4D BIM adds a new dimension (time) to 3D CAD or solid modelling, it enables a sequence of events to be depicted visually on a time line that has been populated by a 3D model (augmenting traditional Gantt charts and Critical Path (CPM) schedules often used in project management).[1][2][3][4][5][6][7][8] Construction sequences can be reviewed as a series of problems using 4D BIM, enabling users to explore options, manage solutions and optimize results. It enables construction product development, collaborative and transparent project implementation, partnering with the supply chain and production of components, and is in keeping with Egan's vision: "sustained improvement should then be delivered through use of techniques for eliminating waste and increasing value for the customer."