Complex sentence: In 2000, CZRY Carrizo Gorge Railway became interested in finishing SD&IV's repairs to the Desert Line, by signing a contract, SD&IV sub-contracted the Desert Line's responsibility to CZRY, which resumed work in 2000 and reopening the Carrizo Gorge in 2004 for freight service.
Split into simpler sentences: In 2000, CZRY Carrizo Gorge Railway became interested in finishing the SD&IY's repairs to the Desert Line. By signing a contract, SD&IY sub-contracted the Desert Line's responsibility to CZRY, which resumed work in 2000 and reopened the Carrizo Gorge in 2004 for freight service.