Definition from Wiktionary, the free dictionary
at-grade (not comparable)
- (US) Describing a junction or intersection where two or more transport axes cross at the same level (or grade).
- An at-grade intersection may require a traffic-control device such as a stop sign, traffic light or railway signal to manage conflicting traffic.
- (Can we verify(+) this sense?) Railroad built upon an evened, ground level length of land.