Complex sentence: The first stage is complete with the construction of the new "Alnwick Lionheart" Station, made necessary by the unavailability of the original site and new buildings on some of the trackbed into the town centre.
Split into simpler sentences: The first stage is complete with the construction of the new "Alnwick Lionheart" Station. This was made necessary by the unavailability of the original site and new buildings on some of the trackbed into the town centre.