Whilst some regions of space have a speed multiplier in the tens of thousands, there are also regions where the value is less than unity. For example, in the region around the Xendi Sabu system warp speeds are reduced by almost one half - a Cochrane Value of 0.55. These regions, which are commonly nicknamed 'Warp Shallows', are generally more common than warp highways and tend to cover a larger area. Warp shallows can be caused by a variety of phenomena - the Hekaras corridor is a region of relatively normal space which passes through a large warp shallow caused by unusually intense tetryon fields. The Briar Patch is a warp shallow caused by the unusual metaphasic radiation common to the region.
This information is courtesy of the Daystrom Institute Technical Library and copyright Graham Kennedy.