Let's say there is a region with two parts, north and south. This region has a railway and has been urbanized, which can now travel towards northern train line, crossing over a river.
The railway from the southern part of XYZ region has just been extended, which can cross over a river towards the northern train line.
Or
The railway from the southern part of XYZ region has just been extended, which can cross over a river towards northern train line. (please see the picture on the right)
(Added sentence after the comments and an answer)
*The railway from the southern part of XYZ region has just been extended, which crosses over a river towards north.