Knowing that area, I doubt it's intentional. Old 15 north of there was abandoned (and subsequently submerged) when they built the reservoir. Kellytown Road (which that northern point is on) is a township road. The "END" assembly is located there because that's where the ramp to US 15 NB splits off of the business route, not because that's where the thing ends. The quadrant route ends at the ramp from SB.
