D.1.1\1.1M:2015

5.22.4

p. 179

Tolerance is given a +/- [4*a*b(1-a/S)]/S

I assume the (-) tolerance is to allow for the case where the concrete haunch surface will require a "negative" camber in the beam or girder for proper fit between the haunch and flange.

I have not dealt with nor seen a concrete haunch in the field - so just asking.