tactile paving or tenji block on ground surface as guidance or detectable warning to help pedestrians who visually impaired

alert bar blind blister block blue building bump bus cone crossing detectable domes down facility footpath grade guidance guide help impaired indicator long lot netra off offset parking pattern pavement paving pedestrian platform public rail ramp road sidewalk sign signage situation stair station street subway surface system tactile tenji textured train truncated tuna visually walking warning yellow