GRE 48 - Informal 30
`
`Informal Document No. 30
`(48th GRE, 9-12 April) 2002
` (Agenda Items 1.2 and 4.2)
`
`History and
`Scientific
`Back-up
`
`Hanno Westermann
`(AFS Secretary)
`
`references:
`TRANS/WP.29/GRE/2002/18 to 20
`
`HW - April 30, 2002 - AFS/GRE/Back-up.PDF - 21 pages
`
`VWGoA EX1015
`U.S. Patent No. 11,208,029
`
`

`

`GRE 48 - Informal 30
`
`Content
`
`page
`
`1.
`
`The AFS Project
` 3
`- Project history and desirability of headlighting improvements
` 6
`2. Glare and Visibility under night time traffic conditions
` 6
`2.1
`Glare from headlamps on traffic roads
` 7
`2.2
`Influence of lateral distance of glare sources on glare
`2.3
`Disability glare and visibility of pedestrians on straight traffic roads 9
`2.4
`Influence of the light emitting area on discomfort glare
`11
`2.5 Glare from headlamp reflexes on wet roads 12
`2.6
`Influence of vehicle inclination changes on glare
`14
`2.6.1 .. due to vehicle loading
`14
`2.6.2 .. due to vehicle dynamics
`15
`Glare reduction and visibility improvement on illuminated roads
`16
`2.7
`Glare reduction and visibility improvement in curves
`18
`2.8
`Photometric Requirements
`3.1
`Co-ordinates for headlamp photometry
`3.2
`Specified values in the photometric tables
`Vehicle appearance at night
`
`3.
`
`4.
`
`19
`19
`21
`
`HW - April 30, 2002 - AFS/GRE/Back-up.PDF page 2
`
`

`

`GRE 48 - Informal 30
`
`1. The AFS Project
`- Project history and desirability of vehicle front lighting improvements
`During the development within the Eureka project "VEDILIS" (Gas Discharge Light Sources)
`it became obvious that a single passing beam pattern can not provide an optimum lighting
`performance for all common road situations, particularly not in adverse weather conditions; it
`had to be a compromise. Already back in the 60th (see figure), attempts were made for
`adaptive beams, but the projects were stopped for missing technologies with respect to
`accuracies of light sources and reproduceability of mechanical levelling movements. However,
`headlamp levelling control was introduced in the 70th, be it by manual setting as a first step.
`
`M u l t i p l e U s e b y O v e r l a y
`F i r s t S t e p i n E u r o p e a n H a l o g e n D e v e l o p m e n t
`
`P H I L I P S
`
` 1 9 6 2
`
`( P H I L I P S R e s e a r c h R e v i e w 1 9 6 2 )
`
`F l a s h t o P a s s
`
`M a i n B e a m
`
`F o g a n d T o w n B e a m
`
`" P a s s i n g B e a m s "
`
`D i p p e d B e a m
`
`( C o u n t r y R o a d s )
`
` J.J. Balder, Iodine incandescent lamps, Philips Technical Review, Vol 23, No.8/9, 1961/2
`In 1992, new technologies were available that would allow front lighting systems to adapt in
`lighting performance for different road and weather conditions. The partners of the VEDILIS
`project therefore decided to initiate a new EUREKA project "AFS" with the purpose to
`advance in the development of adaptive front lighting systems and overcome some major
`weaknesses of conventional passing beams.
`In May 1993 the Eureka project status was granted. A value analysis and feasibility study of
`shortcomings of conventional front lighting revealed possibilities to improve visibility and
`comfort for typically adverse conditions. The consortium in the project was build from light
`source manufacturers, headlamp manufacturers and car makers from over the world.
`
`3 LIGHT SOURCE
`M A N U F A C T U R E R S
`
`OSRAMOSRAM
`
`PHILIPSPHILIPS
`
`GE-lightingGE-lighting
`
`G B
`
`F
`
`USA
`
`1 0 L I G H T I N G D E V I C E
`M A N U F A C T U R E R S
`
`A U T O M O T I V E L I G H T I N GA U T O M O T I V E L I G H T I N G
`
`GUIDE-Corp.GUIDE-Corp.
`
`HELLAHELLA
`
`I C H I K O HI C H I K O H
`
`KOITOKOITO
`
`VALÉOVALÉO
`
`SAMLIPSAMLIP
`
`STANLEYSTANLEY
`
`VISTEONVISTEON
`ZKWZKW
`
`S
`
`E U
`
`N L
`
`D
`
`CR
`A U
`
`I
`
`-
`
`JAPAN
`
`KOREA
`
`9 V E H I C L E
`MANUFACTURERS
`BMWBMW
`FIATFIAT
`
`DAIMLER-CHRYSLERDAIMLER-CHRYSLER
`
`GM-OPELGM-OPEL
`
`PEUGEOTPEUGEOT
`
`RENAULTRENAULT
`
`SAABSAAB
`
`VOLVO-carsVOLVO-cars
`
`VW/AUDIVW/AUDI
`
`HW - April 30, 2002 - AFS/GRE/Back-up.PDF page 3
`
`

`

`GRE 48 - Informal 30
`
`The project structure was set up and work could begin.
`
`A F S P R O J E C T O R G A N I S A T I O N
`
`A F S D I R E C T O R A T E
`
`S t e a r i n g B o a r d
`S t r a t e g y C o n t r a c t s F i n a n c e s
`
`P r o p o s a l s
`
`S E C T R E T A R Y
`
`W o r k i n g G r o u p
`
`T e c h n i c a l M a n a g e m e n t
`R es e a r c h C o n t r a c t s
`
`T a s k G r o u p
`
`T a s k G r o u p
`
`T a s k G r o u p
`
`R E G U L A T I O N
`
`F I E L D T E S T S
`
`R E S E A R C H
`
`L T I K
`
`U T A C
`
`T U - D A
`
`T U - D A
`
`T N O
`H F R I
`
`K E M A
`
`I E N G F
`
`First a marketing study was made to investigate the drivers' complaints and their wishes.
`Enquired for the wishfulness and priority of different options, the drivers in all age groups,
`female and male, wearing and not wearing glasses understood easily their advantage with an
`improvement for wet road lighting (W), improved passing beams (C) and bend lighting (B).
`For the latter a cost increase such as being paid for front fog lamps or even ABS was judged
`acceptable. The special visual conditions on town roads with public lighting (V), on motorways
`(E) and for overhead signs (O) found less understanding and were, accordingly, judged of
`lesser value.
`
`M a r k e t i n g R e s e a r c h i n D , F , I a n d S
`A n a l y s i s o f P r e f e r e n c e a n d U n d e r s t a n d i n g
`
`S T R O N G P R I O R I T Y W E A K
`
`1 0
`
` 8
`
` 6
`
`V
`
`1 2 3 4 5 6
`
` 4
`
` 2
`
` 0
`
`F R E Q U E N C Y
`
`S TRONG PRIORITY WEAK
`
`D r i v e r R e s p o n s
`
`W
`
`R a n k i n g o f t h e 6 F u n c t i o n s
`
` W B C E O V
`
`A c c o r d i n g t o t h e i r P r i o r i t y
`
`1 2 3 4 5 6
`
`H I G H V A L U E
`C O N C E P T S
`PRIORITY
`
`E X A M P L E S
`
`UNDERSTANDING
`
`W C
`
`3 0
`
`B
`
`2 0
`
`1 2 3 4 5 6
`
`10
`
` 8
`
` 6
`
` 4
`
` 2
`
` 0
`
`F R E Q U E N C Y
`
`1 0
`
`0
`
`V
`EO
`
`LESSER VALUE
`C O N C E P T S
`
`The results of the marketing study gave evidence to pursue the project and to allocate
`financial assets for the project. After more detail work in function development, the necessary
`research was specified and first prototype systems were made for field tests and to develop
`type approval procedures. The specified research included dynamic glare and the influence
`of shape, area and partition of the headlamps on glare as well as on vehicle appearance for
`other road users. Initially it was also planned to include road reflection research on dry and
`wet roads in different countries as well as statistical research on pedestrian reflection and on
`the statistical positions relative to the headlamps of targets such as road signs, pedestrians,
`rear view mirrors in the visual field.
`
`HW - April 30, 2002 - AFS/GRE/Back-up.PDF page 4
`
`

`

`GRE 48 - Informal 30
`
`The enormous cost involvement of such research and development (8 M €) was reason to
`apply for sponsorship within the framework of BRITE EuRam III - with 20 partners and 7
`research institutes being involved. However, the application was denied and preference given
`to non automotive traffic projects. This was a loss of a year and urged to cut the research
`activities to a bearable budget. The research was dedicated to glare and appearance issues
`only and to the assistance of test houses in developing type approval procedures and the set
`up and evaluation of field tests.
`The AFS systems were developed and designed to adapt the front lighting performance to
`particular environmental and traffic conditions. Such particularly differing conditions prevail on
`motorways, country and town roads and they prevail also in adverse weather such as fog,
`precipitation, wet roads and when driving on curved roads or cornering. For the special
`conditions in fog and cornering, special lamps are specified and regulated with adequate
`performances. They can be reciprocally incorporated in AFS systems. Their lighting
`performances, however, form no part of the AFS system requirements but of separate ECE
`Regulations.
`The project targets (phase II) were finalised by May 1999. The results were presented and
`real scale test drives done at the Balocco test grounds by members of the participating
`industries and invited guests from national governments, GTB and GRE.
`
`AFS Project Development
`Activities and Cost
`
`M A Y
`
`PHASE I I
`
`PHASE III
`
`2 0 0 2
`
`-....
`
`DRAFTING
`
`SS U R E K A - S t a t u s
`
`P r o j e c t N o . 1 4 0 3
`
`2 7 o f
`
`M A Y
`
`PHASE I
`
`Presentation
`
`REGULATIONS
`
`Verification
`
`B a s i c R e s e a r c h
`
`---> GTB ----> GRE
`
`E x p e n d i t u r e s
`
`M ECU
`
`-~
`-~
`
`3
`
`2
`
`1
`
`-~
`
`I
`I
`I
`I
`I
`9 3 9 4 9 5 9 6 9 7 9 8 9 9
`
`M a r k e t R e s e a r c h
`in D, F, I and S
`
`T e s t s
`
`S y s t e m D e v e l o p m e n t
`
`........
`
`T e s t s
`
`Feasibility Study
`
`Function Development
`
`'L.J I
`
`B R I T E E u R a m I I I
`A p p l i c a t i o n B E - 9 7 - 4 1 3 7
`8,3 M ECU - 20 Partners
`i n c l . 7 R e s e a r c h I n s t i t u t e s
`
`M A Y
`
`2002
`
`3 o f
`J u n e
`
`••
`r I
`
`I n i t i a t i v e
`
`A c t i o n P l a n
`
`1 9 9 2
`
`During phase III of the project, the experiences and investigations were transformed into
`draft regulations that were approved by GTB at their 92nd session at Kyoto in 2001 and
`transmitted to GRE as working document in January 2002.
` During the AFS phase II a special overhead sign lighting had also been developed and
`tested. During discussions in GTB it was omitted from the set of requirements since modern
`retroreflective traffic signs are adequately visible with spread light intensities of about 100 cd.
`Therefore no special lights were felt necessary.
`This report summarises the research aspects that let to the requirements as specified in the
`draft documents for
`1) a new AFS Regulation (TRANS/WP.29/GRE/2002/18 and 19) and
`2) amendments for mounting and operating requirements of AFS systems
` in ECE Regulation No. 48 (TRANS/WP.29/GRE/2002/20).
`
`HW - April 30, 2002 - AFS/GRE/Back-up.PDF page 5
`
`

`

`GRE 48 - Informal 30
`
`2. Glare and Visibility under night time traffic conditions
`
`2.1 Glare from headlamps on traffic roads
`Discomfort glare is the judgement of a person whether glare is unbearable, disturbing or
`absent. The glare sensation is directly related to stress by over-excitation of the receiver cells
`in the eye. Different from discomfort glare, disability glare can not be judged. It needs to be
`measured and tells to what extent the eye adaptation and therewith the threshold sensitivity is
`at a given adaptation luminance and how this threshold is increased by glare. However, this
`threshold difference of luminance that makes an object distinguishable from its surround
`gives alone no understanding of what can be seen and what not. For this purpose the
`luminances of the target and its surrounding must be known. These luminances depend from
`reflection properties of e.g. the road and a pedestrian, and from the illuminance from the
`headlamp on the pedestrian and on its background. For both, discomfort glare and disability
`glare, formulas have been established from experiments. They show that the detectable
`luminance threshold and the discomfort glare rating depend from the adaptation luminance
`(Lad/cd/m2), from the eye illuminance (Eeye / lx) and from the glare angle (Q / degrees) for which
`the exponent depends on age.
`
`DISABILITY GLARE
`
`Schmidt-Clausen/Bindels 1971
`
`young: 1,8
`
`aged: 2,2
`
`DISCOMFORT GLARE
`
`Schmidt-Clausen/Bindels 1971
`
`D D L =
`
`2,0QQ
`L = 0,013 + 0,037 x L + 0,419 ( E / )
`a d
`e y e
`m i n
`
`L
`
`against a dark background
`
`2
`E = I/r cos QQ
`
`e y e
`
`0,46
`QQe y e
`W = 1,59 + 2 log (1 + L ) - 2 log (E / )
`a d
`
` H.J. Schmidt-Clausen, Bindels; Disability glare, J. Lichttechnik 10+12, 1971
` H.J. Schmidt-Clausen, Bindels; Assesment of discomfort glare, J. Light.Res.Techn. 6, 1974
`Different from day time condition, where the visible luminance difference ranges at less than
`1/100 of the adaptation luminance, an object must differ at least as much as 1/10 of the
`adaptation luminance in order to be visible under road and vehicle lighting conditions .
`
`1 0 0 0 01 0 0 0 0
`cd/mcd/m 2 2
`
`1 0 0 01 0 0 0
`
`r i g
`c
`
`r i g
`g b
`r li n
`e
`
`r i n
`r
`o
`
`d
`
`g l a
`b
`
`
`1 0 01 0 0
`
`targettarget
`
`luminanceluminance
`1 01 0
`
`h t
`o m f o
`
`h t i n b
`e o f d i s
`LL a da d
`
`r t
`
`d e t e c t a b l ed e t e c t a b l e
`
`
`l u m i n a n c el u m i n a n c e
`
`d i f f e r e n c e :d i f f e r e n c :
`
`d u r i n g d a y t i m ed u r i n g d a y t i m e
`
`
`< 1 / 1 0 0 o f L < 1 / 1 0 0 o f L a d a d
`
`s
`
`s
`
`e
`
`n
`
`w i t h v e h i c l e l i g h t i n gw i t h v e h i c l e l i g h t i n g
`
`
`
`
`> 1 / 1 0 o f L> 1 / 1 0 o f La d a d
`
`11
`
`0 , 10 , 1
`
`o r d
`
`b
`
`k
`
`c
`
`e o f b l a
`b la c k in b la c k
`
`e rli n
`
`0 , 0 10 , 0 1
`
`
`0 , 1 1 1 0 1 0 0 1 0 0 00 , 1 1 1 0 1 0 0 1 0 0 0
`
`
`background luminancebackground luminance
`H.W. Bodmann und Voit, Versuche zur Hellempfindung, J. Lichttechnik Nr.8, 1962
`
`cd/mcd/m 2 2
`
`[ B o d m a n n 1 9 6 2 ]
`
`Any glare source in the visual field, whether present during a short or long period of time,
`rises the adaptation luminance and therewith the discernible luminance threshold. This glare
`influence is due to light scatter in the eye, that - for older persons with starting cataract - is
`more than it is for young persons. Older persons have also less acuity and need more light
`for the same visual performance. Today, great concern exists with increasing glare. This has
`different reasons from which one is age and the greater glare sensitivity of older persons.
`The statistically increasing average age of the population shows that the majority of drivers
`of motorised vehicles (in 2020 near to 70%) is aged over 50. Persons of that age are more
`
`HW - April 30, 2002 - AFS/GRE/Back-up.PDF page 6
`
`

`

`GRE 48 - Informal 30.
`
`glare sensitive and also have less visual acuity. The increasing number of complaints on
`glare and requests to the parliament to take action against glare, underline this. Thus glare
`and visibility under vehicle front lighting conditions form a key issue that needs a profound
`understanding in order to develop effective lighting improvements.
`GERMANY'S LIFE TREE - EUROPE DEVELOPS SIMILARLY -
`
`1 0 0
`
`9 0
`
`8 0
`
`7 0
`
`6 0
`
`5 0
`
`4 0
`
`3 0
`
`2 0
`
`1 0
`5
`
`1 9 1 0
`
`1 9 8 7
`
`1 9 9 6
`
`2 0 2 0
`
`2 0
`
`5 0
`
`> 50 YEARS
`
`18 TO 50
` Y E A R S
`
`3 0
`
`<18 Y.
`
`3 8
`
`4 2
`
`2 0
`
`4 3
`
`4 4
`
`1 3
`
`64
`
`2 8
`
` 8
`
`
` 2 1 1 2 3 3 2 1 1 2 3 2 1 1 2 3 2 1 1 2 3 2 1 1 2 3 3 2 1 1 2 3 2 1 1 2 3 2 1 1 2 3
`M i o
`M i o
`M i o
`M i o
`
`a g e
`g r o u p s
`
`1 0 0 %
`
`9 5 %
`
`9 0 %
`
`8 0 %
`
`
`The AFS project was particularly set-up to address the needs of older drivers for improved
`vehicle front lighting that would compensate for their loss of acuity and take care of increased
`glare sensitivity due to eye cataract. In the following, therefore, the relationship of visibility
`and glare are addressed in more detail.
`
`Influence of lateral distance of glare sources on glare
`2.2
`Country roads are dual carriageways where opposing traffic flows at rather short lateral
`distance that makes glare from headlamps and reflexes on wet roads a special item of
`concern. On motorways the lateral distance is much greater and reflex glare is shielded by
`the crash barriers. This reduces the glare effects for opposers considerably.
`
` RC 7
`< 6 0 k m / h
`
`E C E - S t d .
`
`. .
`
`
`
`1 , 51 , 5
`
`. .
`
`0 , 2 5
`
`5 , 5
`
`6 m
`
`1 , 5
`
`0 , 2 5
`
`0 , 5
`
` RC 11,5
`< 1 0 0 k m / h
`
`( A - R o a d )
`
`3 , 5
`
`. .
`
`2 , 5
`
`. .
`
`7 , 5
`
`8 , 5 m
`
`1 , 5
`
`0 , 5
`J
`
`4a±sl p J ~ • • ~ J
`i _ r= _ .. " __ ..l-
`.....--------.A=,::_ _ _ r=i.___r~=~~~---,_.
`ij ;:ma~ f -4~1
`. .
`
`S i d e
`D i s t a n c e s
`
` 1 , 5 2 , 5
`R u r a l a n d U r b a n
`
` 7 , 7 0 1 1 , 4 5 1 5 , 2 513,70 17,45 21,25
`
`I n t e r s t a t e H i g h w a y
`E u r o p e a n M o t o r w a y
`
`M 27 (33)
`No speed limitation,
`or 120 to 130 km/h
`
`E u r o p e a n S t d . 4 L a n e M o t o r w a y C r o s s S e c t i o n
`( U S A I n t e r s t a t e H i g h w a y i n b r a c k e t s )
`1 5 , 2 5 ( 2 1 , 2 5 )
`
`.
`
`.
`
`.
`
`.
`
`.
`
`.
`
`.
`
`.
`
`1 1 , 4 5 ( 1 7 , 4 5 )
`
`7 , 7 0 ( 1 3 , 7 0 )
`
`~
`
`•
`
`0,75
`
`7 , 5 0
`
`ii -
`
`EU 4 meter
`U S A 1 0 m e t e r
`
`0 , 7 5
`
`0,75
`
`2 7 m ( 3 3 m )
`
`7 , 5 0
`
`2 , 5 0
`
`1 , 5 0
`
`0,75
`
`
`Since the lateral viewing angle under which the headlamps of opposing vehicles are seen
`has great influence on glare, the glare on motorways is much less than on dual carriage
`ways. For roads of 6 meter width (RC7) the ECE glare limitation in EB50 and for zone III was
`introduced in the 60th. The need of limiting glare on the rather small traffic roads had also
`been reason to develop shielded filament lamps "R2" in 1924 and similar halogen lamps "H4"
`in 1971. In the USA, at those times, most of the traffic flow concentrated already on highways
`
`HW - April 30, 2002 - AFS/GRE/Back-up.PDF page 7
`
`

`

`GRE 48 - Informal 30
`
`with separated lanes. Glare was not seen as important and more attention was given to a
`high utilisation of the luminous flux and a strong hot spot of far reach. This led at the time to
`sealed beam headlamps with differing photometry as compared to Europe.
`Both beam patterns are good for their intended purpose. For an equivalent level of disability
`and discomfort glare, the greater lateral distance and viewing angle on motorways towards
`opposers allows considerably higher glare intensities. The factor of increase relative to the
`European standard road of 6 m width, is shown in the diagram below.
`
`\
`
`\
`'\
`
`' '
`
`D I S A B I L I T Y
`
`G L A R E
`
`F a c t o r > 1 1 0
`
`F a c t o r > 3 0
`
`'\
`
`'
`-
`
`~
`
`"
`"
`
`l
`
`"
`'
`
`'II.
`
`I
`
`I
`
`l
`I
`
`I
`
`.,
`'
`,
`'
`
`I
`
`I
`
`2 5
`
`s / m
`
`•
`
`2 0
`
`D I S C O M F O R T
`
`G L A R E
`
`F a c t o r 2 , 7 5
`
`F a c t o r 2 , 1
`
`1 5
`
`1 0
`
`-
`-
`-
`-
`
`5
`
`--
`-
`On motorways the luminous intensity may increase by a factor of 30 for disability glare and a
`factor of two for discomfort glare. This explains the difference of passing beam photometry
`between the practice in Europe and in the USA.
`
`F a c t o r = 1
`E C E S t d .
`
`..... _
`....
`.....
`
`1 0 0 0
`
`USA Highway
`s > 1 3 , 7 m
`"
`II
`I
`I
`"
`EU Motorway
`s > 7,7 m
`II
`....
`·-
`II
`"
`s = 1 , 5 m
`........
`
`·-
`
`E C E S t d .
`
`1 0 0
`
`1
`
`0
`
`1 2 3 4
`
`F a c t o r = 1
`E C E S t d .
`
`
`
`1
`~
`I
`
`n
`
`I
`
`0
`
`
`
`USA
`Sealed Beam - Highway - Straight - High Efficiency - Higher Glare Values - Pronounced Spot
`
`50 m
`
`35 m
`no strict levelling needed
`
`opposer
`
`70 m
`
`25 m
`
`aa
`Difference in vehicle lighting practice EU / USA since 1920
`
`E U R O P E
`R2 / H4 Design - Country Road - Bended - Low efficiency -Low Glare Values - Wide+Short Spot
`
`50 m
`strict levelling needed
`
`60 m
`
`40 m
`
`o
`
`p
`
`p
`
`o
`
`aa
`
`s
`
`e r
`
`The discomfort glare expressed numerically as glare appraisal mark (W) is shown in the
`diagram below for different glare intensities (cd) for two types of road (RC7 and M27), each in
`dry and wet condition.
`
`HW - April 30, 2002 - AFS/GRE/Back-up.PDF page 8
`
`

`

`GRE 48 - Informal 30
`
`G l a r e a p p r a i s a l a t 5 0 m d i s t a n c e
`B o r d e r l i n e b e t w e e n c o m f o r t a n d d i s c o m f o r t
`
`M O T O R W A Y
`M27
`
`D U A L
`C A R R I A G E W A Y
`RC7
`
`d r y
`
`d i s t u r b i n g
`
`d r y
`
`w e t
`
`u n b e a r a b l e
`
`w e t
`
` W
`
`5
`
`4
`
`3
`
`2
`
`1
`
`6 2 5 1 2 5 0 2 5 0 0 5 0 0 0 1 0 0 0 0 2 0 0 0 0 c d
`G L A R E I N T E N S I T Y
`
`
`The scale of discomfort glare appraisals according to the glare formula on page 6 comprises 9
`steps. A glare mark of 5 defines the borderline between comfort and discomfort (BCD). Public
`lighting installations are designed to have glare marks of more than 4; under vehicle lighting
`glare marks down to 3 are technically feasible and accepted practice. Whether the road is dry
`or wet has no great influence on discomfort glare. On wet roads the lower adaptation
`luminance (dry: ~0,3 cd/m2; wet: ~0,05 cd/m2)causes a slightly higher glare sensitivity. This
`consideration, however, does not yield reflex glare on wet roads; this influence is addressed
`separately under chapter 2.5 below.
`The diagram shows clearly, that for typical dual carriageways of about 7 meter width, the
`glare intensity in zone III should not exceed 625cd (CoP-value). On motorways and for an
`equal glare sensation, however, the luminous intensity may rise to 1250 cd or double the
`value. Higher glare intensities will expectedly create complaints on dual carriageways but also
`on wet motorways and should be avoided. The diagram shows clearly that greater luminous
`intensities of 10 000 to 20 000 cd (or 16 to 32 lx@25m) towards opposing drivers lead to
`unbearable glare - this occures whith driving beam on when the passing beams are wrongly
`levelled such that they emit the high intensities from below cut-off above the horizon - reason
`why special attention needs to be given to proper levelling (see chapter 2.6 below).
`
`2.3 Disability glare and visibility of pedestrians on straight traffic roads
`Disability glare is the reason for rising the eye adaptation (the glare light is scattered in the
`eye and produces a veiling luminance). This increases the threshold luminance that can be
`disccerned. However, the meaning of a visible threshold luminance of e.g. 0,04 cd/m2 in terms
`of visibility fully depends on the illumination of the object and its reflection properties.
`
`c d / m 2
`
`T H R E S H O L D S E N S I T I V I T Y
`
`1 , 0 0
`
`0 , 5 0
`
`0 , 2 0
`
`0 , 1 0
`
`0 , 0 5
`
`0 , 0 2
`
`0 , 0 1
`
`D U A L C A R R I A G E WA Y
`
`d r y
`
`w e t
`
`d r y
`
`w e t
`M O T O R W A Y
`
`
`
`6 2 5 1 2 5 0 2 5 0 0 5 0 0 0 1 0 0 0 0 2 0 0 0 0 c d
`G L A R E I N T E N S I T Y
`
`HW - April 30, 2002 - AFS/GRE/Back-up.PDF page 9
`
`

`

`GRE 48 - Informal 30
`
`Different from discomfort glare, disability glare can not be judged. A driver experiences
`whether he could see a pedestrian or not, after he escaped a near accident or too late.
`Due to the flat incidence of light on the road, the road luminance is rather low. On a vertical
`object such as pedestrians the illuminance is relatively high what makes the pedestrian light
`against a dark background, particularly when situated at and outside the road edges. At the
`kerb of a road, in order to see a pedestrian, the illuminance must be such that the detectable
`threshold luminance is exceeded. With the knowledge of the pedestrians' reflection, the
`necessary illuminance can be calculated.
`Already in the 30th Waldram had introduced "Revealing Power". Revealing power means the
`probability in % that an object, e.g. a pedestrian, can be seen at a particular location. This
`probability depends from the luminance of the pedestrian, that can be calculated statistically
`at knowledge of the frequency distribution of the reflection factors of pedestrians' clothes.
`Revealing Power gives a much better understanding, of what can be seen at a given
`combination of glare intensity and glare source location relative to that of the illuminated
`object.
`
`~~
`
`c u m u l a t i v e
`f r e q u e n c y %
`
`100
`
`.,......---
`
`I/
`
`/
`/ /
`
`5 0
`
`0
`
`/
`
`/
`
`V
`
`/
`
`/ v
`
`V
`
`d i f f u s e r e f l e c t i o n o f p e d e s t r i a n s ' c l o t h e s
`
` L = E x r / pr / p
`
`p p
`D D L x
`
`r r
`
`l i m . =
`
`E
`
`w h e n s e e n a g a i n s t
`
`b l a c k b a c k g r o u n d
`
`t h e t h r e s h o l d l u m i n a n c e
`d e t e r m i n e s t h e p e r c e n t a g e
`
`o f p e d e s t r i a n s t h a t
`
`c a n n o t b e s e e n ;
`
`t h e p e r c e n t a g e t h a t c a n
`
`b e s e e n i s t h e r e m a i n d e r
`
`r r
`
`t o 1 0 0 $
`
`r r l i m
`R P = ( 1 0 0 - P ( ) ) %
`
`--
`
`The disability glare is expressed by the luminance difference that can just be distinguished.
`By approximation it also means the minimum luminance of an obstacle that is necessary to
`see it against a dark background - e.g. when positioned on the kerb of the road. Many
`researchers use the threshold increase, that is the ratio of threshold under glare divided by
`the luminance threshold without glare. But, neither the luminance
`threshold nor the increment gives a clear understanding of what can be seen and what not.
`Therefor the revealing power as described above in chapter 3 is used in the following
`diagram in dependency from the object illuminance for a range of glare intensities. The
`figures of revealing power now indicate the chance in % that e.g. a pedestrian can be seen
`
`1 0 0 %
`
`R
`
`P
`
`5 0 %
`
`W E T D U AL C A R R I A G E R O A D R C 7
`
`> 8 l x
`
`> 2 0
`
`l x
`
`0 c d
`
`6 2 5
`
`1 2 5 0
`
`1 0 0 0 0
`
`2 0 0 0 0 c d
`
`
`
`0 %
`
`0 , 5 1 2 4 8 1 6 l x
`t a r g e t
` i
`l
`l u m i n a n c e
`
`HW - April 30, 2002 - AFS/GRE/Back-up.PDF page 10
`
`

`

`GRE 48 - Informal 30.
`
`To get the necessary luminous intensity towards a target, the object illuminance is to be
`multiplied with the square value of the necessary seeing distance of the target. On a dual
`carriageway (country road) two findings are evident:
`1) in order to improve the chance of seeing a pedestrian fairly (>50%) if not safely (>90%),
` the object illuminance should exceed 3,6 respectively 8 lx. Since both headlamps
` contribute to the object illumination, this means that the illuminance on the measuring
` screen of each headlamp should exceed 8 lx@25m (5000 cd) in point E50R/L and 16 lx
` @25m (10 000 cd) in point E75R in order to give a fair chance of seeing a pedestrian
` or a similar obstacle from 50 m distance.
`2) as already stated above in chapter 2.2, the glare intensity should not exceed 1lx@25 m
` (or 625 cd) in zone III for keeping discomfort glare in acceptable limits.
`
`
`
`
`
`
`
` D R Y M O T O R W A Y M 2 7
`
`7 l x
`
`> 1 0 l x
`
`1 0 0 %
`
`R P
`
`0 c d
`
`6 2 5 c d
`
`5 0 %
`
`1 2 5 0 c d
`
`1 0 0 0 0 c d
`
`2 0 0 0 0 c d
`
`0 %
`
`0 , 5 1 2 4 8 1 6 l x
`t a r g e t
`i
`l
`l u m i n a n c e
`
`
`On a motorway, similar conclusions can be drawn:
`1) Since the speed on motorways is higher, obstacles must be seen at greater distance in
` order to react in time. For motorways the headlamp intensity in E75R should exceed
` 36 lx@25m (20 000 cd) and have halve the values in E50L.
`2) The influence of glare on visibility is much less than on dual carriageways and, as was
` concluded already above for discomfort glare, the glare intensity in zone III may rise to
` 2 lx@25m or 1250 cd (CoP)
`Every increase in target illumination improves the chance to see further away, but it also
`increases the risk that with levelling changes due to load, these high intensities are directed
`towards the opposers where they evoke an unbearable glare sensation (see the diagram on
`discomfort glare on page 9 above).
`
`Influence of the light emitting area on discomfort glare
`2.4
`An other issue of research on glare was dedicated to the influence of luminance or apparent
`surface because it was anticipated that smaller apparent surfaces would be more disturbing.
`According to research by Alferdinck at TNO-HFRI, Soesterberg, Netherlands, such an
`influence was found, be it much less than was expected. In the experiments for the evaluation
`of discomfort glare (page 5) the area of the glare source was about 150 cm2. In his research
`for AFS, Alferdinck found that smaller headlamps increased the discomfort, larger headlamp
`areas decreased it. The influence of the apparent surface on the Glare Appraisal Mark when
`applied to the Schmidt-Clausen-Bindels Formula (page 5) is as follows:
`W = 1,59 + W(Lad,Eeye, Q)
` + 0,54 log [(F / cm2) / (Fn / cm2)]
`J.W.Alferdinck, Discomfort glare - effects of intensity and size, TNO-HFRI Soesterberg, 1998
`This means that the difference in glare mark between a small apparent surface (28,3 cm2 or
`6 cm diameter) and a normal headlamp area (Fn = 150 cm2 or 12 cm diameter) is - 0,4 or
`nearly halve a step worse on the 9 point glare scale. In order not to worsen the comfort and
`
`HW - April 30, 2002 - AFS/GRE/Back-up.PDF page 11
`
`

`

`GRE 48 - Informal 30.
`
`to reach an equal glare appraisal with smaller headlamp surfaces, the luminous intensity
`should be decreased by 33%. This has also been found by other researchers (Adrian, Sivak).
`M.Sivak, Effect of headlamp area on discomfort glare, J. Light.Res.Techn. 22(1), 1990
`K.Manz, Einfluss der Scheinwerfergrösse auf psychologische Blendung, SAE 1999
`However, when the minimum surface of the simultaneously illuminated lighting units of the
`headlamp (see under appearance, chapter 4) are specified to be larger or equal 100 cm2 in
`any case, no additional precaution needs to be taken for the glare intensities of lighting units
`with smaller areas in order to compensate for their higher luminance. The influence of the
`glare source area, however, remains very important for reflex glare on wet road surfaces as
`will be shown below.
`
`2.5 Glare from headlamp reflexes on wet roads
`On wet dual carriageways and in towns the opposers are dazzled by all kind of reflexes from
`which the headlamp reflexes from opposers are generally very disturbing. As research from
`the TU Darmstadt had already shown in context with the VEDILIS project and was verified
`during AFS tests with special passing beams for wet roads, the main reflexes towards
`opposers were found to originate from the foreground illumination by the vehicle headlamps
`at between 10 and 20 meter in front of the vehicle. These reflexes "mirror" the average
`luminance of the headlamps (in that direction) by about 50% when the water film is closed.
`Smooth fine asphalt is very critical in forming closed water layers. The more course road
`surfaces and in particular the ZOAB road surfaces as being used in the Netherlands form no
`such closed layers and produce less reflex glare.
`
`h = 0 , 6 2 m
`
`h = 1 , 1 0 m
`
`2 , 3o
`
`2 , 3o
`
`0 1 0 2 0 3 0 4 0 5 0
`
`(specified lines in the photometric requirements)
`
`m
`
`D
`
`...
`
`..
`C
`
`r e f l e c t e d h e a d l a m p a r e a
`
`The reflexes of headlamps on a wet road are spread over a large area comprising about 20
`m2. The luminance of the road amounts to about 50% of the luminance of the headlamp in the
`direction to the vehicle foreground between 10 and 20m and produces a very high luminous
`intensity towards an opposer - most critically at 50 meter interdistance between the vehicles
`respectively between a vehicle and an observer. The luminous intensity towards the eyes of
`the opposing driver is found by the product of apparent road surface times the reflected
`luminance of the headlamp (~50%) in the mirroring direction. The headlamp luminance is
`given by the quotient of luminous intensity in the mirroring direction and the light emitting area
`of the headlamp.
`I eye, reflex/cd = I headlamp line C x ( F road reflex area x sin 1,6o ) / (Fheadlamp x cos 3,2o) = ~ 38 x I hl, line C
`The indirect glare intensity from mirrored road reflexes is with about 38 times the downward
`intensity by far more than the direct glare intensity from the headlamp and would increase the
`discomfort tremendously, was it not that the great source area on the road is compensating
`this effect in part (see the above chapter on influence of glare source area). To show the
`influence by example, the discomfort glare including the influence of gl