ISO 23599:2012

Assistive products for blind and vision-impaired persons - Tactile walking surface indicators

Produits d'assistance pour personnes aveugles ou visuellement affaiblies — Indicateurs tactiles de surfaces de marche

General Information

• Status: Withdrawn
• Publication Date: 01-Mar-2012
• Withdrawal Date: 01-Mar-2012
• ICS: 11.180.30 - Aids for blind or partially sighted people
• Technical Committee: ISO/TC 173 - Assistive products
• Drafting Committee: ISO/TC 173 - Assistive products
• Current Stage: 9599 - Withdrawal of International Standard
• Start Date: 24-Jan-2019
• Completion Date: 13-Dec-2025

Relations

• Revised: ISO 23599:2019 - Assistive products for blind and vision-impaired persons - Tactile walking surface indicators
• Effective Date: 23-Jun-2018

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 23599
First edition
2012-03-01
Assistive products for blind and vision-
impaired persons — Tactile walking
surface indicators
Produits d’assistance pour personnes aveugles ou visuellement
affaiblies — Indicateurs tactiles de surfaces de marche
Reference number
©
ISO 2012
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means,
electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or ISO’s
member body in the country of the requester.
ISO copyright office
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Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail [e-mail]
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Published in Switzerland
ii © ISO 2012 – All rights reserved

Contents Page
Foreword .iv
Introduction . v
1 Scope . 1
2 Terms and definitions . 1
3 General provisions . 3
3.1 General principles . 3
3.2 Detecting and distinguishing TWSIs . 3
4 Requirements and recommendations . 4
4.1 Specifications for shape and dimensions of TWSIs . 4
4.2 Surrounding or adjacent surfaces . 8
4.3 Visual contrast . 9
4.4 Materials .10
4.5 Installation .10
Annex A (informative) Luminance contrast .12
Annex B (informative) Examples of installations of TWSIs in specific situations .15
Bibliography .35
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies
(ISO member bodies). The work of preparing International Standards is normally carried out through ISO
technical committees. Each member body interested in a subject for which a technical committee has been
established has the right to be represented on that committee. International organizations, governmental and
non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International
Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 23599 was prepared by Technical Committee ISO/TC 173, Assistive products for persons with disability.
iv © ISO 2012 – All rights reserved

Introduction
The purpose of this International Standard is to create requirements for tactile walking surface indicators
(TWSIs) for blind or vision-impaired persons.
When blind or vision-impaired persons travel alone they might encounter problems and hazards in various
situations. In order to obtain information for wayfinding, these pedestrians use information available from
the natural and built environment, including tactual, acoustic and visual information. However, environmental
information is not always reliable; it is for this reason that TWSIs perceived through use of a long white cane,
through the soles of the shoes and through use of residual vision have been developed.
TWSIs were invented in Japan in 1965. They are now used around the world to help blind or vision-impaired
persons to travel independently. At present, TWSI patterns and installation methods vary from country to country.
This International Standard aims to provide a basis for a common approach for TWSIs at the international level,
while acknowledging that some differences may be necessary at the local level to accommodate climatic,
geographical, cultural or other issues that might exist.
TWSIs should be designed and installed based on a simple, logical and consistent layout. This will enable
tactile indicators to facilitate not only the independent travel of blind or vision-impaired persons in places they
frequently travel, but also to support their independent travel in places they visit for the first time.
Currently, there are several forms of TWSIs, but the ability to detect differences in tactile patterns through the
soles of the shoes or the long white cane varies depending on individual differences. Therefore, the consolidated
findings of science, technology and experience were employed to define the characteristics of TWSIs that can
be detected and recognized by potential users. Additionally, in order to ensure that TWSIs achieve maximum
effect in conveying information, it is important that they be installed in or on a smooth surface where blind or
vision-impaired persons can identify them without interference from an irregular walking surface.
It is also necessary to ensure that TWSIs can be effectively used by vision-impaired persons as well as people
who are blind. For this purpose, TWSIs should be easily detectable through use of residual vision. This is
achieved through visual contrast between TWSIs and the surrounding or adjacent surface. Visual contrast is
influenced primarily by luminance contrast, and secondarily by difference in colour or tone. In order to have
good visibility, it is necessary to have sufficient illumination without glare and it is important to maintain the
visual contrast between TWSIs and the surrounding or adjacent surface.
While TWSIs should be effective for blind or vision-impaired persons, attention should also be paid to their
surface structure and materials in order to ensure that all pedestrians, including those with impaired mobility,
can safely and effectively negotiate them.
TWSIs are installed in public facilities, buildings used by many people, railway stations and on sidewalks and
other walking surfaces. Attention patterns may be installed in the vicinity of pedestrian crossings, at-grade
kerbs, railway platforms, stairs, ramps, escalators, travelators, elevators, etc. Guiding patterns may be used
alone or in combination with attention patterns in order to indicate the walking route from one place to another.
INTERNATIONAL STANDARD ISO 23599:2012(E)
Assistive products for blind and vision-impaired persons —
Tactile walking surface indicators
1 Scope
This International Standard provides product specifications for tactile walking surface indicators (TWSIs) and
recommendations for their installation in order to assist in the safe and independent mobility of blind or vision-
impaired persons.
This International Standard specifies two types of TWSIs: attention patterns and guiding patterns. Both types
can be used indoors and outdoors throughout the built environment where there are insufficient cues for
wayfinding, or at specific hazards.
Some countries have adopted other designs of TWSIs based on the consolidated findings of science,
technology and experience, ensuring that they can be detected and distinguished by most users. National
standards, regulations and guidelines governed by national legislation specify where TWSIs are to be used.
This International Standard is not intended to replace requirements and recommendations contained in such
national standards, regulations or guidelines.
2 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
2.1
attention pattern
TWSI design, calling attention to a hazard only, or to hazards and decision points
NOTE Attention patterns can be installed in the vicinity of pedestrian crossings, at-grade kerbs, railway platforms,
stairs, ramps, escalators, travelators, elevators, etc.
2.2
at-grade kerb
flush kerb
kerb whereby the edge of the walkway is at the same level as adjoining vehicular ways
NOTE See Figures B.10 and B.11.
2.3
CIE Y value
tristimulus value Y of the CIE 1931 standard colorimetric system for reflecting objects
NOTE 1 The CIE Y value equals the percentage value of the luminous reflectance.
NOTE 2 Y = 0 denotes the reflectance of an absolutely black object (no light is reflected). Y = 100 denotes the reflectance
of a perfectly white object (no light is absorbed or transmitted).
2.4
decision point
intersection or change of direction along a path of travel defined by TWSIs
2.5
discrete units
individual domes, cones or elongated bars that are embedded into the ground or floor surfaces
2.6
effective depth
distance between the detectable edges of the TWSIs when measured in the principal direction of travel
NOTE See Figure 1.
2.7
effective width
distance between the detectable edges of the TWSIs when measured perpendicular to the principal
direction of travel
NOTE See Figure 1 and Figure 2.
2.8
guiding pattern
TWSI design, indicating a direction of travel or a landmark
NOTE Guiding patterns can be used alone or in combination with attention patterns in order to indicate the walking
route from one place to another.
2.9
hazard
any area or element in, or adjacent to, a direction of travel, which may place people at risk of injury
2.10
illuminance
amount of luminous flux to a surface per unit area
NOTE 1 The SI unit for illuminance is lux (lx).
NOTE 2 See Reference [6] for further details.
2.11
integrated units
domes, cones or elongated bars on a base surface or plate, incorporated as a single unit
2.12
luminance
amount of light reflected or emitted from a surface in a given direction
NOTE 1 The SI unit for luminance is candela per square metre (cd/m ).
NOTE 2 See Reference [6] for further details.
2.13
luminance contrast
value of comparison of the luminance of two surfaces
2.14
LRV
light reflectance value
proportion of visible light reflected by a surface at all wavelengths and directions when illuminated by a light source
NOTE 1 LRV is also known as the luminance reflectance factor.
NOTE 2 LRV is expressed on a scale of 0 to 100, with a value of 0 points for pure black and a value of 100 points
for pure white.
2.15
reflectance
ratio of light reflected in a given direction by a surface
NOTE See Reference [6] for further details.
2 © ISO 2012 – All rights reserved

2.16
TWSI
tactile walking surface indicator
standardized walking surface used for information by blind or vision-impaired persons
2.17
truncated domes or cones
type of attention pattern also referred to as flat-topped domes or cones
3 General provisions
3.1 General principles
Wayfinding and mobility can be achieved through good design of facilities, including clear accessible paths of
travel with built and natural guiding elements, such as edges and surfaces that can be followed tactually and
visually. TWSIs should not be a substitute for poor design.
TWSIs shall be installed where no built or natural guiding elements can be provided.
Though TWSIs are used by blind or vision-impaired persons, the design and installation of TWSIs shall take
into consideration the needs of people with mobility impairments.
a) All TWSIs shall:
— be easily detectable from the surrounding or adjacent surface by raised tactile profiles and visual contrast;
— maintain detectability throughout their lives;
— be designed to prevent tripping;
— be slip-resistant;
— be used in a logical and sequential manner;
— be installed consistently to enable them to be interpreted by users; and
— be of sufficient depth in the direction of travel to provide adequate detectability and appropriate response
by the users, such as stopping and turning.
b) Attention TWSIs shall:
— be distinguishable from guiding TWSIs; and
— extend across the full width of an accessible path of travel and perpendicular to the direction of travel when
approaching a hazard.
3.2 Detecting and distinguishing TWSIs
3.2.1 General
TWSIs shall be easily detectable from the surrounding or adjacent surface by raised tactile profiles and visual
contrast. TWSIs shall be distinguishable from each other.
3.2.2 Tactile contrast
TWSIs shall be detectable by blind or vision-impaired persons through the soles of their shoes and by a
long white cane.
When attention patterns and guiding patterns are combined, blind or vision-impaired persons shall be able to
distinguish clearly between them, identify both and remember the meaning of each one.
s
Surrounding or adjacent surfaces shall be smooth to enable TWSIs to be detected and distinguished
(see 4.2).
3.2.3 Visual contrast
TWSIs shall be readily detectable and distinguishable from the surrounding or adjacent surfaces by visually
impaired people. Perception of visual contrast is enhanced by high illumination (see 4.3 and Annex A).
3.2.4 Design for prevention of tripping
Truncated domes or cones and elongated bars shall have bevelled or rounded edges to decrease the likelihood
of tripping and to enhance safety and negotiability for people with mobility impairments.
4 Requirements and recommendations
4.1 Specifications for shape and dimensions of TWSIs
4.1.1 General
TWSIs shall be easily detectable from the surrounding or adjacent surface by raised tactile profiles. This can
be achieved by complying with the shape and dimensions specified below.
4.1.2 Attention patterns
4.1.2.1 Arrangements
Truncated domes or cones should be arranged in a square grid, parallel or diagonal at 45° to the principal
direction of travel (see Figure 1).
b b
s
d
d 1
d
d 2
sss s √2s √2s √2s
a)  Parallel to the principal direction of travel b)  Diagonal at 45° to the principal direction of
travel
4 © ISO 2012 – All rights reserved
s
s
h
p
h
p
Key
1 principal direction of travel
s spacing between the centres of adjacent truncated domes or cones
d top diameter of truncated domes or cones
d bottom diameter of truncated domes or cones
h height of truncated domes or cones
b effective width
p effective depth
Figure 1 — Spacing and dimensions of truncated domes or cones
4.1.2.2 Height
The height of truncated domes or cones shall be 4 mm to 5 mm (see Figure 2).
In indoor environments with exceptionally smooth surfaces, the minimum height of 4 mm may be preferable.
NOTE When truncated domes or cones are surrounded by exceptionally smooth surfaces, such as terrazzo, plastic or
rubber, they can be detected more easily than when they are surrounded by rougher surfaces, such as brushed concrete,
bricks or manufactured pavers. A height that is more than what is necessary for reliable detection can cause tripping.
4.1.2.3 Diameter
The top diameter of truncated domes or cones shall range from 12 mm to 25 mm, as shown in Table 1, and the
bottom diameter of truncated domes or cones shall be (10 ± 1) mm greater than the top diameter (see Figure 1).
[32][33]
NOTE Systematic research carried out on truncated domes or cones of various dimensions indicates that a
top diameter of 12 mm is the optimal size for blind or vision-impaired persons to detect and distinguish through the soles
of their shoes. Experiences indicate that the optimal top diameter for other groups within the community could be greater.
4.1.2.4 Spacing
The spacing refers to the shortest distance between the centres of two adjacent truncated domes or cones
which may be parallel or diagonal at 45° to the direction of travel. The spacing shall be within the ranges shown
in relation to the top diameter in Table 1. The tolerance of the top diameter shall be ±1 mm.
Table 1 — Top diameter and corresponding spacing of truncated domes or cones
Top diameter of truncated
Spacing
domes or cones
mm
mm
12 42 to 61
15 45 to 63
18 48 to 65
20 50 to 68
25 55 to 70
4.1.3 Guiding patterns
4.1.3.1 Arrangements
A guiding pattern shall be constructed of parallel flat-topped elongated bars (see Figure 2) or sinusoidal ribs
(see Figure 3).
NOTE Flat-topped elongated bars are the most commonly used guiding pattern, though sinusoidal rib patterns are used in
geographic areas where snow is common. Sinusoidal patterns are less easily damaged by snow ploughs than flat-topped bars.
b
b
b
ss s
Key
1 principal direction of travel
2 drainage gap between the top of flat-topped elongated bars
b top width of flat-topped elongated bars
b bottom width of flat-topped elongated bars
s spacing between the axes of adjacent flat-topped elongated bars
h height of flat-topped elongated bars
l length of the top of flat-topped elongated bars
l length of the base of flat-topped elongated bars
b effective width
Figure 2 — Spacing and dimensions of flat-topped elongated bars
6 © ISO 2012 – All rights reserved
h
l
l
aa aa aa
rrsss sss
Key
1 principal direction of travel
r distance between the edge of the pattern and the axis closest to the edge (0,5 × s)
s spacing between the axes of adjacent sinusoidal ribs
h height of sinusoidal ribs
l length of the top of sinusoidal ribs
a
40 to 52 mm.
b
4 to 5 mm.
c
≥ 270 mm.
Figure 3 — Spacing and dimensions of sinusoidal ribs
4.1.3.2 Specifications for flat-topped elongated bars
4.1.3.2.1 Height
The height of flat-topped elongated bars shall be 4 mm to 5 mm (see Figure 2).
In indoor environments with exceptionally smooth surfaces, the minimum height of 4 mm may be preferable.
NOTE When flat-topped elongated bars are surrounded by exceptionally smooth surfaces, such as terrazzo, plastic or
rubber, they can be detected more easily than when they are surrounded by rougher surfaces, such as brushed concrete,
bricks or manufactured pavers. A height that is more than what is necessary for reliable detection can cause tripping.
4.1.3.2.2 Width
The top width of flat-topped elongated bars shall range from 17 mm to 30 mm, as shown in Table 2. The bottom
width shall be (10 ± 1) mm wider than the top (see Figure 2).
[32][33]
NOTE Systematic research carried out on flat-topped elongated bars of various dimensions indicates that a top
width of 17 mm is the optimal size for blind or vision-impaired persons to detect and distinguish through the soles of their
shoes. Experiences indicate that the optimal top width for other groups within the community could be greater.
b c
h
l
45° 45°
4.1.3.2.3 Spacing
The spacing refers to the distance between the axes of adjacent flat-topped elongated bars. The distance shall
be in relation to the top width, as shown in Table 2. The tolerance of the top width shall be ±1 mm.
Table 2 — Top width and corresponding spacing
of axes of flat-topped elongated bars
Top width of flat-topped
Spacing
elongated bars
mm
mm
17 57 to 78
20 60 to 80
25 65 to 83
30 70 to 85
4.1.3.2.4 Length
The top length of flat-topped elongated bars shall be more than 270 mm and the bottom length shall be
(10 ± 1) mm longer than the top. Where there is a risk of water ponding between the flat-topped elongated bars,
a drainage gap of 10 mm to 30 mm shall be provided (see Figure 2).
NOTE It is easier for blind or vision-impaired persons to follow guiding patterns that are as continuous as possible.
4.1.3.2.5 Continuity
The distance between the ends of flat-topped elongated bars should be no more than 30 mm.
4.1.3.3 Specifications for sinusoidal rib pattern
4.1.3.3.1 Height of wave crests
The difference in level between the wave crest and the wave trough of sinusoidal rib patterns shall be 4 mm to
5 mm (see Figure 3).
In indoor environments with exceptionally smooth surfaces, the minimum height of 4 mm may be preferable.
NOTE When sinusoidal rib patterns are surrounded by exceptionally smooth surfaces, such as terrazzo, plastic or
rubber, they can be detected more easily than when they are surrounded by rougher surfaces, such as brushed concrete,
bricks or manufactured pavers. A height that is more than what is necessary for reliable detection may cause tripping.
4.1.3.3.2 Spacing between wave crests
The distance between the axes of two adjacent wave crests of sinusoidal rib patterns shall be 40 mm to 52 mm
(see Figure 3).
4.1.3.3.3 Length of sinusoidal ribs
The length of the sinusoidal ribs should be at least 270 mm. Where there is a risk of water ponding between
the sinusoidal bars, a drainage gap of 10 mm to 30 mm shall be provided.
4.2 Surrounding or adjacent surfaces
Surrounding or adjacent surfaces shall be smooth to enable TWSIs to be detected and distinguished. Gaps
between joints should be avoided or shall have a maximum of 10 mm in width and 2 mm in depth. For paving
units with bevelled edges, the width of the gap shall be measured on the top of the paving units (see Figure 4).
8 © ISO 2012 – All rights reserved

a a a
b b b
b b b
p p p
Key
b width of the gaps between joints
p depth of the gaps between joints
a
≤ 10 mm.
b
≤ 2 mm.
Figure 4 — Gaps between joints
When more than 6 % of the surrounding or adjacent surface area is covered with gaps, a smooth surface shall
be provided on either side of the TWSIs, extending to a minimum width of 600 mm, to ensure the required
tactile contrast.
EXAMPLE For paving units equal to or less than 200 mm × 200 mm, the gaps would be a maximum of 5,5 mm.
4.3 Visual contrast
4.3.1 General
Visual contrast has two components: luminance contrast and difference in colour. For vision-impaired persons,
luminance contrast is essential. Difference in colour or tone may supplement luminance contrast.
4.3.2 Luminance contrast
The luminance contrast value between TWSIs and surrounding or adjacent surfaces shall be greater than 30 %
using the Michelson Contrast formula.
When TWSIs are discrete units, luminance contrast should be 50 % or greater.
Where TWSIs are used for hazards, the luminance contrast value should be 50 % or greater.
The reflectance value (CIE Y value) of the lighter surface shall be a minimum of 40 points.
When the required luminance contrast between TWSIs and the surrounding or adjacent surface cannot be
achieved, a continuous adjoining band of compliant contrast shall be used. The contrasting band shall have a
minimum width of 100 mm.
4.3.3 Calculation of the luminance contrast value
The luminance contrast value (%), shall be calculated using the following formula, known as Michelson Contrast, C :
M
LL−
()
C = ×100
M
LL+
()
where
L is the value of luminance on a lighter surface, expressed in cd/m ;
L is the value of luminance on a darker surface, expressed in cd/m .
When luminance values are not available, but CIE Y values are available, the values Y and Y can be substituted
1 2
for L and L
1 2.
NOTE The CIE Y value is identical to the LRV.
When the CIE Y values or the LRVs of the two surfaces to be compared are known, these values can be used
to determine the luminance contrast. Otherwise, a measurement of luminance or reflectance is required to
determine the luminance contrast. For measurement methods, see A.2.
4.3.4 Maintenance of minimum luminance contrast
The minimum luminance contrast between TWSIs and surrounding or adjacent surfaces shall be achieved and
maintained throughout their life. Deterioration and maintenance shall be considered at installation.
4.3.5 Measurement condition
Luminance and reflectance values should be measured under stable or controlled lighting conditions and in dry
and wet conditions, as appropriate. For the measurement method, see A.2.
4.3.6 Difference in colour or tone
Difference in colour or tone between TWSIs and surrounding or adjacent surfaces may be used to increase
detectability.
Combinations of red tones and green tones shall be avoided because the most common colour deficiency is
of the red-green type.
NOTE 1 Vision-impaired persons often have deficient colour vision. They can, however, retain luminance sensitivity
even when colour sensitivity is severely decreased.
NOTE 2 Safety yellow, as defined in ISO 3864-1, has the best colour conspicuity (according to research into vision-
[45][48][49]
impaired persons ).
4.3.7 Illumination
TWSIs should be sufficiently illuminated to ensure visual detection by vision-impaired persons.
4.4 Materials
TWSIs shall be made of materials that are durable and slip-resistant.
NOTE Refer to national standards for slip resistance.
4.5 Installation
4.5.1 General
This subclause gives the basic principles and specifications for the installation of TWSIs. Examples are
provided in Annex B.
National requirements for the installation of TWSIs take into consideration existing national conditions, design
requirements for the accessible built environment, and national standards, regulations or guidelines governed
by national legislation.
For safety considerations, minimum depth and width dimensions for installation of TWSIs might need to be
greater than those specified in this International Standard, because greater depth and width dimensions
increase the probability of detection.
10 © ISO 2012 – All rights reserved

When TWSIs are embedded as integrated units, the base of the TWSIs shall be level with the surrounding or
adjacent surface. When integrated units are applied on top of existing surfaces, the maximum height of the
base plate shall not exceed 3 mm and the TWSIs shall have bevelled edges (see Figure 5).
TWSIs shall be fixed to prevent the edge from lifting.
Key
1 base plate of the integrated TWSI units
h height of the base plate
a
≤ 3 mm.
Figure 5 — Base plate of integrated TWSI surface and its height
4.5.2 Principles for installation of TWSIs
When used as a system to aid orientation and safety, guiding and attention patterns shall be used in a logical,
sequential manner, with beginning and end points, between which intersections, decision points or hazards
are indicated.
The beginning of a system shall be clearly defined and easy to locate in conjunction with built and natural
guiding elements.
TWSIs may also be used individually to indicate hazards or locations.
4.5.3 Principles for installation of attention patterns
The effective depth and width of attention patterns shall be at least 560 mm.
NOTE 1 An exception to this is railway platforms, where national regulations, standards and guidelines governed by
national legislation take precedence.
When an attention pattern is used to indicate a hazard, it shall have a minimum effective depth of 560 mm.
Greater depth may be needed for safety, particularly when the attention pattern indicates a hazard in the direct
line of travel.
When an attention pattern is used to indicate a hazard, it shall extend the full width of the hazard, from each
direction from which the hazard can be approached, and should be set back a minimum distance of 300 mm
from the hazard.
Where no set-back is provided, a greater depth of the attention pattern should be used to provide greater
certainty of detection and a longer stopping distance.
NOTE 2 The definition of a hazard can vary by situation and by country.
4.5.4 Principles for installation of guiding patterns
When a guiding pattern is used to designate a path of travel, it shall have a minimum effective width of 250 mm.
Where a guiding pattern of TWSIs needs to be detected by a person approaching at an angle, it shall have a
minimum effective width of 550 mm.
A minimum clear path of travel of 600 mm shall be provided on both sides of a guiding pattern.
NOTE For wheelchair users, a clear path of travel of 600 mm is not sufficient. Considerations for wheelchair users
are specified in ISO 21542.
a
h
Annex A
(informative)
Luminance contrast
A.1 Formula for calculating luminance contrast
Different formulae for calculating luminance contrast are used around the world. In this International Standard,
minimum contrast values are given using the Michelson formula. When other formulae are used, the equivalent
minimum contrast values can be determined in order to achieve the perceived visual contrast as required in this
International Standard. Table A.1 shows comparable minimum contrast values for some formulae.
Table A.1 — Comparable minimum values
Sapolinski
Michelson
Weber 125 YY−
()
LRV
()LL−
×100 YY++25
()LL−
12 LRVL− RV
()LL+
×100 12
L
%
%
%
LRV =40 LRV =50 LRV =60 Y = 40 Y = 50 Y =60
1 1 1 1 1 1
Minimum
contrast 30 46 18 23 28 27 28 30
value
Minimum
for discrete 40 57 23 29 34 35 37 39
units
Minimum
50 67 27 33 40 43 45 48
for hazards
NOTE   L is the measured luminance of a surface and Y is the luminance reflectance. Where L appears in a formula, Y can be used
instead. The required minimum contrast for the Sapolinski formula depends on the reflectance of the lighter surface, Y .
Conversion from the Michelson contrast, C , to the Weber contrast, C :
M W
2× C
M
C = (A.1)
W
100+ C
M
where C is the Michelson contrast, on a scale of 1 to 100.
M
Conversion from the Michelson contrast, C , to the Sapolinski contrast, C :
M S
10××LC
1 M
C = (A.2)
S
8×+LC +100
1 M
where C is the Michelson contrast, on a scale of 1 to 100.
M
NOTE 1 Some countries use the LRV method for expressing visual contrast. The recommended visual contrast is
described as the difference in LRV that is equivalent to the CIE Y value of the TWSI and the adjacent surface (LRV - LRV ).
1 2
The instrument required to take LRV measurements is a sphere-type spectrophotometer. The general specification details
are described in Reference [11].
12 © ISO 2012 – All rights reserved

NOTE 2 The Sapolinski formula is a modification of the Michelson formula (see Reference [9]). This formula was
created to secure appropriate contrast values for human eyes for two adjacent darker surfaces.
A.2 Methods for measuring the parameters required to calculate
luminance contrast
A.2.1 General
Luminance contrast can be determined by measuring the luminance of the TWSI and comparing it with
the luminance of the surrounding or adjacent surface, within a width of 100 mm on both sides of the TWSI.
Alternatively, it can be determined by measuring the reflectance of the TWSI and comparing it to the reflectance
of the surrounding or adjacent surface.
Luminance or reflectance can be measured by one of two major methods, depending on the measurement
instruments:
a) contact type, and
b) non-contact type.
All devices should be calibrated to the spectral sensitivity of the human eye, corrected to meet the CIE
photopic curve, V(l).
All TWSI and surrounding or adjacent surfaces should be measured under both wet and dry conditions.
When textured or non-uniform surfaces are being measured, multiple measurements should be made and
averaged. When discrete TWSIs are measured, the field of measurement should include only one TWSI and
no surrounding or adjacent surface.
TWSIs and surrounding or adjacent surfaces should be measured under the type of illumination that is used in
the relevant environment.
It is important to read the instruction manual of any instrument used, and to understand and apply the correct
procedure and method of measurement.
A.2.2 Measurement with non-contact-type instruments
Non-contact-type instruments measure the luminance of a small, defined, surface area from some distance
away from the surface being measured. Non-contact-type instruments are usually fixed onto a tripod stand.
The surface area being measured is determined by the angle of the measurement field of the instrument and
the distance of the instrument from the surface being measured.
Non-contact-type instruments have the following advantages:
— measurements can be taken at the typical angles of perception of people who use TWSIs;
— objects with colour or surface irregularities can be accurately measured, provided that the instrument used
has a measurement field wide enough to include such irregularities.
Non-contact-type instruments have the following disadvantages:
— they require stable ambient light conditions for accurate measurement;
— if luminance, L, is used to determine luminance contrast, they require that the two surfaces to be compared
be measured under the same light conditions.
NOTE Measurement with non-contact-type instruments is described in detail in Reference [9].
A.2.3 Measurement with contact-type instruments
Contact-type instruments are put directly on the surface to be measured. They measure the amount of light
emitted by the instrument itself and reflected from the surface being measured. Since only a small area can be
measured at one time, it is important that multiple measurements be made and averaged, especially when a
surface with irregularities is measured.
All contact-type instruments measure under daylight illumination (CIE D65). Most contact-type instruments can
be set to take measurements under other types of illumination.
Contact-type instruments have the following advantages:
— they are independent from environmental lighting conditions, which allows surfaces that have been
measured independently to be compared;
— they are easy to use.
Contact-type instruments have the following disadvantage:
— they provide somewhat unreliable measurements of objects with surface irregularities.
NOTE An example of this method of measurement is given in Reference [11].
14 © ISO 2012 – All rights reserved

Annex B
(informative)
Examples of installations of TWSIs in specific situations
B.1 General
This annex gives examples of installations of TWSIs in specific situations that comply with this International Standard.
Specific designs are developed country by country, taking into consideration the different physical, climatic
and social situations of each country. National design standards should provide for consistent TWSI systems
within a country.
This annex includes a selection of installation designs that are used in different countries and which have been
adopted in the regulations, standards or guidelines of those countries under national legislation. Other designs
can also comply with the principles and specifications for TWSIs stated in this International Standard.
B.2 Pedestrian crossings
Any TWSI system for pedestrian crossings adopted by a country should be applied consistently throughout
that country.
When used to indicate a pedestrian crossing, attention patterns should be set back 300 mm from the edge of
the sidewalk with a minimum depth of 560 mm, and should be installed perpendicular to the direction of travel
across the crossing (see Figure B.1). Where no set-back is provided, a greater depth of the attention pattern
should be used to provide greater certainty of detection and a longer stopping distance.
A guiding pattern or attention pattern can be used to indicate the location of a pedestrian crossing. A guiding
pattern can also be used to indicate the direction of travel at a pedestrian crossing (see Figure B.1).
TWSIs should be used to help locate the push button control or the tactile walk signal for pedestrian traffic
lights, or both.
When used to indicate a pedestrian crossing that has a pedestrian refuge, attention patterns should also be
provided on the refuge.
Different countries have different designs for installation of TWSIs at pedestrian crossings. Figure B.1 shows
the basic design and elements of the TWSI installation at a pedestrian crossing. Other designs complying with
this International Standard are shown in Figures B.2, B.3, B.4, B.5, B.6, B.7, B.8 and B.9.
b2
2 3
c
b
Key
1 attention pattern
2 location of the stem (installed at the centre of the effective width of the attention pattern, b )
3 location of the stem (installed at the edge of the effective width of attention pattern, b )
4 sidewalk
5 kerb or at-grade kerb
6 vehicular way
7 pedestrian push button
b  effective width of the guiding pattern
b effective width of the attention pattern
p effective depth of the attention pattern
r distance of the set-back from the outer edge of the kerb or at-grade kerb to the edge of attention pattern
a
≥ 560 mm.
b
≥ 300 mm.
c
≥ 550 mm.
NOTE This example shows the basic designs and elements required when installing TWSIs at pedestrian crossings,
based on the principles for installation given in this International Standard.
Figure B.1 — Pedestrian crossing — Example 1
16 © ISO 2012 – All rights reserved
r
ab
p
a
b
a
b
Key
1 attention pattern
2 guiding pattern (used as a stem)
3 sidewalk
4 vehicular way
5 guiding pattern
6 kerbs or at-grade kerbs
p effective depth of the attention pattern
b effective width of the guiding pattern
b effective width of the guiding pattern
r distance of the set-back from the outer edge of the kerb or at-grade kerb to the edge of attention pattern
a
550 mm.
b
560 mm.
c
≥ 300 mm.
d
≥ 250 mm.
NOTE This example combines the use of a guiding pattern along the sidewalk with attention patterns to indicate the
intersection of the guiding pattern leading to the crossing, and the location of the crossing itself.
Figure B.2 — Pedestrian crossing — Example 2
b c
r
b
c
p
r
d
b
p
Key
1 attention pattern
2 at-grade kerb
3 sidewalk
4 vehicular way
5 kerb ramp
p effective depth of the attention pattern
r distance of the set-back from the outer edge of the at-grade kerb
a
560 mm.
b
300 mm.
NOTE This example shows the attention pattern on a kerb ramp set-back from the at-grade kerb, with no stem. When
there is no stem to guide users to a particular location in the width of the crossing, it is important that the attention pattern
extend the full width of the at-grade kerb.
Figure B.3 — Pedestrian crossing — Example 3
18 © ISO 2012 – All rights reserved
ab
p r
Key
1 attention pattern
2 at-grade kerb
3 sidewalk
4 vehicular way
p effective depth of the attention pattern
a
1 200 mm.
NOTE This example shows the attention pattern at a crossing where the vehicular way is raised to the same level as
the pedestrian way. The attention pattern extends the full width of the at-grade kerb, with no set-back. This is important
because a pedestrian who is blind or vision impaired could approach the crossing at an angle and miss the attention
pattern if it is set back, continuing into the vehicular way without realizing.
Figure B.4 — Pedestrian crossing — Example 4
a
p
a
p
b
b
Key
1 attention pattern
2 at-grade kerb
3 sidewalk
4 vehicular way
5 pedestrian push button
6 kerb ramp
b effective width of the attention pattern
p effective depth of the attention pattern
a
800 mm.
b
1 200 mm.
NOTE This example shows the attention pattern, set immediately behind the kerb stone, across the full width of the
at-grade kerb. An attention pattern stem leads to the pedestrian push button and the crossing point.
Figure B.5 — Pedestrian crossing — Example 5
20 © ISO 2012 – All rights reserved
a
p
b
b
c
b
5 4
c
b
b
b
Key
1 attention pattern
2 guiding pattern (used as a stem)
3 kerb ramp
4 at-grade kerbs
5 kerbs
6 sidewalk
7 vehicular way
8 pedestrian refuge
p effective depth of the attention pattern
b effective width of the guiding pattern
b width of the kerb ramps
a
560 mm.
b
550 mm.
c
900 to 1 000 mm.
NOTE This example shows the attention pattern, set immediately behind a 50-mm-high kerb. It extends across the full
width of the crossing except for the section covered by a 900 mm to 1 000 mm kerb ramp, ending at-grade. A stem of
guiding pattern leads to the side of the attention pattern farthest from the kerb ramp. The guiding pattern also leads to the
push button control.
Figure B.6 — Pedestrian crossing — Example 6
a
a
p
p
Key
1 attention pattern
2 pedestrian refuge
p effective depth of the attention pattern
p depth of the kerbs or at-grade kerbs (dimension only applicable if kerb is wide enough)
p depth of the pedestrian refuge
a
800 mm.
b
150 mm.
c
> 2 000 mm.
NOTE This example shows the attention pattern at both sides of a wide pedestrian refuge that is cut through to be
accessible to a user. In this example, the attention pattern is 800 mm deep, and set immediately behind the kerb stones.
The attention pattern alerts blind or vision-impaired pedestrians when they enter and when they are about to leave the
refuge. The same arrangement can be used where the wide refuge has kerb ramps.
Figure B.7 — Pedestrian crossing — Example 7
Key
1 attention pattern
2 pedestrian refuge
p effective depth of the attention pattern
p depth of the kerbs or at-grade kerbs (dimension only applicable if kerb is wide enough)
p depth of the pedestrian refuge
a
p - 300 mm.
b
150 mm.
c
< 2 000 mm.
NOTE This example shows the attention pattern at a narrow pedestrian refuge (<2 000 mm) that is cut through. The
attention pattern covers the
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