Aside from the environmental benefits of using recycled material, plastic ties usually replace timber ties soaked in creosote, the latter being a toxic chemical, and are themselves recyclable. Hybrid plastic railroad ties and composite ties are used in other rail applications such as underground mining operations, industrial zones, humid environments and densely populated areas. Hybrid railroad ties are also used to be partly exchanged with rotten wooden ties, which will result in continuous track stiffness. Hybrid plastic ties and composite ties also offer benefits on bridges and viaducts, because they lead to better distribution of forces and reduction of vibrations into respectively bridge girders or the ballast. This is due to better damping properties of hybrid plastic ties and composite ties, which will decrease the intensity of vibrations as well as the sound production. In 2009, Network Rail announced that it would begin replacing wooden ties with recycled plastic. but I-Plas became insolvent in October 2012.