Panel development is an integral part of longwall planning. Since the longwall can outproduce gateroad development using room-and-pillar mining by up to 10 folds, the strategy for gateroad development is speed, not coal volume, as originally perceived in the 1970s. In fact, in a longwall mine, longwall accounts for 80 to 85% of total mine production while mains and gateroad developments account for the remainder. In the 1970s and early 1980s, nearly all longwall mines were originally designed for room-and-pillar mining, converting later to longwall mining. So there was then gateroad development using the five-entry system. In terms of the amount of development work per unit longwall face advance, the two-entry system requires the least development work. But, the continuous miner development system consists of several pieces of large equipment near the face area, the two-entry system is too crowded for efficient equipment place change.