A recently developed Flexible Track System Model integrated with a multibody dynamics software tool was used to simulate the dynamic interaction between a vehicle and two innovative slab track designs, comparing their performance with respect to conventional ballasted track. The design concepts are presented and the modelling assumptions are given. Simulations are then carried out to quantify, for example, the impact of ballasted track degraded state using the case of a hanging sleeper. In comparison, the benefit of the two innovative track designs is highlighted as they prevent this type of localised defect from occurring. The alternative track designs were also shown to be capable of carrying a vehicle safely and with less impact on the system over a localised weakened formation support, by simulating a washout event.