This is the northern end of a loop which runs south as far as King's Gate Junction passing through Shawfair station.
This portion of the line follows a new alignment which was created in 2015 to replace the original course of the Edinburgh and Dalkeith Railway and its later Edinburgh and Hawick Railway (North British Railway) realignments.
It is not a junction in the conventional sense, simply where the single track line from the north doubles.
Newcraighall South Junction is just south of Newcraighall North Junction where the new alignment left the older route.
The junction is within the former west side yard of Millerhill Marshalling Yard, specifically the Millerhill Yard Down Secondary Sorting Sidings which were a group of single ended sidings approached from the north.