Complex sentence: The runway of Ljubljana Jože Pučnik Airport was closed to air traffic in April 2010 during which time, the entire length of the asphalt surface of the runway was renovated, as well as the asphalt surface on some parts of the taxiways.
Split into simpler sentences: The runway of Ljubljana Jože Pučnik Airport was closed to air traffic in April 2010. During that time, the entire length of the asphalt surface of the runway was renovated, as well as the asphalt surface on some parts of the taxiways.