 At stairs, detectable warning surfaces are required (long bars that in the United States are called "directional bars" but are placed at perpendicular to the main path of travel), whereas offset truncated dome detectable warning surfaces are used for ramps, elevated platforms (like those found at the edges of boarding platforms in transit facilities), and at other areas where pedestrian ways blend with vehicular ways.Tijuana uses landmark installations before crosswalks that are similar to those used in California.There are, however, no installations of tactile ground surface indicators.