Pre-plan is a pre-arrangement aiming at tackling possible emergent events. It is a critical part of emergency 
management system. 
When undertaking real-time command or rehearsal, mereway of text communication is obviously insufficient. 
The pre-plan system shall be visualized so that the ordersand other information can be passed down and exchanged 
in a lucid way. The application of GIS into the pre-plan system is a perfect solution.