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Engineering standard to determine if DOT has been under/over testing highway during construction

Engineering standard to determine if DOT has been under/over testing highway during construction

Engineering standard to determine if DOT has been under/over testing highway during construction

(OP)
Hello everyone,

I have been given the task of determining whether the DOT I work for has been under/over testing a highway section. I have been referred to Standard E122-09, however this appears to be a standard to determine appropriate sample size to determine a mean based on a single lot. However I am required to determine over/under testing for multiple lots, i.e. a whole highway section.

How do DOT's determine how many samples to take during highway construction? I think that it essentially the crux of my question. Is there a standard that outlines this clearly?

Thank-you!

RE: Engineering standard to determine if DOT has been under/over testing highway during construction

samples of what?

RE: Engineering standard to determine if DOT has been under/over testing highway during construction

Max93....let's assume we are discussing typical highway materials.... soils, concrete, asphalt, and graded aggregate base materials. Each state DOT sets its own criteria for sampling and testing, usually done to accepted industry standards such as AASHTO and ASTM. The frequency of sampling and testing is usually tied to material and construction variability, balancing benefit to cost. It is a statistical exercise to establish a confidence interval as well.

You're on the right track but you might want to call or search other DOT's to ground truth your process. That information is also available through the internet. Search for Florida, Kentucky, Iowa, Wisconsin, Michigan, Washington, Texas, and California. They all have lots of info online.

RE: Engineering standard to determine if DOT has been under/over testing highway during construction

You might also want to compare your current testing requirements to those of the ACoE. They do a lot of roadway and airfield paving, so their UFGS Specifications (available freely online), in the "PART 3 - Execution" portion of a number of their separate specifications will have their representative sampling requirements.
Dave

Thaidavid

RE: Engineering standard to determine if DOT has been under/over testing highway during construction

Here is a link to Colorado DOT for sampling specs, which is fairly typical for most DOTs:

Link

RE: Engineering standard to determine if DOT has been under/over testing highway during construction

Sampling varies according to activity, risk, and many other factors. On top of that DOTs write their own rules, and are not beholden to only do the minimum standard. From the perspective of your project, if you work for the consultant/contractor, the owner is monitoring your work and you are complaining that they are checking too often. Definitely not something to inspire confidence.

RE: Engineering standard to determine if DOT has been under/over testing highway during construction

(OP)
Sorry I typed up a response a couple of days ago but didn't finish it.

Yes we are testing sample materials - concrete and soil/clay etc. are what I am mainly concerned with.

I am working for a DOT and as an almost graduate engineer (only a few subjects left), I have been given this project. I'm learning lots as I go, but I have been thrown into the deep end a little bit.

With concrete sampling, I have been given a bit of a rundown by a professor, unfortunately the contractors sampling wasn't taken uniformly to make it easy on me (i.e. every x cubic yards or yards length, so a lot of what I'm doing is a little rough).

Thank-you all for the advice, it's much appreciated. I have been following your advice, asking others and looking up other DOT samples and I had a read through the ACOE specs as well.

The thing is - without volumes associated with the soils I think I'm a little stuck. Right now I'm working on proctor graphs for moisture/dry density. I was going to try and relate the number of tests in a lot to an increase in a parabolic curves R^2 value. Does that sound reasonable?

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