Complex sentence: It was later divided into two separate stretches, between junctions 16 and 19 and junctions 13 and 15 with the stretch between junctions 16 and 19 currently under construction from December 2015 and the stretch between junctions 13 and 15 set to commence from March 2018.
Split into simpler sentences: It was later divided into two separate stretches, between junctions 16 and 19 and junctions 13 and 15. The stretch between junctions 16 and 19 has been currently under construction from December 2015 while the stretch between junctions 13 and 15 is set to commence from March 2018.