Complex sentence: The Crossrail service started as recently as 2002, as a first step in exploring demand for reviving formerly extensive suburban rail, which the city had been abandoned by the 1960s when it appeared inflexible compared to the bus network.
Split into simpler sentences: The Crossrail service started as recently as 2002, as a first step in exploring demand for reviving formerly extensive suburban rail network. These routes had been abandoned in the 1960s when it appeared rail travel was inflexible compared to the bus network.