What makes the traffic signs visible at night?
Traffic signs are covered with retroreflective sheeting materials. These materials are usually made with tiny glass beads embedded in plastic or with a very small, complex pattern of cube corners that work like prisms. Both of these types of retroreflective materials redirect light back towards its source, but the performance of the materials varies. Photographs of various sheeting patterns of both types are shown on the Retroreflective Sheeting Identification Guide produced by the Federal Highway Administration (FHWA), which is available at: HTML, DOC 788 KB, PDF 556 KB.
Traffic signs are covered with retroreflective sheeting materials. These materials are usually made with tiny glass beads embedded in plastic or with a very small, complex pattern of cube corners that work like prisms. Both of these types of retroreflective materials redirect light back towards its source, but the performance of the materials varies. Photographs of various sheeting patterns of both types are shown on the Retroreflective Sheeting Identification Guide produced by the Federal Highway Administration (FHWA), which is available at: HTML, PDF 276 KB.
