Mumbai: Mumbai division of Central Railway will today operate a megablock on its Harbor line between Chhatrapati Shivaji Maharaj Terminus (CSMT) and Chunabhatti/Bandra sections to carry out various engineering and maintenance works. There will be no megablock on the main line between CSMT and Karjat/Kasara, which will provide relief to many passengers traveling by local trains on Sunday. On the Harbor Line, there will be a block from 11:40 am to 4:40 pm on CSMT-Chunabhatti/Bandra Down Line and from 11:10 am to 4:10 pm on Chunabhatti/Bandra-CSMT Up Line. Special services will run at a frequency of 20 minutes between Panvel and Kurla (Platform No. 8) during the block period. Harbor line passengers are allowed to travel on the main line and Western Railways till 6 pm during the block period, an official said.