To effectively generate a fast and consistent apartment construction project network, Hyundai and KAIST have developed a case and constraint based project planning expert system for apartment domain, FASTrak-APT, inspired by the fact that human expert project planner uses previous cases for planning a new project and modifies them using her/his knowledge on domain constraints. This largescale, case based and mixed-initiative planning system integrated with intensive constraint-based adaptation utilizes semantic level meta-constraints and human decisions for compensating incomplete cases imbedding specific planning knowledge. The case and constraint based architecture inherently supports cross-checking cases with constraints during the system development and maintenance. This system has drastically reduced the time and effort required for initial project planning, improved the quality and completeness of the generated plans, and is expected to give the company the competitive advantage...