A set of yellow truncated domes can be seen on the down-ramp in a parking lot.
Tactile paving (also called truncated domes, detectable warnings, Tactile Ground Surface Indicators, Tactile Walking Surface Indicators, detectable warning surfaces) is a system of texturedground surface indicator found on footpaths, stairs and train station platforms to assist pedestrians who are visually impaired.
Tactile warnings provide a distinctive surface pattern of truncated domes, cones or bars detectable by long cane or underfoot which are used to alert the visually impaired of approaching streets and hazardous surface or grade changes. There is a disagreement in the design and user community as to whether installing this aid inside buildings may cause a tripping hazard.
Originally instituted at pedestrian crossings and other hazardous road situations by Japan, the United Kingdom, Australia and the United States picked up the standard in the early 1990s, after passage of the Americans with Disabilities Act (ADA). Canada started incorporating them into transportation first in the 1990s, and then added them to other aspects of the built environment in the early 2000s.
Japan was one of the pioneers in the introduction of tactile pavings (subway stop with yellow pavings in Nagoya
The original tactile paving was developed by Seiichi Miyake in 1965. The paving was first introduced in a street in Okayama city, Japan, in 1967. Its use gradually spread in Japan and then around the world.
Today yellow tactile pavings are ubiquitous throughout Japan. For aesthetic reasons, for example in front of hotels, the colour of the paving can change to reflect the colour of the pavement or stone floor. Sometimes the paving contours are produced with steel stripes and dots.
The tactile tiles spread rapidly via their adoption at Japan National Railways (later known as Japan Railway). The system was formally named "Hazard Guide for the Visually Impaired" (視覚障害者誘導用) in 1985. Its modern form can be classified into two types. One has small, round bumps upon the surface of the block, which are felt through a sole. The second type of a block is a directional aid. Long and slender bumps are installed in the surface.
However, many types have been manufactured as an experiment and installed. This has resulted in a situation which may be confusing for both the visually impaired and for the elderly. Usually the color of a tile is used to check the proper direction. If the color is not clear, there may be confusion. This has led to standardisation of the system throughout Japan.
Now, these tiles are spreading throughout the world. There are many tactile tiles installed at subway stations and on sidewalks in Seoul, Korea. The installation situation in Seoul is more challenging than in Japan. Since the surface of various sidewalks in Seoul are not flat, there are many places which do not convey the meaning of a Tactile Tile.
The Tactile Tiles were adopted at each facility used for the Sydney Olympic Games in Australia and are ubiquitous in Australian public transportation facilities. Such a trend has also started in the UK and the US and throughout the world.
These are used for pedestrian crossings. The purpose of the blister surface is to provide a warning to visually impaired people who would otherwise, in the absence of a change of height of > 25 mm, find it difficult differentiate between where the footway ends and the carriageway begins. The surface is therefore an essential safety feature for this group of road users at pedestrian crossing points where the footway is flush to the carriageway to enable wheelchair users to cross unimpeded. The profile of the blister tactile surface consists of rows of flat topped blisters in a square pattern. 
Offset blister tactile
The offset blister tactile is also known as the "platform edge (off-street) warning surface". The purpose of this surface is to warn visually impaired people of the edge of all off-street railway platforms. The off-set blister tactile surface consists of flat-topped domes (blisters), spaced 66.5mm apart from the center of one dome to the next one.
The tactile paving units can be manufactured in any suitable paving material and may be any color that provides a good contrast with the surrounding area to assist partially sighted people. The current guidance recommends that the off-set blister tactile surface be used for all off-street rail platforms including:
- Heavy rail platforms
- Off-street light rapid transit (LRT) platforms
- Underground platforms
It should not be used for on street (LRT) platforms
The lozenge tactile is also known as the platform edge (on-street) warning surface. "The purpose of the platform edge (on-street) warning surface is to warn visually impaired people that they are approaching the edge of an on-street light rapid transit (LRT) platform." The profile of the lozenge tactile warning surface comprises rows of 6mm (±0.5mm) high lozenge shapes, which have rounded edges so as not to cause a trip hazard. The tactile paving units can be manufactured in any suitable paving material. The surface is usually buff colored, but can be any color, other than red that provides a good contrast with the surrounding area to assist partially sighted people.
The lozenge tactile paving units should be installed to a depth of 400mm parallel to the platform edge and a minimum of 500mm back from the edge. It should never be installed closer to the edge than this because pedestrians may not have sufficient time to stop walking once they have detected the tactile warning surface.
Corduroy hazard warning tactile
"The purpose of the corduroy surface is to warn visually impaired people of the presence of specific hazards: steps, level crossings or the approach to the on-street light rapid transit (LRT) platforms. It is also used where a footway joins a shared route. It conveys the message 'hazard, proceed with caution.'"
The profile of the corduroy tactile surface comprises rounded bars running transversely across the direction of pedestrian travel. The bars are 6mm (±0.5) high, 20mm wide and spaced 50mm from the centre of one bar to the centre of the next. The tactile paving units can be manufactured in any suitable paving material. The surface is usually buff coloured, but can be any colour, other than red, that provides a good contrast with the surrounding area to assist partially sighted people.
The corduroy tactile can be used for any situation (other than pedestrian crossings) where visually impaired individuals need to warn of a hazard, such as:
- The top and bottom of stairs
- At the foot of a ramp
- At level crossing
- Where people may unintentionally walk directly on to the platform at a railway station
- Where a footway joins a shared route
Cycle way tactile
"The purpose of the tactile surface used in conjunction with a segregated shared cycle track/footway is to advise visually impaired people of the correct side to enter. The purpose of the central delineator strip is to help visually impaired pedestrians to keep to the pedestrian side."
The cycle way tactile comprises a series of continuous raised, flat-topped bars, each 5mm (±0.5mm) high, 30mm wide and spaced 70mm apart. The central delineator strip should be 12 –20mm high, 150mm wide with sloping sides and a flat top of 50mm. The delineator strip should be made of a white material.
The tactile surface should be used on any segregated shared route where the pedestrian side is not physically separated from the cyclist side. The tactile surface should be laid at the beginning and end of the shared segregated route, at regular intervals along its length and at any junctions with other pedestrians or cyclist routes.
Directional or guidance tactile
"The purpose of the guidance path surface is to guide visually impaired people along a route when the traditional cues, such as a property line or kerb edge, are not available. It can also be used to guide people around obstacles, for example street furniture in a pedestrianized area. The surface has been designed so that people can be guided along the route either by walking on the tactile surface or by maintaining contact with a long cane." The guidance tactile compromises a series of raised, flat-topped bars running in the direction of pedestrian travel. The bars are 5.5mm (±0.5) high, 35mm wide spaced 45mm apart, It is recommended that the guidance path tactile be in a contrasting color to the surrounding area so as to assist partially sighted people. The guidance surface is recommended for use in the following circumstances:
- Where the traditional guidance given by a standard footway between the property line and carriageway does not exist
- Where pedestrians need to be guided around obstacles
- Where a number of visually impaired people need to find a specific location and in transport terminals to guide people between facilities.