Drillers passed the halfway mark Thursday in their most advanced evacuation shaft toward 33 men who have been trapped deep underground in a Chilean mine since August, officials said. The operation, referred to as "Plan B" by rescuers, has dug down 333 meters (1,093 feet), more than halfway toward its objective of 630 meters (2,067 feet), said Andres Sougarret, the engineer coordinating rescue operations. The drill has already reached the miners with a tunnel about 30 centimeters (10 inches) in diameter but now is working to more than double its width in order to extract the trapped workers. Officials have said they are unlikely to be able to start pulling out the men until early November. The miners have been trapped underground since a part of the mine collapsed on August 5, blocking the exit. A tall, thin cage has been designed to be sent down the bore hole and allow the men to be pulled out one by one. Two other drilling rigs are also being employed in the effort, with "Plan A" drilling having reached a depth of 548 meters (1,798 feet) of its 702-meter (2,303-foot) objective though that tunnel needs to be widened for the eventual rescue. An oil-drilling rig used in "Plan C," which is using a wider bore that only requires a single operation, has reached a depth of 156 meters (512 feet) toward its goal of 597 meters (1,959 feet), according to Sougarret.