[abb]

Not to mention each of those cracks represent a weak point in the slab.

When you drive down the interstate, you may visualize it as one continuous concrete ribbon unbroken for miles.

Not so. Concrete paving is a series of individual slabs, with “control joints” spaced about 30’ apart, and spanned by steel dowels to transfer the load from one slab to the next.

When placed, concrete eventually cracks, due to shrinkage as it cures. The trick is making it crack where YOU want it to, where provision can be made to seal the pre-planned joint, and with provision for load transfer.

http://www.cement.org/for-concrete-books-learning/concrete-technology/concrete-construction/contraction-control-joints-in-concrete-flatwork
Placing Joints in Concrete Flatwork: Why, How, and When

https://www.concretenetwork.com/concrete-joints/load-transfer.html
Load Transfer
Transferring loads across joints.

[EarthResearcher333]

>>The trick is making it crack where YOU want it to, where provision can be made to seal the pre-planned joint, and with provision for load transfer.... I think you are speaking to the "choir" here (re: knowledge of pre-planned curing design of concrete forms & seams/cracks) - I'm also assuming that you are not inferring that these drain lines were part of a design approach to have these as "pre-planned" cracks. However, I find it odd that they determined the slab dimension to be at a given thickness rating for the performance of the design (spillway load dynamics), and then end up putting in a "ready to crack" thinning drain line/gravel protrusion into this slab thickness.

[Grampa Dave]

Good stuff.

How do you figure out what needs to be done with the spillway facing south and getting hammered by the sun during the day and the cold nights in that area.

What impact does tons of cold water barely over freezing have on those stress areas when it flows over them?