Cold Mill & Overlay Adjacent to Full Depth Road Widening
Cold Mill & Overlay Adjacent to Full Depth Road Widening
(OP)
I have been the roadway designer on multiple roadway widening project for various cities. I have had a few cities request that we provide a 2 foot wide and 2" thick cold mill and overlay adjacent to the saw cut line which is typically 1' from the edge of gutter. I have also seen this on utility trench details as well.
What is the purpose of this? I always thought that it was to allow for the top 2" wearing course to be laid together and it would somehow create a better join condition. This logic made sense to me, so I typically provide the cold milling.
I am now working for another city which is absolutely against this idea and thinks that the cold milling won't produce as clean and straight of an edge. I have never heard of this being an issue and think that maybe the contractor was not using the correct cold milling equipment or techniques to produce a clean and straight edge.
Anyone have any thoughts?
What is the purpose of this? I always thought that it was to allow for the top 2" wearing course to be laid together and it would somehow create a better join condition. This logic made sense to me, so I typically provide the cold milling.
I am now working for another city which is absolutely against this idea and thinks that the cold milling won't produce as clean and straight of an edge. I have never heard of this being an issue and think that maybe the contractor was not using the correct cold milling equipment or techniques to produce a clean and straight edge.
Anyone have any thoughts?





RE: Cold Mill & Overlay Adjacent to Full Depth Road Widening
RE: Cold Mill & Overlay Adjacent to Full Depth Road Widening
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As stated by hmcrae, offsetting the joints in the various layers to provide strength/lessen the effects of water ingress is usually the given reason.
RE: Cold Mill & Overlay Adjacent to Full Depth Road Widening
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RE: Cold Mill & Overlay Adjacent to Full Depth Road Widening
Cold milling does not produce as clean of an edge as saw cutting. Compare the "teeth" of the two pieces of equipment. The mill grinds and tears the pavement away. Rub your hands along the mill's remaining cut face, it is full of voids. Now do you really need a saw cut line next to a mill removal line, probably not but the two are not equal.
Curious as to why the locals like this detail. Are they trying to keep the mill away from gnawing up the curb? I've only had to use this where the State owned the mainline and the local city didn't want to pay to overlay the parking lanes. We milled a line between the two and just overlayed the mainline.