Complex sentence: The bus/HOV lanes are being converted to express toll lanes as part of the Metro ExpressLanes project, allowing low occupancy vehicles to use the lanes on payment of a fee which will vary dynamically with traffic levels.
Split into simpler sentences: The bus/HOV lanes will be converted to express toll lanes as part of the Metro ExpressLanes project. Sole drivers will be able to use the toll lanes on payment of a fee which will vary dynamically with traffic levels.