BDSIM is a program that uses a suite of high energy physics software including Geant4, CLHEP & ROOT, to seamlessly track particles through a 3- dimensional accelerator model utilising the full range of particles and physics processes from Geant4. BDSIM was originally developed to simulate linear colliders such as the International Linear Collider (ILC), but has more recently been extended for application to the Large Hadron Collider (LHC), and generally to storage rings. The significant modernisation and revision of the implementation undertaken from 2013 to facilitate these simulations is presented here along with an example of the capabilities.