mtb345
Well-Known Member
on the gps blade control system when grading a parking lot or a road do you still need a grader to tighten things up before paving ?
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gps dozers
- Thread starter mtb345
- Start date
JimBruce42
Senior Member
I'd say not likely, of course, you could also just put the GPS on the grader too, and not have to worry about back dragging your grouser marks out. A big parking lot, you'd probably just have the dozer push out the piles and keep them within +/-0.2' and still want to use a grader to finish grade it.
I'm not expert on dozer or grader, but from my short time on both I have to say it is a lot easier to hold a grade with a grader than a dozer, course I could just be weird
:beatsme
I'm not expert on dozer or grader, but from my short time on both I have to say it is a lot easier to hold a grade with a grader than a dozer, course I could just be weird
:beatsme
Squizzy246B
Administrator
Aren't you talking about laser level control system...GPS is a whole different ball game??...and not very accurate for height/Grade.
I usually can get it to within .05' with the GPS dozer. You're not going to get it perfect with the cleat marks anyway. And it seems like I always have a little windrow that comes around the corner of the blade if I take anymore than half a pass. If I have a grader available I'll rub it once just to pretty it up but if not the smooth drum roller will do just fine.
I say keep the GPS on the dozer where you can move the most material and get it close to grade, then use the grader on the last pass.
I say keep the GPS on the dozer where you can move the most material and get it close to grade, then use the grader on the last pass.
DPete
Senior Member
I never really thought a dozer was a finish machine, never get done chasing berms and every time you turn you skuff the job. Grader foe me to trim and finish. DP
Deas Plant
Senior Member
GPS or Laser
Hi, Folks.
Interesting question. Until recently, I had not used GPS but had used laser extensively on track loaders to cut levels to +/- around 1/2", I have alos used laser on a dozer for the same sort of work, without being concerned about the grouser marks.
When I used GPS for the first time, I was on a site where they were using the dozer that I was operating and a GPS-equipped excavator to do detail work and monitor the levels of 2 or 3 other excavators being used to load bulk into ADT's. With a little practice, I found it relatively easy to get levels to within +/- around 1 3/4" or about 40 mm. However, as I understand it, unless GPS is controling the cut, it is very hard to get a lot closer than that. As Squizzy said, GPS is not very accurate for grades, great for position but not flash for grade. After all, GPS does stand for Global Positioning Satellite - not Grade Perfectly, See. And the GPS system that I used DID require a well set-up base station as part of the system to enable it to make its triangulation calculations. This alone makes it relatively impractical for small job sites, especially where levels are the main priority.
Hi, Folks.
Interesting question. Until recently, I had not used GPS but had used laser extensively on track loaders to cut levels to +/- around 1/2", I have alos used laser on a dozer for the same sort of work, without being concerned about the grouser marks.
When I used GPS for the first time, I was on a site where they were using the dozer that I was operating and a GPS-equipped excavator to do detail work and monitor the levels of 2 or 3 other excavators being used to load bulk into ADT's. With a little practice, I found it relatively easy to get levels to within +/- around 1 3/4" or about 40 mm. However, as I understand it, unless GPS is controling the cut, it is very hard to get a lot closer than that. As Squizzy said, GPS is not very accurate for grades, great for position but not flash for grade. After all, GPS does stand for Global Positioning Satellite - not Grade Perfectly, See. And the GPS system that I used DID require a well set-up base station as part of the system to enable it to make its triangulation calculations. This alone makes it relatively impractical for small job sites, especially where levels are the main priority.
Matt McGowan
Active Member
Topcon Millimeter GPS
Topcon advertises an accuracy of +/- 1/4" using their Millimeter GPS system. In this system GPS is used for the horizontal control while a laser is used to control elevation. My cousins run this system and say that other than needing a total station instrument to do the initial setup, the Millimeter GPS rover can handle all the remaing layout for the non GPS equiped machines.
The stumbling block for small to medium size contractors seems to be the lack of ability to build the digital terrain models in the computer. These are the models (programs) that give GPS equipment information to grade the
the site properly.
I should also note that the need for base stations will be greatly reduced as systems are being deployed where equipment on cell phone towers will take over this function. At least here in the mid-atlantic area. Eventually the only time you would need a base station is when you are out in the boonies and don't have cell phone reception.
Matt
Topcon advertises an accuracy of +/- 1/4" using their Millimeter GPS system. In this system GPS is used for the horizontal control while a laser is used to control elevation. My cousins run this system and say that other than needing a total station instrument to do the initial setup, the Millimeter GPS rover can handle all the remaing layout for the non GPS equiped machines.
The stumbling block for small to medium size contractors seems to be the lack of ability to build the digital terrain models in the computer. These are the models (programs) that give GPS equipment information to grade the
the site properly.
I should also note that the need for base stations will be greatly reduced as systems are being deployed where equipment on cell phone towers will take over this function. At least here in the mid-atlantic area. Eventually the only time you would need a base station is when you are out in the boonies and don't have cell phone reception.
Matt
Last edited:
When we first got our GPS system we were told that it wasn't practical to use on sites that we were only going to be on for two or three days. But lately I've been using it quite a bit on small building pads and even small waterways. It only takes about 10 minutes to set up the base on a tripod and calibrate a new base position. I can then program a level or a slope right in the machine. On bigger jobs we set a post to mount the base on.
We have the computer program to draw our own designs, it's really pretty easy. In the winter or on a rain day I'll go out to the site, set up the base and rover and topo the site then take that back to office. If we have a good copy of the finished plan we can draw up the design in a few hours. Or if the plan changes on site I can just take my flash card in and revise it.
I totally disagree that GPS isn't accurate for grade. You can easily get within .05'. You just have to cut down to grade in .10' increments. But then I have in on a D6M, so I'm a little lacking in horsepower, I have to take little bites. But it's still faster, easier, and cheaper than having to set and use grade stakes.
We have the computer program to draw our own designs, it's really pretty easy. In the winter or on a rain day I'll go out to the site, set up the base and rover and topo the site then take that back to office. If we have a good copy of the finished plan we can draw up the design in a few hours. Or if the plan changes on site I can just take my flash card in and revise it.
I totally disagree that GPS isn't accurate for grade. You can easily get within .05'. You just have to cut down to grade in .10' increments. But then I have in on a D6M, so I'm a little lacking in horsepower, I have to take little bites. But it's still faster, easier, and cheaper than having to set and use grade stakes.
Deas Plant
Senior Member
GPS accuracy.
Hi, Pushcat.
You are entitled to your opinion about GPS grade accuracy. However, I would point out that you are talking 0.05 of a foot - which is better than the 1 3/4" that I mentioned but I'd still like to see it do the work that I am doing now without having GPS actually controlling the machine's cut.
I am now back working in a job where we are REQUIRED to cut levels to less than half of the above-mentioned 1 3/4" tolerance, more in the region of +/- 1/2" to 3/4" with track loaders with 4-in-1 buckets, excavators with tilting buckets or a Cat D5B wide gauge dozer. The track loaders and excavators also have spreader bars like the ones that skid-steers use but on steriods. No GPS system that I have used will do that. I am not saying that there is NO pure GPS system that will do it. All I am saying is that I have no knowledge of any that will. We use laser monitoring only for this work. The laser does NOT control the machine's cut. That is still left to the operator.
GPS for positioning combined with laser for grade is a whole different ball game and may well be more 'betterer' for fine work but it still has a little problem when it comes to working a job like your average subdivision where levels may vary HUGELY, by many yards even, across a given site. At least GPS on its own will get you in the ball park for levels in these situations.
I have been told that there are now systems that use multiple laser beams in combination with GPS to plot the location and match it with the correct laser levels for that location. That could be a lotta laser beams at about 1/4" apart to cover something like the subdivision mentioned above. Sounds pretty technical to me. And expensive??????
Hi, Pushcat.
You are entitled to your opinion about GPS grade accuracy. However, I would point out that you are talking 0.05 of a foot - which is better than the 1 3/4" that I mentioned but I'd still like to see it do the work that I am doing now without having GPS actually controlling the machine's cut.
I am now back working in a job where we are REQUIRED to cut levels to less than half of the above-mentioned 1 3/4" tolerance, more in the region of +/- 1/2" to 3/4" with track loaders with 4-in-1 buckets, excavators with tilting buckets or a Cat D5B wide gauge dozer. The track loaders and excavators also have spreader bars like the ones that skid-steers use but on steriods. No GPS system that I have used will do that. I am not saying that there is NO pure GPS system that will do it. All I am saying is that I have no knowledge of any that will. We use laser monitoring only for this work. The laser does NOT control the machine's cut. That is still left to the operator.
GPS for positioning combined with laser for grade is a whole different ball game and may well be more 'betterer' for fine work but it still has a little problem when it comes to working a job like your average subdivision where levels may vary HUGELY, by many yards even, across a given site. At least GPS on its own will get you in the ball park for levels in these situations.
I have been told that there are now systems that use multiple laser beams in combination with GPS to plot the location and match it with the correct laser levels for that location. That could be a lotta laser beams at about 1/4" apart to cover something like the subdivision mentioned above. Sounds pretty technical to me. And expensive??????
mtb345
Well-Known Member
the reason i asked because we did a job a1000 ft road and the dozer operator would get it + - 1 in and the laboerers would pull a string from center of road to edge of road to maintain crown measure 3in down from the string to allow for mix and rake all the imperfection [tracks and wind rows] by hand. i thought theres abetter way i know grader 1500 min but it cheraper this way so he says
Yes, nearly every job I do is required to be within an inch or less, and .05' is a hair over a half inch. I'm just saying I have no problem getting within that tolerance with a GPS dozer, you just have to learn the quirks of your machine. You can't run all out full throttle when cutting your final grade, the hydraulics can't keep up with what the computer is telling it what to do. Also the type of material makes a big difference in how the material cuts out, in slabs or crumbly, we all know this.
The job I'm on right now consists of a 13 acre office,shop,warehouse complex. It has two 120x240 and one 75x75 building pads, with concrete drives and parking, all sitting on 6 inches crushed stone. The remainder of the site gets covered with one foot of crushed rock. This is all bid work. If I'm just an inch high with my rock thats over $20,000! Just today the concrete crew setup batter boards on the office pad I rocked, pulled string lines and was well within a half inch, most was dead on. Also have multiple surface drainage flows. All this without having to have surveyors set a single hub or grade stake. That alone saves $12-15,000 over the duration of the project. It took eight sometimes very wet working days with two very green scraper operators and somedays just myself to finish the dirt grade. Never had to leave the machine once to check or change grade, just had to keep my operators cutting in front of me and leveling their fill. Was within two hours of finishing when the owner decided to move the buildings. No big deal, changed the design on the flash card and the next morning at 7 we were ready to cut grade again, didn't need to wait for an engineer or surveyors to lay it out for me.
Yeah, it's not just my opinion that GPS works, it's a fact for me. I use to swear that a 953 was just the cat's pajama's for fine grading. And I still do quite a bit of it, but for the pure economics of it, GPS is the way to go. It's a high cost upfront, but long term it pays. Speed, efficiency, moving dirt once and placing it right. I'm paid hourly but I get a pretty hefty bonus at the end of the year based on my productivity so I'm all for it.
I don't want to come across as being snippy, but it works good for me. It took almost three years to finally being comfortable and competent with it. If it's not working for someone, either somethings not right or you need to keep working with it.
The job I'm on right now consists of a 13 acre office,shop,warehouse complex. It has two 120x240 and one 75x75 building pads, with concrete drives and parking, all sitting on 6 inches crushed stone. The remainder of the site gets covered with one foot of crushed rock. This is all bid work. If I'm just an inch high with my rock thats over $20,000! Just today the concrete crew setup batter boards on the office pad I rocked, pulled string lines and was well within a half inch, most was dead on. Also have multiple surface drainage flows. All this without having to have surveyors set a single hub or grade stake. That alone saves $12-15,000 over the duration of the project. It took eight sometimes very wet working days with two very green scraper operators and somedays just myself to finish the dirt grade. Never had to leave the machine once to check or change grade, just had to keep my operators cutting in front of me and leveling their fill. Was within two hours of finishing when the owner decided to move the buildings. No big deal, changed the design on the flash card and the next morning at 7 we were ready to cut grade again, didn't need to wait for an engineer or surveyors to lay it out for me.
Yeah, it's not just my opinion that GPS works, it's a fact for me. I use to swear that a 953 was just the cat's pajama's for fine grading. And I still do quite a bit of it, but for the pure economics of it, GPS is the way to go. It's a high cost upfront, but long term it pays. Speed, efficiency, moving dirt once and placing it right. I'm paid hourly but I get a pretty hefty bonus at the end of the year based on my productivity so I'm all for it.
I don't want to come across as being snippy, but it works good for me. It took almost three years to finally being comfortable and competent with it. If it's not working for someone, either somethings not right or you need to keep working with it.
Deas Plant
Senior Member
The Answer.
Hi, Pushcat.
You gave the answer to the difference between your experience with GPS and mine in your first paragraph. I gather that your GPS controls the dozer blade. The system I was using did not control the dozer blade. It simply gave readouts on a computer screen for the operator to follow.
Another thing that makes it VERY hard to stay close to grade with this system is the sheer number of corrections that appear on that screen, sometimes as many as 4 or 5 PER SECOND, even if you are standing still with the blade on the ground. At that rate, I doubt there is a man alive who could keep the blade corrections up to it. Most people would have trouble just recognising the readout at that rate of change, which is where GPS controlling the blade comes in.
Thanks for sharing your experiences.
Hi, Pushcat.
You gave the answer to the difference between your experience with GPS and mine in your first paragraph. I gather that your GPS controls the dozer blade. The system I was using did not control the dozer blade. It simply gave readouts on a computer screen for the operator to follow.
Another thing that makes it VERY hard to stay close to grade with this system is the sheer number of corrections that appear on that screen, sometimes as many as 4 or 5 PER SECOND, even if you are standing still with the blade on the ground. At that rate, I doubt there is a man alive who could keep the blade corrections up to it. Most people would have trouble just recognising the readout at that rate of change, which is where GPS controlling the blade comes in.
Thanks for sharing your experiences.
Deas
I have to say I agree with pushcat on this one. My company first tried GPS about 6 years ago, and we started with an indicate only system, such as you talked about. It helped, but we still had to finish with a blade after the dozer was "finished".
3 years ago, we got convinced to try the total machine control system, and added it to a D-6R dozer. WOW What a difference over the prior system! Our production increased 3 fold, and the dozer gets to +/- .04 on a regular basis (about 1/2 inch). The only time we need to follow is if the owner is picky and wants the grouser marks taken out, then a skiploader with a recently promoted laborer drags the track marks out.
Since then, we have added a D-8T and a 14G each with full automatic control systems. We run all Trimble gear, and are very happy with the production. The only place I would see the need for tighter control, such as the millimeter system, would be freeways or airports and the like.
MTB345
I still would not pave on a dozer finish, as there are too many small divots to end up with a smooth paving job. You might get it to pass, but the quality would suffer. Bring a blade, but he won't have to stay long to brush things up.
I have to say I agree with pushcat on this one. My company first tried GPS about 6 years ago, and we started with an indicate only system, such as you talked about. It helped, but we still had to finish with a blade after the dozer was "finished".
3 years ago, we got convinced to try the total machine control system, and added it to a D-6R dozer. WOW What a difference over the prior system! Our production increased 3 fold, and the dozer gets to +/- .04 on a regular basis (about 1/2 inch). The only time we need to follow is if the owner is picky and wants the grouser marks taken out, then a skiploader with a recently promoted laborer drags the track marks out.
Since then, we have added a D-8T and a 14G each with full automatic control systems. We run all Trimble gear, and are very happy with the production. The only place I would see the need for tighter control, such as the millimeter system, would be freeways or airports and the like.
MTB345
I still would not pave on a dozer finish, as there are too many small divots to end up with a smooth paving job. You might get it to pass, but the quality would suffer. Bring a blade, but he won't have to stay long to brush things up.
JimBruce42
Senior Member
GPS quirks
I have to agree with pushcat and jdofmeni,
The company I work for has GPS on almost all our dozers, 815's, several of our mass excavators, and a combo of GPS and total station systems on our graders and rovers for checking grade or placing grade stakes for the few things we don't have GPS on (like most pipe crews). :usa
However, I think all but a few of those systems are NOT automatics, we have an older auto system on a D6 and found it slow and kind of sloppy. That being said, we did just demo'ed the latest system last fall and it was faster, and great working with loose material (like respreading topsoil or stoning a road):notworthy . However, at higher speeds and in harder material, even a novice operator like myself, found I could hold grade within a tenth or two and at higher speeds than the automatics:drinkup
Somethings that can give GPS problems, even in a clear sky, is when the satellites are either all at the same spot in the sky or all towards the horizon. It is harder to triangulate when this happens and you're errors can increase. :bash
I have to agree with pushcat and jdofmeni,
The company I work for has GPS on almost all our dozers, 815's, several of our mass excavators, and a combo of GPS and total station systems on our graders and rovers for checking grade or placing grade stakes for the few things we don't have GPS on (like most pipe crews). :usa
However, I think all but a few of those systems are NOT automatics, we have an older auto system on a D6 and found it slow and kind of sloppy. That being said, we did just demo'ed the latest system last fall and it was faster, and great working with loose material (like respreading topsoil or stoning a road):notworthy . However, at higher speeds and in harder material, even a novice operator like myself, found I could hold grade within a tenth or two and at higher speeds than the automatics:drinkup
Somethings that can give GPS problems, even in a clear sky, is when the satellites are either all at the same spot in the sky or all towards the horizon. It is harder to triangulate when this happens and you're errors can increase. :bash
dirtdigger
Member
We have several drainage contractors in Michigan, and around the midwest using RTK GPS to control grade on their drainage plows. The accuracy is within a half inch (as stated by others) and a base station (tripod) is set up in the field.
The contractors that can afford it ($65,000 for set up with machine control) use it exclusively and got rid of their laser equipment all together.
For those unfamiliar with agricultural drainage, it is plastic tubing installed at an average of 3 foot depth, with grade running downhill toward the outlet ditch or pipe. Grade is crucial on all of our work.
I am a member of the Michigan Land Improvement Contractors of America, and we are doing a field day demonstration in Michigan August 1 & 2, 2007, for any local guys here that are interested.
We will have a drainage plow, dozer and possibly a grader all fitted with RTK GPS of different brands. Also we will be showing crop spraying and ag applications using GPS.
(I'm new here, so I hope the plug is allowed )
The contractors that can afford it ($65,000 for set up with machine control) use it exclusively and got rid of their laser equipment all together.
For those unfamiliar with agricultural drainage, it is plastic tubing installed at an average of 3 foot depth, with grade running downhill toward the outlet ditch or pipe. Grade is crucial on all of our work.
I am a member of the Michigan Land Improvement Contractors of America, and we are doing a field day demonstration in Michigan August 1 & 2, 2007, for any local guys here that are interested.
We will have a drainage plow, dozer and possibly a grader all fitted with RTK GPS of different brands. Also we will be showing crop spraying and ag applications using GPS.
(I'm new here, so I hope the plug is allowed
)grunk36
Well-Known Member
- Joined
- Jun 9, 2008
- Messages
- 166
- Location
- denmark
- Occupation
- trainer/technical support with TRIMBLE/SITECH denm
accugrade precision
i drive a D6R series 3 with accugrade and i have my own base station with me which i mount on a tripod types new base and then i can grade with a tolerance within 10-20 mm i have made sevral parking lots that way so its very precise but on highways here in denmark we always use motor graders with ats to do the last finish it can make a more smooth suface without backdragging
i drive a D6R series 3 with accugrade and i have my own base station with me which i mount on a tripod types new base and then i can grade with a tolerance within 10-20 mm i have made sevral parking lots that way so its very precise but on highways here in denmark we always use motor graders with ats to do the last finish it can make a more smooth suface without backdragging
dozerman400
Well-Known Member
Don't need GPS or a grader. I have graded plenty of lots for pavers with a dozer, never had a complaint yet. I do like using GPS and graders but they are not aways available.
Kman9090
Senior Member
At Lambrecht we used a GPS Trimmer which was awesome, got it close with a dozer and let the trimmer go. It just depends on what state your in and what the price of the rocks is. As well if you have to do subgrade treatment with lime or cement then a blade is almost a must unless you rough it in with a dozer and let the trimmer cut it a few days later.