Included in this review paper is a brief introduction to geomembranes, their production, the resulting properties, and the current market demand. This introductory information is followed by a discussion on proper design philosophy, including a set of minimum recommended values based on installation survivability. The heart of the paper involves the review of the current areas of geomembrane use in transportation systems. As with all geomembrane applications, the primary function is as a barrier. In the applications cited, the barrier is intended to contain surface water, groundwater, or liquid pollutants. A wide range of applications is emerging whereby the different geomembranes can be used to excellent advantage and in a cost-effective manner. A summary table for each use area is also included. The conclusion gives an idea as to possible future trends.