Complex sentence: The East London Transit formed part of a plan for a much larger Thames Gateway Transit service, which would use the Thames Gateway Bridge to connect to the Greenwich Waterfront Transit on the south side of the River Thames.
Split into simpler sentences: The East London Transit formed part of a plan for a much larger Thames Gateway Transit service. It was proposed that it would use the Thames Gateway Bridge to connect to the Greenwich Waterfront Transit on the south side of the River Thames.