Introduction. Cost overruns are a common occurrence in project management. I have covered in an earlier article about the reasons why cost overruns occur. In this post, I will cover the ways to prevent your projects from having cost overruns.. Pay a lot of attention to project planning. Planning is the most essential component of project management and the biggest weapon against cost overruns & delays. Think of all the major scenarios and flesh out the complete scope of the project before a single line is coded.