going down at a coverage of 100m2/m3, and there is only an allowance of 5% for error :shock:

    This is more or less the last part of what we do, other than the post-sweep. the aggregate is rolled in to the base by the roller. this particular roller has a rubber drum that vibrates and multi-tyres at the rear. specs require that each stone has 8 passes of the roller.

    this particular job was a 2 coat seal. first layer is 14mm aggregate, second being 7mm aggregate. both layers get a coat of bitumen, and both are rolled.
    this job was about 1km long, and took around 2hrs to complete.

    any questions???

    \m/ rock on, and thanks for listening :grin:
    • Like Like x 5
  2. And 'what was i doing while all this was going on' i hear you ask?!

    sitting in here-
    taking pictures :p
    usually, i would be sitting in there either on the phone, UHF, or crazily using the calculator to make 24500L of bitumen fit in to 14000L worth of onsite storage :LOL:
  3. a truely original post and an interesting read at that!!

    8 apples out of ten.
  4. thanks!
    with any luck, more of us young folk will become involved in spray-sealing. whilst the design methods and principles are still in their infancy world-wide, Australia and New Zealand are leading the way to perfecting the processes.
    there is big $$ in this industry, entry level traffic controller gets 60k+ and a stupidvisor like me gets a package around a ton.
    i strongly urge anybody that has a civil engineering or similar background to enter the industry.
    • Agree Agree x 1
  5. Wow, what a fantastic post :D I'm a big sucker for sitting back and watching what other peoples jobs are about and that rundown is kickass :)

    Question from my gf: how do you fill potholes? :)
  6. Joel,

    Thanks very much for the informative post. I never really knew how it was done....

    Two questions though;

    1. If the bitumen laying process could be so explosive, how come the workers are allowed to stand so close to it without any protective clothing (i.e. faces)

    2. Are you saying that the person holding the lollipop stick earns about $60k pa
  7. thanx joel, stump loves a bit knowledge. [hmmm good idea for a thread]
  8. What a fangatastic post Joel

    was very informative and interesting

    I want to know also if the loolypop holder earns $60K
    if so I could handle saying goodbye to Medicare :p
  9. Would be good if the loose gravel often left behind was well swept, as in lots of cases it isn't.
  10. Thanks for the info dude :)
  11. I also get to spend lots of time sitting in my ute at road works, thing is I dont work at them so I dont get $60k a year to do it
  12. we pretty much dont fill potholes, that is the individual councils responsibility. but if we had to fix them, we would use a product called PreMix (cold mix asphalt) that we make back at the plant. it is a mixture similar to concrete, but using bitumen as the binder, and plenty of kero/diesel to keep is pliable for long enough so that it doesnt 'go off' in the ute/truck. it is a far better option than the council jetpatcher which just provides a porous chunk of road that effectively seals nothing :)

    1.bitumen is extremely dangerous and there are rules as to what PPE is required when working around the back of the sprayer truck. i know it doesnt look like it, but those workers are all at least 3m from the continental bars. that is the rule, 3m for workers who have completed the "Working Safely with Bitumen" course and 5m for the general public.
    these exclusion zones are not fantastic, as at a recent incident i measured the distance that the bitumen squirted, and 3m isnt enough. but thats another story.
    for a worker inside the exclusion zone, it is required that overalls, workboots (elastic side) helmet w/ faceshield, welders style gloves, hood/balaclava be worn.
    2. yes, that is why he is smiling ;)

    there are specifications as to how many loose particles can be left on the road after we leave the job, and that is prior to final post sweep.
    a rural road with traffic count of 250 vehicles per lane per day can have no more than 30 loose particles per square metre. if you go out to any road, you are going to get a count of around 5-10.
    some companies live by the seat of their pants, chucking a coupla signs up and hoping the stones settle down with traffic.
    bad idea
    its these mobs that we (AAPA) are trying to educate.
    if you come across a road that has shit all over it, call the council and report it. they should have a suction broom there asap because it is dangerous.
    the other time that you get loose stones is when a seal starts to fail, ie stripping. this is when the designed binder application rate was too little to effectively hold the aggregate to the road. this can take 6-12 months to start to show through, and with something like a 14mm reseal it can be very dagerous.
  13. Thanks for that joel very interesting.

    Q. The aggregate truck, the guy at the back controls the flow rate of the aggregate out from the truck, yeh? What controls the speed of the truck itself? I mean is the driver in the cab driving in reverse using the tacho for regulating his speed?
  14. truck speed is controlled by the driver, and is to be kept steady. however should he speed up or slow down, the spreader dude can open or close the flow gate accordingly to compensate.
    when they are first learning, i am sure they look at the tacho, but with experience comes the ability to feel how fast you are going.
    not only is the driver reversing, and watching where he is going, he is also controlling the hoist (it makes the tipper body go up and down) which is quite a complex art to master.
    these guys are extremely skilled operators and do more kms in reverse than you and i do in forwards :LOL:
    on the back of the tipper you will notice a speaker/mic setup. this enables direct communication between the driver and the spreader, so if the truck needs to go faster, you simply say so etc.
    these comms are important when you get in to town, because of overhead lines, you tell them to go up or down accordingly.
    you could use a handheld uhf, but because there is 3 or 4 tippers backing down the job at the same time, it would get confusing as to who was talking to who.
  15. That was interesting! As a child I remember being completely fascinated by the process, but most of all by the smell... but nowadays it no longer holds the same attraction. Maybe because the smell I remember is that of proper tar not this rubbish bitumen stuff?

    But even if it doesn't smell so sweet any more, I'm still interested in $$... seriously, what are the entry paths to this line of work? I used to wield a mean lollipop as a child, does that count? :)
  16. Go back, you missed a bit! :LOL:
    I'd go into road works, but I don't want to be tarred with the same brush! :rofl:
    Actually, I had an interview with a road making company, but they wouldn't give me anything concrete! :rofl:
    Seriously, if it wasn't for teh travel all over the place, it's teh sort of work I'd like to do.

    Regards, Andrew.
  17. Joel, since you are the man when it comes to this, even though I'm not in NSW, I wanna be a lollypop dude, have for ages, not just the money, but also coz I'M NOT STUCK AT A FREAKING DESK TALKING TO MORONS ALL DAY.

    I know people, so I can get the job easily.

    Tell me about the job. I was told I need a traffic management certificate or something...
  18. for a job as a traffic controller you need to do the Traffic Management course. We have an internal training system, and this is one course that EVERYONE needs to have.
    this makes you an authorized traffic controller.
    the job isnt the best though, people in traffic lines are abusive, arrogant, and are always late for work/doctor/got ice cream in the boot :roll: i have heard it all. it isnt as easy as it looks either, standing for a periods of time, without moving gives me a sore back, and then you have the issue of people ttrying to run you over because they dont need to obey roadwork speed limits because they cant see anything dangerous. also, there is the guy who drives straight past your stop sign...and upon questioning, he tells you that you had no signs up :roll: even though if he was to drive with his eyes open :shock: he would have seen the 12-20 signs over 1.5kms from where you are standing.
    people are tedious and annoying, and the traffic controller is the interface between us and them. anyone who honestly thinks that a lollipop man is slow, or lazy, or whatever else i used to think before i worked in this environment needs to come and have a go :) i need 100% trust in my traffic controllers, because it is my job to deliver my boys home as alive and healthy as they were when they left, and traffic is a far more dangerous hazard in roadworks than any exploding bitumen incident ;)
  19. Cool.

    You haven't scared me away!!! I just want to be outside or work at the opposite end of the day!

    Plan A was to be a sparky, but being over 21 & a girl is working against me :(
  20. i definitely encourage girls to do it! :grin: