MUMBAI: To carry out maintenance work of tracks, signaling, and overhead equipment, a jumbo block of five hours is being undertaken today on the Up and Down fast lines between Santacruz and Goregaon stations from 10 am to 3 pm. WR chief spokesperson Vineet Abhishek said that during the block period, all fast line suburban trains will be operated on the slow line between Goregaon and Santacruz stations. Some suburban trains will remain cancelled during the block, and a few Andheri and Borivali trains will run only up to Goregaon on the harbour line, he added. Meanwhile, the Central Railway is organising a megablock on the Matunga–Mulund Up and Down fast lines from 11.05 am to 3.45 pm. The Up fast line services leaving Thane till 3.38 pm will be diverted to the Up slow line at Mulund station, with scheduled halts between Mulund and Matunga stations, before being re-diverted to the Up fast line at Matunga. These trains will arrive at their destinations about 15 minutes behind schedule. On the Harbour line, the block is being carried out on the Panvel–Vashi Up and Down lines from 11.05 am to 4.05 pm (excluding the Port line). The Up Trans-Harbour line services towards Thane, leaving Panvel till 3.53 pm, and Down Trans-Harbour line services towards Panvel, leaving Thane till 3.20 pm, will remain cancelled, an official said. Special local trains will run on the CSMT–Vashi section during the block period. Trans-Harbour line services will be available between Thane–Vashi/Nerul stations, while Port line services will continue to operate during the block.