however the availability of durable coniferous species such as various firs, pines, and spruces make their use a more economical prospect. Common dimensions are 8' x 14' and 8' x 16'. Thicknesses vary between suppliers from 4.5” to a full 6”. Swamp mats are produced by many small and medium-sized manufacturers, and quality varies dramatically within the industry. Rig mats, another variety of access mats, may also known as wood and steel mats or steel frame mats. These mats are commonly made of spruce, pine, fir or a combination thereof encased in a steel frame, though some suppliers also offer bamboo and fibreglass options. The frame is normally I Beam or HST steel. The steel is used to strengthen the mats, enabling the manufacturers of the mats to build them in larger sizes and to support more weight compared to all other types of mats. Common sizes are 8' x 20', 8' x 30', and 8' x 40'. One great advantage is the ease of repairing the wooden inserts which gives new life to an already long lasting and durable mat. This method of repair can be completed on both I Beam and HST style mats. Mud mats are a combination of a reinforced member (such as metal bars or bamboo) confining geosynthetic fabric in a portable mat, that can be rolled up for ease of transport and deployment. A lightweight, light-duty flexible mat suitable for distributing loads over firm ground to avoid rutting. They are not commonly used for access matting in soft ground conditions. Heavy-Equipment Mats The final category of matting is known as Heavy-Equipment matting. These mats are constructed from the most durable, load-bearing materials, designed to be transited by heavy equipment. One variety of heavy-equipment mat is the Crane mat. Designed for exceptionally heavy use, Crane mats (also known as digging mats, logging mats, or bridge mats) can be used in a wide variety of applications, including: Powerline tower assembly Mining and heavy access roads Module yards, pipe yards, tank farms and staging areas Wind farms Bridge repair and construction Piers and wharves Crane mats are constructed of solid 8”, 10” or 12” timbers and are affixed by steel bolts, providing ground stabilization under extreme weight. The timber species used in these mats is generally Douglas fir and Hemlock as this species of wood has superior strength, durability and resiliency characteristics compared to other western softwood.