Summary This paper complements the data presented in phase I of this study. This paper looks at
three new escape lighting systems, and compares them with three systems tested previously. In
addition to testing their suitability for 30 people with different visual impairments, results are
presented for 12 normally sighted people. Using the facilities at the Building Research Establishment,
it has been possible to examine the performance of ceiling-mounted emergency luminaires providing
two levels of illuminance, LED strips in two configurations, LED strips with overhead luminaires and
miniature incandescent wayfinding strips. Speeds of movement are presented here, along with
subjective responses. Comparisons are made with findings from normally sighted people. There are no
significant differences in the walking speeds under the lighting systems, but the visually impaired
subjects had significantly differentopinions on the ease with which they could see where to go.
Emergency lighting and wayfinding provision systems for visually
impaired people: Phase II of a study
G K Cook† BSc PhD, M S Wfiot† BSc PhD, G M B Webber‡§ BSc PhD and K T Bright† MSc
†University of Reading RG6 6AW, UK
‡BRE, Garston, Watford, Herts. WD27JR, UK
§Consultant, Bricket Wood, St. Albans.
List of symbols
2
I
L
The test facility at BRE is as described in the previous paper(’).
Six lighting systems were tested, as follows.
Miniature incandescent wayfinding system
LED wayfinding system
L2 LED wayfinding system variant 2
LO LED wayfinding system with overhead emergency lighting
0 Basic overhead emergency lighting
02 Enhanced overhead emergency lighting
1
Introduction
Following our previous papery which answered general questions about the suitability of wayfinding systems and highmounted emergency luminaires for visually impaired people,
it was decided that there was a need to look at specific design
details of lighting systems. This was prompted by some of the
conclusions from phase I, particularly that visually impaired
people found it easier to see where to go under the three
powered wayfinding than under the basic highmounted emergency luminaire system that slightly exceeded
the illuminance recommendations of British Standard
BS5266(l). One issue we wanted to address was whether significanuy increasing the light output of the overhead emergency
lighting system would significantly improve visually impaired
people’s opinion of the traditionally high-mounted luminaires. We also wanted to investigate different design attributes of a powered wayfinding to see how important
some design are to people’s In addition we
needed to assess the effect combining wayfinding systems
and British Standard emergency lighting on the performance
of visually impaired subjects.
This paper presents of a study carried out by the
University of Reading in collaboration with the Building
Research Establishment (BRE) using the BRE facility. This
paper details the from the second set of 30 visually
impaired people, looking at six lighting systems: three
common to tested in phase I, and three new
systems. This describes the experimental facility, the
procedure and the characteristics of the volunteers. The findings are presented for visually impaired and normally sighted
volunteers, and the conclusions of the study are discussed.
Experimental facility
21
jBaMc oc~~K~ ~M~giMcy %~~ (Q)
This system consisted of five 4 W fluorescent luminaires
mounted on the ceiling, and one high on the wall at the
bottom of the stair. There was a fluorescent pictogram exit
sign (160 mm in height, BS5499 Part 1 format<3), luminance
935 cd m-2) on the mock exit door, at a height of about
1800 mm. This system was the as phase I, but with new
lamps that increased the illuminances by about 40%.
2.2 LED wayfinding ~~M (L)
Identical to that in phase I, this system consisted of upwarddirected LEDs providing a line of markers along the route, and
downward directed LEDs to illuminate the floor.
2.3 Miniature MesM&K~Kt
nM~M~ system (1)
This was identical to that in phase I.
2.4
JEMMMc~
(02~
This system consisted of five 8 W fluorescent luminaires
mounted on the and one high on the wall at the
of the stair. same exit was used as with emergency lighting system 0.
2.5 LED wayfinding Vst--m ’Daritmt 2 (L2)
The full LED system, L, was modified to the provision of upward- and downward-directed LED strips on one
side of the long straight corridor compared to both sides. A
second modification was to exclude the LEDs in the nosings of
the stair. Elsewhere the L2 system was the same as L,
including the directional arrows on both sides of the corridor.
The sign on the exit door was the LED pictogram (at height
1380 mm, size 80 mm high) consisting of LEDs developing
140 mcd.
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43
Table 1
Mean horizontal illuminance (lu~) on the floor at the centre line along the escape route
LEDzvqyfihdilqwsum zvimwomdmneqa*yIi#hGng (LO)
The LED system variant 2, L2, was modified to investigate the
combination of marker LEDs (excluding illuminator LEDs)
with high-mounted emergency lighting to illuminate the
floor. In the long corridor the marker LEDs were provided
only on one side, elsewhere the marker LEDs were on both
2.6
sides of the route.
The mean illuminances along the route are shown in Table 1.
3
the chart for phase I, or 2.65 Ix for the re-lamped 11.
The second test was under normal lighting, with a mean illuminance of 92.1 Ix on the chart. The rationale behind
allowing the volunteer to get as close to the chart as 1 m,
compared to the conventional 6 m used by optometrists, is
that in a building people would move as clc~s~ as possible to
read a sign that was unclear if they thought it contained useful
information. The cumulative percentages of subjects who
could read an entire line are plotted against the visual angle
subtended by the height of the letter in Figure 1, for both sets
on
Experimental procedure
The experimental procedure was identical to that described in
phase I.
Thirty subjects with visual impairments carried out the tests.
There were 14 men and 16 women, of average age 53.2 years,
with a range of 36-73 years. There was only one person older
than 66 years, and she was not noticeably slower than the
other subjects. Ten people used a white cane; one of these had
a long cane. A simple vision test using a Snellen chart was
carried out under lighting conditions that provided
vertical illuminance of 92lx. It was found that 12 of the 30
volunteers had vision worse than 3/60. Six people had tunnel
vision, five had peripheral vision and three people had
sporadic vision. The of eye conditions exhibited by
these 30 volunteers was wider than for phase I, with more
of multiple eye problems. People with macular degeneration formed the largest group, with seven of the volunteers
having this eye condition; two of them also had other complications. The volunteers also had glaucoma, retinitis pigmenrosa, cataracts, optic nerve damage, detached retina as well as
other eye conditions. Of the 30 people, 23 were registered
blind, six were partially sighted (one of whom could
be registered blind), and there was one person who could
legally be registered partially sighted.
Comparing the volunteers from n with those in phase
I, there are two main attributes to look at - age and visual
acuity. The mean age of the participants for phase II is 53.2
compared to 51.6 for phase this is not a significant difference under a t-tesL are different gender mixes
in the two groups, but not radically so (18 men in phase 1,14
for phase W. The noticeable difference is that 18 people
used a cane in phase I, but only 10 in n. When comparare using the data from the vision the results
are different. Two vision tests carried out, using different
Snellen visual acuity charts. The volunteer stood at 1.5 m to
read the chart; a successful letter acuity was achieved if all the
letters on a line were correctly read After the line with the
letters had been read, the volunteer was allowed to
stand at 1 m to see which line could be completed at that
distance. The volunteer was allowed 3 minutes to complete
this test. The first eye test was carried out under the British
Standard emergency lighting system (0) with 1.43 Ix incident
44
1 The relationship between the cumulative percentage of subjects
who could read an entire line of a Sndlen chart and the angle subtended at
the eye by the height of a letter on that line. The top figure presents results
measured under emergency lighting (1.43 or 2.65 Ix on chart), the lower figure
presents results measured under normal lighting (92.1 Ix on chart).
Figure
Downloaded from lrt.sagepub.com by JC CONCEPCION on May 14, 2015
of volunteers. It can be seen that people from phase I had, on
average, worse visual acuity than those from phase n. This is
also shown by the fact that five (eleven) people could read the
top line of the chart under normal (emergency) lighting in
phase I compared to one (two) people from phase U. The top
letter on the chart is 87 mm in height, and subtends an angle
of 5° at a distance of 1 m. Because there are no data for the
visual angle that people can see, it is impossible to carry
out t-tests to compare the two groups. However, when
carrying out a rank sum test (the Wilcoxon-Mann-Whitney
tesd4», the visual acuity of the people from the two groups is
found to be significantly ~nt. ~ II people have better
visual acuity than phase I people, with p < 0.025 for emer0.05 for normal
gency lighting illuminating the chart, andp <
lighting.
Results from 12 normally sighted people are included in this
paper. These sighted subjects were 4 men and 8 women, of
average age 51.25 years, with a range of 42-61 years, which is
not significantly t from the age of the visually
impaired volunteers. The results of the vision tests for the
normally sighted subjects are also plotted in Figure 1, down
to the minimum angle of letter height that was measured,
0.28°.
4
Findings
The results that are presented here come from two sources.
The objective results are speeds that are calculated from times
taken froan video recordings from the low-light-sensitive
cameras. The subjective analysis comes from the answers to
the questionnaire, which is described in Section 4.3. Throughout the following sections, the lighting systems are referred to
by the code letter used in the headings in Section 2.
The statistical tests that were carried out to compare the
results from different lighting conditions depended on
whether the data was normal or skewed. Whenever the data
sets that being compared were skew, non-parametric tests
were carried out. For skew pair comparisons, a sum test,
the ’~i.lcc~~c~ir-.t~fann ’tn~ tesf4), was performed instead
of the more usual parametric ~-t~t. The results of the tests are
reported up to significance levels of 0.05. Further statistical
tests were carried out - for non-skewed data the .~ te.st, and for
skewed data the Kruskal-Wallis one-way analysis of variance
by ranks test’4) - to ensure that the multiple t-tests were not
including insignificant results. Results are presented when the
relevant tests suggest that there are differences between
the data sets at a significance better than 0.05.
4.1
speeds measured for the different lighting systems
shown in Figure 2. These are shown for three sections of
The mean
are
the route:
-
-
-
Getting up from the chair to leave the office ~o~ce
outward)
Start of the landing to the bottom of the stair (stairway
outward)
From the bottom of the stair
to
the mock exit door
(corridor outward)
The speeds were also measured when
the subject returned.
These sections are identical to those included in phase 1. None
of the speed data sets was skewed in phase l3, so parametric
tests could be carried out.
o~ctwctrd and office return
As can be seen in Figure 2, the slowest part of the route is
leaving the o~ce, as was found for phase I. Again this might
not be a function of the lighting systems, merely the effect of
the sudden change from 400 Ix to an illuminance in the range
£D.7~-6.5 l~ disabling peoples eyes. The claim that it is not the
particular lighting system that is at fault, but the sudden
reduction in illuminance, is confirmed by only six of the 208
runs being slower returning through the office than leaving it,
,
and that 47.6% of the runs are at least twice as fst on
returning in the office. This occurs despite the fact that people
are heading into a relatively dark room, instead of heading to
an illuminated doorway. It is interesting that these results are
similar to those from phase I, despite the range of eye conditions being very different.
The F-test showed no significant differences between the
speeds for the lighting conditions, either outward or return.
On carrying out a one-tailed related t-test to compare the
speeds in the o~ce on the outward and return parts of
the route, it is clear that the subjects are quicker when
returning (p < 0.0005 for all lighting conditions), when they
know the route. However, it is not just a route learning
process, as the above results are found if only runs 4 to 7 are
examined. At this stage the test subjects ought to be familiar
Speed ~, f e~r in different sections off ~r~e
speeds are calculated from all completed runs. If any
incomplete, the data from the whole run were
ignored. Findings for the visually impaired suhj are
presented for 208 completed runs; there were two incomplete
runs by two subjects involving 0 on both occasions. In both
the incomplete runs occurred the first time the volunteers attempted the route, and because the volunteers thoughtt
they had finished the route and returned before they had
reached the mock exit door. As mentioned earlier(’)., this is
unlikely to happen in a real situation where there is likely to
be less ambiguity about what constitutes the end of the escape
route, as this will generally be outside the building. Obviously,
in a real-world situation people would not return along an
escape route, once having reached the (supposed) exit door,
but would use it to leave the building.
Mean
runs was
2 A graph of mean walking speeds of people who are visually
impaired passing through different parts of an escape route under six different
lighting conditions: 0, basic overhead emergency lighting; U LED wayfinding system; I, incandescent wayfinding system; 02:, enhanced overhead
emergency lighting; L2, LED wayfinding system variant 2; LO, LED
wayfinding system with basic overhead emergency lighting.
Figure
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45
with the route, which indicates how slowly visually impaired
people start this route, even when they have completed the
route three times.
Stairway ~ru~d and st~ir~ay r and ~~midar ~~c~rd and
corridor return
The F.test showed no significant differences between the
speeds for the lighting conditions, either outward or return.
4.2 Comparisons of arr~urznce with
volunteers
ta
normally sighted
collected from 12 normally sighted people in the
way as for the 30 visually impaired volunteers. The
lighting systems are identical for the two groups. As for phase
I, the comparison between normally and visually impaired
people is achieved by finding the ratio of the mean speeds in
t parts of the route; this is shown in Table 2.
were
same
Generally, the visually impaired subjects walk at 0.54 to 0.86
the rate of a normally sighted person; this compares with 0.43
to 0.87 from phase I. The faster relative speeds on the stair that
occurred in phase I did not happen in phase II. When unrelated t-tests were carried out to compare normally sighted
people and visually impaired people on all sections of the
route for all lighting conditions, it was found that the
normally sighted walk significantly faster, with a significance
of, at worst, p < 0.05. However, there were only five occasion
out of the 60 comparisons when the significance was worse
than 0.005, twice for L (stairs out and corridor return,
p < 0.01), twice for 02 (corridor return, p < 0.05, and stair
return,p < 0.025) and once for LO (corridor return,.? < 0.01).
Two measures are used to compare the lighting systems. First,
if the number of times that the speeds on the ten parts of the
route are not as significantly different as < 0.0005 is counted,
it is found that the system with the highest score, 6 times out
of a possible 10, is for 02. The next system that causes the
visually impaired subjects’ walking speeds to be less significantly different to normally sighted speeds is L, with four
parts of the route being not as significant as < 0.0005. Another
way of assessing which lighting system helps visually
impaired people die best in comparison to normally sighted
people is to count the number of times that a ~ght~ng system
has the highest ratio in Table 2 for er~nt parts of the route.
There are only two lighting systems that have the highest
ratio: 02, seven times, and L, three times. These findings
suggest that these two help visually impaired people
to a greater extent in comparison to normally sighted people.
It should be remembered that there are no significant differences in the mean walking speeds under any of the lighting
conditions for the visually impaired volunteers.
Referring again to the ratios in Table 2, there are two parts of
the route where visually impaired people perform relatively
badly in comparison with normally sighted volunteers. As in
phase I, the landing outwards part of the route causes visually
impaired people to slow down more than on other parts of the
route; this is true for all lighting conditions and may indicate
the problems in identifying the top of the stair when the eye
is still undergoing changes in dark adaptation. The other part
of the route that causes problems is returning into the c~~.c~,
which is the worst for all lighting systems on die return part
of the journey.
43
~’z~rj~c ° responses
As for phase I, two questions on di~culty were asked The
questions were asked and responded to orally: they were
How difficult did you find it to see where you were going on
.1..;>
the stair?
How difficult did you it to see where you were going in
the ~~~
with a response on a seven-point scale: 1
cult.
=
very easy, 7
=
very
Some of the responses to these questions were skewed. The
non-normality of the data is due to people having limits to
their choice, so for systems that score averages close to the top
or bottom limit the distributions cannot be symmetrical.
Rank sum and Kruskal- W allis tests were therefore used for
these comparisons. Results for both questions were shown to
have significant differences between lighting conditions when
tested using die Kruskal-Wallis metric.
The mean scores for culty on the stair, against the mean
illuminances on the stair, are shown in Figure 3. Lower scores,
below 4, indicate the lighting system made it easier for people
to see where they were going; the error bars indicate the
standard error. Figure 3 shows that the visually impaired volunteers thought it hardest to see where they were going using
lighting system 0; it is significantly worse than four of the
other systems, with significances ofp < 0.0005 for 02 and LO,
p < 0.005 for L, ~.nd~ < 0.025 for L2. The next highest mean
score is for I and is significantly worse than three of the other
systems, 02 (p < 0.0005), LO (~ ~ 0.005) and L (p < 0.01).
The third highest (and so fourth best of six) is L2, which is
Table 2 The mean ~~r visually impaired subjects divided by that for
no y ’ t~d subjects, for different lighting syss
Figure 3 The relationship between the mean degree of difficulty of seeing
where to go against mean illuminances on the stair for the six lighting condi1ions. The error bars show the standard error.
46
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Table 3 Mean scores of the answers to ’How uncomfortable did you find
the brightness of the lighting system?*, 1 = uncomfortably dim, 7 uncomfortably bright, for visually im and normally sighted volunteers. Final
column shows the mean illuminances along the entire escape route
significantly worse than 02 (p < 0.005), LO (p < 0.025) and L
~p ~ 0.05). Hence, the basic British Standard overhead emergency lighting system, 0, is regarded as making it significantly
=
more difficult to see where to go than four of the other five syswhether the systems are regarded
tems tested. When
easier or mare ’ cult in
as being
where to
assessing
significantly
seeing
go than a neutral score of 4, the results are that L, 02 and LO
are d~~nitel~ ~ier ~ ~ 0.0005), as is L2 (p <
0.005). The
differences in the
scores
for the stair between L and L2 is
significant at p < 0.05, which seems to indicate that the six
in the stair nosings are preferred to some extent. When
comparing systems L2 and LO, the system with the overhead
lighting (LO) is pr~f d, even though there is less iii
nance on the treads of die stairs. System 02 scores significantly
lower than 0, indicating the visually impaired subjects preferred the increased light from the enhanced emergency luminaries, even if there is no significant difference in mean
walking speeds. The minimum illuminances along the stair
are
system O. The minimum illuminances along this part of the
mute are 2.92 lx and 0.73 Ix, respectively.
The subjects were also asked about the brightness of the
systems; they were asked
Hozv r~r~c~mfi~bl~ did you find the brig of the lighting
3.93 Ix for 02 and 1.08 Ix for 0.
system?
with a response
The findings for the mean scores for difficulty in the corridor
are shown in Figure 4, plotted against the mean illuminance
in the long corridor. As for the stair, system 0 scores highest
(worst), and is significantly worse than 02 (p < 0.0005), and
LO and L (p < 0.005). System L2 scores significantly worse
than 4~2 ~r ~ 0.005), LO (p < 0.025) and L (p < 0.05). System
I also scores significantly more difficult in seeing where to go
than do ~2 ~ ~ 0.01), LQ ~p ~ 0.025) and L (p < 0.05). Tests
of whether the mean scores sign~ t1y erent from a
neutral score of 4 show t systems L, 02 and LO are definitely easier (p < 0.0005); as for the stair, I is now easier
(p < 0.005), as is L2 (p < 0.01).
seven-point scale: 1 uncomfortably
dim,
uncomfortably bright. The mean scores are
presented in Table 3, along with the mean illuminances along
the route. For the visually impaired, none of the mean scores
is above 4, which is the ’happy medium* score, neither too dim
nor too bright for ~or~c~rt. For the visually impaired subjects,
7
Kruskal- W allis test indicates that there are significant
erences between the scores for erent lighting conditions. Four of the systems have a mean score that is significantly lower than 4 (0 and I, p < 0.0005; L2, p < 0.005; and
LO, p < 0.025), so these systems are regarded as more dim
than is comfortable. Comparing the ~r~nt lighting systems,
system 0 is regarded as significantly dim compared to all
other systems (p < 0.0005, apart ~m I for which ,p < 0.025).
The system that is ranked as being the next dim (although it
has a mean illuminance less than 0) is I, and this is significantly er~nt from L (p < 0.01), 02 (p < 0.025) and LO
(p < 0.05). The only other system that is regarded as t
is L2, which scores significantly lower dm L (p <
0.05).
These results indicate that L is reported as the least dim
system (closest to 4), despite having a mean illuminance along
the centre line of the floor less than half that of 02. It should
be noted that this system, along with most other wayfinding
provision systems, produces light near floor level that is
directed up towards the eye, so the measure of its illuminance
along the centre line of the escape path on the floor may not
be the best measure of the brightness perceived by the eye.
’1
4.4 * vtr~ crf
~~~r~~
Figure 4 The relationship between the mean degree of difficulty of seeing
where to go against mean illuminance in the long corridor for the six lighting
conditions. The error bars show the standard error
=
a
In the long corridor system, L2 had marker and illuminator
LED tracks on one side of the corridor only, while system LO
had a marker track on one side together with the basic overhead emergency lighting system 0. System L had marker and
illuminator LED tracks on both sides of the corridor. The
lighting arrangements presented by systems LO and L are
preferred to that of system L2. In part, the preferences towards
systems LO and L may be attributable to their higher mean
illuminances on the floor, 2.19 Ix and 0.91 Ix, respectively,
compared to system L2, 0.69 bL
The increased illumination from the enhanced emergency
luminaires, 02, is preferred to the basic British Standard
on a
=
*~e responses with normally sighted
When comparing the results of the visually impaired volunwith those of 12 normally sighted people, it is found,
surprisingly, t there are no significant differences between
the mean scores by the n groups for five of the six
lighting conditions. The only lighting system that has better
scores from the normally sighted volunteers than from the
visually impaired group is L2. For the stair, the significance
isp < 0.005: for the corridor it is p < 0.025. This is in contrastt
to the results from phase I, where systems L and 0 are scored
worse by the visually impaired subjects. This seems to indicate that the scoring its not absolute, but relative.
Coinddentally, when F-tests are carried out, the result is that
there are no significant erences between the scores given
to the six lighting conditions by the 12 normally sighted
people. This seems to indicate that normally sighted people
are less demanding in their requirements for emergency
lighting systems than are visually impaired people.
Downloaded from lrt.sagepub.com by JC CONCEPCION on May 14, 2015
47
For the question about the brightness of the systems, as for the
visually impaired, none of the mean scores for the differentt
lighting systems was above 4. The mean scores of the
normally sighted people are presented in Table 3. When
making comparisons with the data from the visually impaired
subjects, there are no statistically significant differences
between the mean scores. The rank order of the lighting
systems is the same for the two groups, with the one slight
~ that 02 and LO are given the same mean score by
the normally sighted group. It should not be surprising that
the subjective brightness rank order of the systems is
unchanged between the two groups; what is perhaps
surprising is the similarity of the mean scores.
When the data from the normally sighted group are tested
using an F-test, there is no suggestion of significant differences between the scores of the lighting systems. There are
four systems that score significantly less than 4, indicating
they are too dim for comfort. These systems are 0 (,~ < 0.005),
I and L2 (p < 0.01) and 02 (p < 0.025).
4.5 Comparisons cr~’
~lun
~ ,~ with phase I visually impaired
Comparisons with
normal lighting are a useful measure of
how successful emergency lighting is: if there is no significant
difference, the lighting system is thought to be as good as
possible. ~nsequ~ntl~, it was hoped that the results frum
phase I could be used. To see whether this is possible, it is
necessary to check that the volunteers ~m phase I and phase
II are directly comparable. It is seen from Section 3 that there
are differences in visual capabilities and cane use between the
two groups of people who carried out phase I and phase II of
this study. However, appropriate pair comparison tests
between the data frorn phase I and n revealed that there are
no significant differences in the speeds for the o~ce, stairway
or corridor parts of the route for the three systems (0, L, I) in
common in phases I and II.
’
If the subjective views for the three questions in section 4.3 are
compared, there are no significant differences for 0 or L, but
for the miniature incandescent system two of the questions are
scored significantly better for phase I than for phase I~l. The
~ty of seeing where to go on the stair is scored dfferendy
(p < 0.025), as is the uncomfonableness due to the brightness
of the system (p < 0.005). The differences in subj we scores
also mean that comparisons with absolute values (for example,
the neutral position of 4) are dif5erenL- It is to be noted that
although people who were tested in phase I had worse visual
acuity than those of phase H, they scored one system better.
Although the difference between the two phases are small,
there are some between the two g when
comparisons are drawn between the lighting conditions. For
this
it was decided not to compare iigltting systems
between phases, as my possible differences could be
to using a group of 30 people father than to innate
differences in the lighting systems.
5
Condusions
The
subjective results for phase II indicate that visually
impaired people find that traditional basic emergency luminaires do not make it as easy to see where they are going as do
the brighter overhead (enhanced) emergency luminaires, or as
is the
case
with
a
combination system of marker track
wayfinding provision and basic emergency luminaries, or a
~ waynnding system with marker and illuminator
s. This finding is similar to those when when a ia
incandescent wayfinding system is compared with the same
three systems, although with less significant differences. A
conclusion is that visually impaired people prefer an enhanced
overhead lighting system that produces a minimum of 2.5 Ix
the level parts of the route and 3.9 Ix on the stair, to a basic
system that has a minimum of 0.73 Ix on the level parts of the
route and 1.1 Ix on the stair. They also prefer the full LED
wayfinding system to the basic overhead emergency lighting.
Adding a low-mounted track of upward-pointing LEDs to this
basic emergency lighting system is seen as an improvement.
It is found there is a slight pr~f’er~nce (at a significance of
p ~ 0.05) for the LEDs in the nosings of the stair. There is a
slight preference for the light tracks on both sides of an escape
path compared to on one side only (at a significancep < 0.05).
The LED wayfinding system with upward-pointing markers
combined with overhead emergency lighting is preferred to
the LED wayfinding system with upward-pointing markers
and downward-pointing illuminators. A BRE Information
for recommendations on erPaper has been published<5>
and
gency lighting
wayguidance provision four people with
impaired vision based on this research.
on
The walking speeds of visually impaired people under
powered emergency escape route lighting conditions are
generally about 55-85% of the speed of the normally sighted.
The higher illuminance produced by the enhanced overhead
emergency lighting system gave greater assistance to the visually impaired than to the normally sighted people. Both the
normally sighted and visually impaired subjects placed the
basic overhead lighting system last in terms of their subjective
opinions.
Acknowledgements
’
This work has been funded by the
Sciences Research Council.
Engineering and Physical
References
1
2
3
4
The mean walking speeds that visually impaired people
achieve under different powered emergency lighting condi-
48
tions have been shown to be generally very similar, as reported
in phase I.
5
Wright M S. Cook G K and Webber G M B Emergency lighting and
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