Prefabricated vertical drains (PVDs), also known as wick drains, are used to accelerate the consolidation process by reducing the distance of the drainage paths. They are made of a plastic core encased by a geotextile. The spacing and the size of PVDs depends on the properties of the hydraulic soil and the desired consolidation time of the project. This method is usually combined with preloading of the soil. The temporary load initially increases pore water pressure and then drain flow occurs. Pore water will flow laterally to the nearest drain following a shorter path reducing the preloading time.