Original sentence: 56 km long (42 km dedicated high-speed tracks, 14 km modernised lines), was completed on 15 December 2007, but trains did not start to use it until June 14th, 2009.HSL 3 will used by international Thalys and ICE trains only, as opposed to HSL 2 which is also used for fast internal InterCity services
Edited sentence: 56 km long (42 km dedicated high-speed tracks, 14 km modernised lines), it was completed on 15 December 2007, but trains did not start to use it until June 14th, 2009.HSL 3 is used by international Thalys and ICE trains only, as opposed to HSL 2 which is also used for fast internal InterCity services