Complex sentence: A railway line connecting Gretna and Annan passes through the disused Eastriggs railway station, for which there are plans to provide a smaller replacement once the upgrade from single to double tracks has been completed, enabling simultaneous passenger and freight traffic.
Split into simpler sentences: A railway line connecting Gretna and Annan passes through Eastriggs railway station. This station is disused, but there are plans to provide a smaller replacement once the line has been upgraded from single to double track, enabling simultaneous passenger and freight traffic.