Applied Ergonomics 1993, 24(6), 427-431

An improved motorcycle helmet design for

tropical climates
Rajesh Patel and Dinesh Mohan

Centre for Biomedical Engineering, Indian Institute of Technology, Delhi, 10016 New Delhi,
India

Approximately 20% of all fatal traffic crashes in India involve riders of motorized
two-wheelers. H e a d protection of two-wheeler riders is therefore a very important
issue. This paper reports the results of a survey of patterns of motorcycle helmet use
in Delhi, and the design details of a more comfortable helmet. The survey results
were used as guidelines for designing a safer helmet, with a better ventilating system,
to p r o m o t e wider use. In the new design additional protection is provided on the sides
of the helmet, since our earlier studies showed that more head injuries occur on the
side of the head than on the top. A low-cost locking device has also been developed
with which the helmet can be secured to the vehicle when not in use. All these design
features are incorporated into a stylized product fol:m. The new design is being
m a r k e t e d by a Delhi-based manufacturer and has received a very favourable response
in the market.

Keywords: Helmet, motorcycle, safety, comfort

Introduction marketing their helmets in four sizes: small, medium,

large and extra large. Selling prices of the helmets vary
Anecdotal evidence suggests that helmets are un- from US $2 to $10 for open-face helmets and from $10
popular among riders of motorized two-wheelers to $18 for full-face helmets.
(MTWs) in India because of the discomfort they caused
in tropical climatic conditions. The Indian Motor It is not mandatory for the manufacturers to have
Vehicles Act requires all MTW riders to wear helmets, their helmets certified by the BIS, and a large number
but the law is not being enforced in all states of India of helmets are sold without BIS certification. The
because enforcement of traffic regulations is state- standard requires the helmet to be tested for shock
dependent (Mohan, 1989). There is a small but absorption properties, penetration resistance, strength
vociferous anti-helmet lobby in each state. They have of retention system, flexibility of peak, rigidity of the
been effective in delaying the enforcement of this Act. helmet shell, corrosion resistance of metal parts,
As a result, most states have not yet enforced rules for audibility and peripheral vision.
mandatory helmet use, but a few large cities (including This paper reports a study of motocycle helmet
Delhi) are enforcing the law for riders of MTWs. design, particularly for use in tropical climates. It was
In India, open-face (half-mask) helmets are more carried out at the Indian Institute of Technology, Delhi
commonly used than full-face (full-mask) helmets. The and the National Institute of Design, Ahmedabad, and
outer tough shell of the helmet is generally made from was sponsored by Full Power Works, a Delhi-based
fibre-reinforced plastic (FRP) by a simple hand-laying small-scale helmet manufacturer, and by the Delhi
technique because it is most suitable for batch and Police.
small-scale production. The inner shock-absorbing cap
is made of expanded polystyrene (EPS), but the density Methods of study
and thickness of the material vary from helmet to Helmets of different brands were obtained and
helmet (1(L25 mm). Though different head sizes are studied from the perspective of safety, comfort and
specified by the Bureau of Indian Standards (BIS), only convenience in use. Surveys were conducted to obtain a
two sizes of helmet are generally available for economic better understanding of riders' behaviour and their
reasons: mainly because most helmets are manufactured attitudes toward helmets as a safety measure. Technical
by small-scale industries that are unable to maintain tests of helmet characteristics relalcd to safety were
large inventories. Only the large manufacturers are also carried out.

Vol 24 No 6 December 1 9 9 3 0003~870/93/06 0427q)5 (~ 1993 Butterworth-Heinemann LId 427

An improved motorcycle helmet design for tropical climates

Surveys ten different types of open-face helmet. This included a

T w o different surveys were conducted in Delhi new helmet produced in part on the basis of the results
during February 1987 to gauge helmet users' reactions of the survey. Two different tests were p e r f o r m e d on
to helmet use from the perspectives of safety, comfort these helmets.
and functionality. The first survey was conducted at
various roadside locations to provide quantitative data Shock absorption test on front and rear of helmet A
regarding the types of vehicles on the road, the types of mass of 5 kg was dropped through a free fall of 2500 m m
helmet in use, the types of different helmet accessories, (guided by two metal wires) on the helmet positioned
the colours of vehicles and helmets, use of the helmet onto a headform as prescribed in the BIS standard
and strap, and the age and sex of the riders. A total of 4151:1982 (BIS, 1982). The test set-up for the front
200 observations were made, at ten different locations and rear impact tests is shown in Figure 1. The forces
at different times of day. Observations were noted on a were measured by a Kistler dynamic force transducer
specially developed recording sheet for every passing which has a frequency response of 10 kHz. The force
two-wheeler at 1 min intervals. Locations were selected curve was plotted on a Hioki 8803 FFT Hi Corder and
in such a way that there would be no obvious bias in recorded on a Jiwatsu digital storage scope type SS-
traffic: for example, away from residential locations or 5802. All the tests were p e r f o r m e d at room temper-
industrial sites. ature. All helmets were first tested on the front and
then the test was repeated on the back of the same
The second survey was conducted by circulating a
helmet. The permissible limit of 20 kN (as per BIS
questionnaire to obtain information on riders' views
standard) impact force in these tests was considered the
about helmets in relation to safety, comfort and
m a x i m u m permissible limit.
convenience. Questionnaires were given randomly to
M T W riders at different locations in Delhi, until a
sample of 100 returns was obtained. Items covered in
Helmet drop test on side of helmet A steel surface with
the questionnaire are summarized in the Appendix. a covered u p p e r face was fixed on top of the force
transducer (Figure 2) and the helmets on their head
forms were dropped on to this surface (radius 40
Impact tests
m m ) from a height of 1500 m m such that the centre of
Shock absorption tests were p e r f o r m e d on a total of
gravity of the headform was aligned with the centre of
the force transducer. T h e transmitted force was recorded
on a Kistler dynamic force transducer for each test and
plotted on a Hioki 8803 F F T Hi Corder. The tests were
p e r f o r m e d on one side and then the same test was

i i
"[1

ii
~ j
I I

j t" Guide pdlar

I
Helmet
i.
Wooden head form
i ~ Charge Digital
amplifier storage scope Hi corder
/

ri ~,
£i .... I I:

o j ~....J _ . i ...... L_i . . . . . . . . L....

q ii
DynamLc 1 J J
force ] i Curved metal surface
transducer I ! 4 0 m m radius J ]
~" , ,/ I

G. . . . d ~ _ i - ~ ---J i
level [-:- ~ - - ~ - ' 7. . . . ~ L

Metal Metat ;
plate disc ;
! m deep RC block

Figure 1 Test set-up for front shock absorption test Figure 2 Test set-up for helmet drop test

428 Applied Ergonomics

 R PATEL AND D MOHAN

repeated on the other side of the helmet. This test is not Table 1 Results of the behavioural study of helmet users
prescribed in the BIS standard. However, since most
impacts in two-wheeler crashes are sustained on the Riders' views on helmet storage at parking lots
sides of the helmet (Mohan et al, 1984), we consider 1 Riders always carry their helmets with 38%
this to be an important test. them
2 Riders carry their helmet only if there is 46%
Results no proper parking place
Figure 3 shows the proportion of different types of 3 Riders lock their helmet in helmet storage 7%
motorized two-wheelers found on the streets of Delhi compartment of their scooters
from our survey. We have no reason to suppose this 4 Riders secure the helmet strap in strap 5%
does not represent the true picture in Delhi, but the lock
proportions may be different in other cities of India. Of 5 Riders lock the helmet strap under 4%
those wearing helmets, 92% used half-mask helmets toolbox cover
and only 8% used full-mask helmets. Of the helmets, Riders' views on carrying their helmets
73% did not have any kind of eye protection (visor). 1 Very inconvenient, but they are forced to 64%
Out of the total riders, 69% had their helmets strapped carry in absence of a reliable helmet
properly, 5% bad helmets untied, 24% bad straps that locking system
were loose and 2% had helmets with no straps at all. 2 Inconvenient to some extent 29%
Pillion riders accompanied 27% of the M T W riders. A 3 Convenient 7%
majority (55%) of the MTW riders were in the age
group of 26--50 years, because in India MTWs are Riders' reactions on helmet discomJort due
generally used as family and commuting vehicles rather to heat, especially in s u m m e r months
than for leisure purposes. 1 Uncomfortable 72°/,,
2 Comfortable 28°/,,
Riders did not have m a j o r complaints about the size
and weight of helmets. It was found that 84% of the Riders' measures to alleviate the discomJort
riders carry their helmets with them after parking their due to heat
vehicles and 93% of the riders complained about the 1 Riders remove the helmet for some period 8°/,,
resulting inconvenience (Table 1). A majority of the while riding
riders (72%) reported that helmets cause discomfort 2 Riders take small halts to remove the 30°/,,
due to heal in the s u m m e r months. helmet and then start again
3 Riders avoid using the helmet until they 12%
Product analysis and development of a new are forced to use
helmet 4 Other solutions 13o/,,
5 No answer 37%
Helmets of different types and makes were studied
from the technical, ergonomic and aesthetic points of
view. After discussions with a manufacturer, broad
and 600 mm), at present the manufacturer is marketing
guidelines were established for the development of a
the newly designed helmet in one size only (590 mm)
new design of helmet. As the manufacturer owned a
small-scale enterprise, the technical limitations of the owing to financial constraints. His distributors and
small-scale manufacturing process and low product cost retailers are unable to stock the helmets in different
were the prime considerations in the development of sizes; in their limited space they prefer to stock as many
the new design. brands and models of helmets as possible, but of
different colours rather than of different sizes.
Though we r e c o m m e n d e d different helmet sizes, as Figures 4 and 5 show the new design of the open-face
specified by the Bureau of Indian Standards (headband helmet in which ventilation is provided by slits in the
circumferences of 5 2 0 , 5 3 0 , 5 4 0 , 5 5 0 , 5 6 0 , 5 7 0 , 580,590 front, back and sides. These vents can be closed easily
in winter by a snap-on plastic fitting or by a cotton wool
plug from inside. With marginal increase in cost, the
> IOOcc bike 12% vents can be made adjustable for controlled air circula-
tion. The helmet can be locked by looping a strap
through the slot provided on the sides of the helmet and
< IOOcc bike 5 5 %
around any fixture on the vehicle (tzigure 6). In the new
design, additional safety padding is provided on the
Moped 4 . 5 %
sides of the helmet as our earlier studies showed that
more head injuries occurred to the sides of the head
than to the top (Mishra et al, 1984: Mohan et al, 1984).
The side padding also gives protection against the small
flying insects which very often get trapped inside the
Scooter 7 7 °A
ears, by filling the gap between the helmet and ears.
These design features were incorporated into a stylized
product form, which is being manufactured by a Delhi-
Figure 3 Proportion o l ditfcrcnt types of two-wheelers on based small-scale industrial enterprise. It is being
Delhi roads markcted at the price of US $8.5/I and has received a

Vol 24 No 6 D e c e m b e r 1993 429

 An improved motorcycle helmet design for tropical climates

favourable r e s p o n s e in the m a r k e t ; at least three o t h e r

m a n u f a c t u r e r s have copied the designl

Impact tests results

Test results of shock absorption tests p e r f o r m e d on
nine different types o f open-face helmet (1 to 9), and
on the new helmet, are shown in Figures 7 and 8.
H e l m e t s n u m b e r e d 2, 3 and 4 were BIS certified.
Figure 7 shows the c o m p a r a t i v e ranking o f all helmets
in descending o r d e r for their p e r f o r m a n c e in the s h o c k

Helmet I

New d e s a
in ,:. :...::.>>.:,, Max force

Helmet 2 Min force

? E
Helmet 3 ~-.,-~.,,J~.,~.~111a
Figure 4 New design of helmet
Helmet 4 • • ' " -""'" "t

Helmet 5 • .. '.." .".'.1

Air
inlet Helmet 6

Helmet 7 z-x~~J~f/.-1
,, ,,--,--,. .............. "1

Air
.outlet Helmet 8 ~~.~,.-,.-,.~..-,/,~

Helmet 9
i ~ t i --~
0 I0 20 30 40 50
Impoct force (kN)
Figure 7 Front impact forces in shock absorption tests (open-
face helmets)

lMean force
Helmet 3
Max force
New design
Mm force
Figure 5 Technical features of the new design. Key: 1 - FRP Helmet 8 ~-'~'..............i:
shell; 2 - EPS cap; 3 - inner lining; 4 - neck padding; 5
clearance padding; 6 - locking slot; 7 - side padding; 8 - chin Helmet I
cushion
Helmet 4 ~ f J f f f f / / J / / ~

Helmet 2

Helmet 5

Helmet 9

Helmet 6 ......... ' Z L ; . j Z I I .I ". . . . . . - . . . . . .

Helmet 7

0 5 I0 15 20 25
Impact force (kN)

Figure 8 Side impact forces in helmet drop tests (open-face

Figure 6 Helmet-locking device helmets)

430 Applied Ergonomics

 R PATEL AND D MOHAN

absorption test on the front of the helmet. It shows ducts in respect of its biomechanical and ergonomics
clearly that the new design of helmet performed better characteristics.
than most of the helmets, including the BIS certified
helmets. Figure 8 shows the comparative performance Acknowledgements
ranking of the helmets in the shock absorption tests on This project was sponsored by Full Power Works, a
the sides o f the helmets. This shows that the provision of Delhi-based helmet manufacturing firm. We thank Dr
the extra padding on the sides of the new design of Alok R. Ray, Centre for Biomedical Engineering, IIT
helmet has improved the shock-absorption properties Delhi, and Mr S. Sethuraman, National Institute of
of the helmet. This is shown also in Figure 9 where the Design, A h m e d a b a d for their valuable suggestions and
impact force-time curve of the new helmet is compared guidance during this project. Mr P. N. Sood helped in
with three BIS certified helmets (numbers 2, 3 and 4). the fabrication of prototypes and testing of the helmets.
The curves show that the new helmet records lower We should like to thank the Delhi Police for providing
peak forces than two of the leading brands. This is funds and helmets for safety assessment of motorcycle
because the impact forces are dissipated over a longer
helmets being sold in Delhi. Mr Mahesh G a u r and Mr
time period for the new helmet as compared with the
Amit Vadhera helped in m a n a g e m e n t of data on the
other two. Helmet number 3 performed better than the
computer.
new design, but we are unable to provide a definitive
explanation for this difference, because the padding in
References
helmet n u m b e r 3 is not better than that in the new
design. It appears that the performance of helmet BIS 1982 Indian Standard Specification for protective helmets
n u m b e r 3 is the result of the particular combination of for scooters and motorcycle riders (Second revision), IS:
shell and padding. 4151-1982 Bureau of Indian Standards, New Delhi
Mishra, B K, Mohan, D and Banerji, A K 1984 'Two-wheeler
Conclusions injuries in India: a study of crash victims hospitalized in a
neurosurgery ward', Accid Anal Prey 16 (5), 407~16
• Motorcycle helmet users all over the world have Mohan, D 1989 'The Indian road user and the Motor Vehicles
resisted the imposition of compulsory helmet use Act 1988' in Move Safe 89: National Seminar on Motor
laws. It is therefore necessary to understand the Vehicles Act 1988 and Provisions for Road Safety Civil
reasons for their resistance in each specific situation. Engineering Department, University of Roorkee,
Roorkee, pp 98-103
• This study shows that a careful analysis of users' Mohan, D, Kothiyal, K P, Mishra, B K and Banerji, A K 1984
perceptions and behaviour can lead to a better 'Helmet and head injury study of crash involved motor-
understanding of their needs for the design of cyclists in Delhi' in Proc 1984 lnt I R C O B I Conf on
helmets, especially from the ergonomics point of Biomechanics oflmpacts, IRCOB1, Bron, France, pp 65-77
view. Mohan, D and Patei, R 1992 'Safety assessment of motorcycle
helmets being sold in Delhi' Centre for Biomedical
• O u r study shows that direct and close collaboration Engineering, Indian Institute of Technology Delhi, New
of biomechanics and ergonomics researchers with a Delhi
helmet manufacturer resulted in a product develop-
ment process which combined the theoretical with
the feasible. The motorcycle helmet produced through Appendix: Survey 2 questionnaire
such a process is not only competitive in the market The second survey questionnaire contained the follow-
but also performs better than similarly priced pro- ing items:
1 age and sex of the riders;
2 type of their vehicle;
3 type of their helmet and its cost;
25 4 subjective questions on helmet comfort, size and its
¢/---- Helmet 4 weight;
5 type of security measures they adopt for their
2O
II helmets after parking their vehicles: whether they
i. Helmet 2 carry their helmets along with them every time or
o
they secure with their vehicles. If they secure, what
0 type of locking methods they use;
"~ ~0 6 riders' views on carrying their helmets;
7 type of retention system of their helmets;
E
// .."".,
,/---New design
8 riders' reactions to helmet discomfort due to heat,
especially during the summer;
¢- 9 type of remedial measures that riders adopt to
alleviate the heat discomfort;
10 riders' reactions on mandatory helmet wearing law
for M T W riders.
-5 i i * i i

0 ,3 4 5 6 7 All questions had options to choose from and the

Time(ms)
riders were asked to select one or more appropriate
Figure 9 Impact forces on helmets in side impact tests options for each question.

Vol 24 No 6 D e c e m b e r 1993 431