A detectable pavement warning assembly includes a web having a plurality of projections attached to one another by linear connectors, a planar cover with a series of apertures for receiving the projections therethrough and an adhesive sheet. In use a rigid substrate such as a sidewalk is selected, and a primer is applied. The web, cover and adhesive sheet all pre-assembled are placed on the primed substrate. Next, the warning assembly is heated with an open flame to soften and fuse the pavement warning assembly with the primed substrate. The projections will remain extended sufficiently above the cover to provide a warning to pedestrians that walk thereon, such as when approaching a traffic area or other hazard.