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Bluetop Intervals
Posted by joshselvey on October 16, 2018 at 5:17 pmHello survey world. I have a question about the interval to use when staking bluetops for roadway construction. I work in the public sector and would like to know what the “norm” is for AB and subgrade intervals. I’ve always thought that 50′ for subgrade and 25′ for AB is the normal intervals but my supervisor would like to get a little feedback on this from the community. So any help will be greatly appreciated.
mike-marks replied 5 years, 5 months ago 8 Members · 11 Replies- 11 Replies
Here’s what they do around here http://www.dot.state.ak.us/stwddes/dcsconst/assets/pdf/surveymanual/constsurveyrequire_0603.pdf
We always used 50′ on highway work, unless there was something non-typical going on. Now its every .01′ with machine control. If the operator has to go more than 10′ without something on the screen he starts hollerin’ about needing grade.
Fwiw, for bluetops we used to go every 50′ on tangents, 25′ on curves, and did all PCs, PTs, APs, VPCs and VPTs. This was about 17 years ago.
Thanks for the input. I will pass it along to my supervisor.
100?? In rural sections 50?? in urban sections.
Did you guys have any difference in distance between AB & subgrade
Hey Josh,
Welcome aboard. 50 and 25 foot intervals seems to be the norm, here in Phoenix. Unless there is a vertical curve, something that has minimal fall or if there is the dreaded Bidwell. I tend to give extra in these cases.
Cya around.
Thanks Erik. I had always done it that way before coming into the public sector. Along with all vertical changes. Hope you’re doing well.
We always got plans with final centerline grade and had to calculate our own sideslopes for the dirtgrade, the top of limemix grade, top of gravel grade, curb inlet, manhole, etc.
If the subgrade was 8in rock or compacted RR slag you can have the job, I don’t want it.
Bidwell why would you red top a bridge deck.
For subgrade, every 50′ etc. Except where the grader did such a lousy job (ignored slope stakes) that the subgrade was over +- 1′ off, then no bluetops until he reworked it to get closer to grade. Had some idle time (County employee) where the contractor insisted the way off areas were ready for bluetopping so we got some 24″ hubs and you could see them march along until they were sticking 18″ out of the ground, conversely, dug holes 1′ into grade and tied flagging to the buried turkey tails. He got the picture; I wish I would have taken pictures.
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