ABSTRACT

HELMET AND HEAD INJURY STUDY OF CRASH

INVOLVED MOTORCYCLIST S IN DELHI

Dinesh Mohan and K . P . Kothiyal C entre for Biomedical Engineering

Indian Institute of Technology New Delhi - 1 1 0 0 1 6

and

B .K . Misra and A . K . Banerj i Department of Neurosurgery

All India Institute of Medical SciE:nces N ew Delhi- 1 1 0 02 9

This paper presents the results of studies conducted in Delhi , India , on the pattem of motorized-two-wheeler and helmet u se pattems , injuries to two­wheeler crash victims hospitalised in a neurosurgery ward , police reported fatal c rashes and biomechanical evaluation of crash involved motorcycle helmets . The results indicate that in the absenc e of a law education alone does not convince riders to u se helmets in Delhi and that lack of dri ver training does not seem to be a factor contributing to serious injury and fatal cra shes . Conspicuity and better helmet design are the two most important safety measures for motorcycle and scooter riders .

INT RO DU CTION

The production of motorized-two-wheelers (MTWs ) in India has increased more than five-fold in the last decade whereas that for automobiles ha s not even doubled . In the city of Delhi there are almost three tim e s as many MTWs registered as automobile s and there i s a !arge variation in the masses and velociti es of the various vehicles plying on the road . These vehicles include trucks , buse s , three-wheeler motorcycle taxi s , minibuses and trucks , hand carts , animal drawn vehicles , bicycle rickshas and bicycles . These factors result in MTWs compri sing 1 6 % ( 1 0 7 ) of all traffic fatalities in Delhi in 1 9 8 0 . Pedestrians accounted for 3 3 % , bicyclists 2 1 % , and all motorised 3 and 4 wheelers 1 0 % (not including bus commuters ) . This shows that among motor vehicle occupant s MTW riders con stitute a vast maj ority of crash fatalities in Delhi . This situation is likely to worsen becau se in India the rate of increas e of production of MfWs is much higher than that of automobiles .

The Centre for Biomedical Engineering has been involved in studying the MTW crash problem in all its aspects . Studies have been conducted on the

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pattern of MTW and helmet use in Delhi (1 ) , injuries to two-wheeler crash victims hospitalised in a neurosurgery ward (2 ) , fatal cra shes in Delhi (3 ) , and biomechanical evaluation of motorcycle helmets in use in India . This paper presents the main results of our investigations over the past four years .

METHODS

The detail s of the methodology used to determine patterns of MTW and helmet use , epidemiol ogy of hospitalized MTW crash victim s and fatal crash victim s have been given elsewhere ( 1-3 ) . U se pattern data were obtained by observing 1 2 , 73 0 riders on the roads of Delhi , injury detai ls from a study c onducted on 7 2 MT W cra sh victims admitted over a one year period to the neurosurgery ward of the All India Institute of Medical Sciences , and fatal crash information from data recorded by the Delhi Police for 1 0 7 fatalities over one year . An additional fifty fatal crash reports were analyzed in detail to study the cra sh patterns .

Crash involved helmets were obtained from victims by giving them brand new helmet s (donated for the purpose by a local manufacturer) in exchange . The damage to the helmet was documented and its rol e in th e crash a s s e s s ed by determining a s best a s we could whether the straps were tied before the crash , the location of the helmet after the cra sh and the head injuries sustained by the rider .

To evaluate the mechanical characteristics of crash involved helmets the following measurements and tests were performed :

1 . Type of shell material and its thickness

2 . Thicknes s of the liner (if present) on the l eft , right , front , back and top of the helmet •

3 . A circular plug (3 0 mm diameter) of the liner was cut out with a coring tool from an undeformed area . The dimensions and m a s s of the plug were recorded and then the plug te sted in compre s s ion on an Instron Universal Testing Machine .

In order to determine the properties of such helmets in an undamaged state , brand new helmets of different brands were purchased and the following tests performed :

1 . Force deflection characteri stic s (quasi - static) by testing the helmet in compres sion u sing a wooden headform in inferior- superior , l eft- right and anterior-posterior directions .

2 . 3 0 mm d iameter plugs were obtained from unde formed liners and their densities , dimensions and force-deflection characteri stic s in

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compres sion recorded .

The properties of us ed helmets were as sumed to be s imilar to those new helmets where the shell thickness and liner plug dimens ions and force­deflection properties were similar .

U se Patterns :

In the Union Territory of Delhi only drivers of MTWs are required to wear a helmet by law but all Sikhs and pa s sengers are exempted . We e stimate that a s a result only 6 1 % of the MTW riders are covered by the Jaw and 48 % e nd up u sing helmets which are properly strapped . Chin-cups are still widely u sed ( 5 9 % of strapped helmets ) and so it may be a s sumed that only 2 0 % of all riders are adequately protected . Therefore it is not easy to detect influence of the helmet law by examining fatality statistics alone .

Our survey indicated that 9 3 % of those wearing helmets used the jet type and l e s s than 1 % full-face type . Thi s is largely becau s e full-face helmets a re 2 to 5 times more expens ive than j et-type and they are also very uncomfortaple in tr�pical clim:i.te s . C ompliance of the law varied from 8 0 % on main roads in day time to 4 0 % in residential areas at night . Virtually none of the passeng�rs were observed to be wearing helmets in s pite of the publicity given to the protective value of helmets . This s hows the inadequacy of education in the absence of a law mandating helmet u s e .

C rash Patterns :

MTW traffic volume drops considerably s oon after the evening rush hour and i s almost negligible by m idnight . But cra she s between sunset and sunris e constituted at least 4 0 % o f both the fatal c rash and hospitali zed samples .

Impact site , crash type and crash location for the hospitalized samples and fatal crashes is shown in Table 1 .

These data s how that crash patterns are similar for the hospitalized and fatal crash samples except for single vehicle crashes . A maj ority of the fatal crashes involve heavy vehicles like bus e s and trucks whereas in the hospitalized sample almo st half the cra she s did not involve any other vehicle . This i s probably du e to the fact that MTWs are u sed mainly by working male s for commuting and family needs and not for sporting purposes . Therefore vehicle velocities are relatively l ow and singl e vehicle cra shes are less l ikely to result in a fatality . Wherea s , fatal injuries are more likely to be produced when MTW riders are hit by large vehicles like trucks and buse s .

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TABLE 1

C rash Details Hospitalized Fatal crashes Sample only

1 . Hit from rear 4 0 % 5 7 % s ide 1 6 % 1 4 % front 44 % 2 9 %

2 • Hit by automobiles 1 2 % 1 3 % trucks arrl buses 1 5 % 6 9 %

other 2 5 % 1 3 % Single vehicle 48 % 4 %

3 . On straight roads 8 6 % 7 1 % At intersection s 1 4 % 2 9 %

C RASH DETAILS OF Mrw RIDERS HOSPITALIZED I N A NEUROSU RGERY WARD AND FATAL C RASHES R EC O RDED BY THE POLICE . PERC ENTAGES ARE BASED ON SAMPLES WHERE DETAILS WERE AVAILABLE .

Human Factors :

5 4 % of MTW riders in the fatal sarnple and 4 7 % in the hospitalized group were over 3 0 years old . Among the hos pitalized group 29 % adrnitted having c onsurned alcohol before the crash and only 3 % had l e s s than two years experienc e . These data were not available for the fatal crash sarnple .

· No breath/blood alcohol test were conducted . This indicates that alcohol involvernent in cra she s , especially at night is quite high considering the fact that detail s of other vehicle drivers were not availabl e .

Injuries :

Injury detail s (rel iable) were not available for the fatal cra sh sarnple . Head injury severity of hospitalized riders is shown in Table 2 and loc ation of s kull fractures in Table 3 .

Figures 1 and 2 show the locations of superficial injuries sustained by unhelrneted and helrneted (clairned ) riders respectively . The s e data show that the crown of the head sustained no superficial injuries in both the unhelrneted and the helrneted cases , however this is the area where the helrnet i s designed to give the rnaxirnurn protection . None of the riders sustained a puncture wound by a sharp obj ect but helrnet standards in rnost c ountries including India incorporate a penetration test providing protection against punctures by sharp pointed obj ects . Eleven (3 0 %) of the riders clairning helrnet use su stained superficial injuries in areas which are expected

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A N TE R IOR VIEW

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Figure 1 . LOCATIONS O F SUPERFICIAL INJURIES T O U N H ELMETED MOTORIZED TWO-WHEELER RIDERS HOSPITALISED I N A NEUROSURGERY WARD

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A N T E R IOR VIEW POST E R IOO VIEW

R IGHT LATERA L V I E W L E F T L AT ERAL V I E W

SUPER IOR V IE W Figure 2 . LOCATIONS OF SU PERFICIAL INJURIES TO HELMETED (CLAIMED) TWO-WHEELER RIDERS HOSPITALI SED IN A N EUROSU RGERY WARD

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TABLE 2

AIS SCORE HEL MET U S ED NO HELM ET HELMET U S E TOTAL (CLAIM ED ) UNKNOWN

N D E N D E N D E

l 2 2 4 (6 %) 2 3 4 7 ( 1 0%) 3 6 6 1 2 ( 1 7 %) 4 9 2 2 1 1 1 7 (2 4 %) 5 2 2 3 3 1 1 8 1 2 3 2 (44 %)

2 2 4 3 1 7 1 3 9 2 2 72 ( 1 0 1 %)

N - No N eurological deficit D - Neurological deficit E - Expired

HEAD INJURY SEVERITY OF RIDERS HOSPITALIZED IN A N EU ROSURGERY WARD C LASSIFI ED BY O:JTC OME AND HELMET USE .

Location of Skull fracture

Frontal Parietal Tempora! Occipital Base

TABLE 3

Number helmet u sed

(claimed) 1 1 riders

2 4 s

s

of Fractures * No helmet Helmet use

1 0 riders

s 1 2

7 7 3

unknown 4 riders

1 1

2

*Single fractures of multiple bones are listed under each bone e . g . a fracture extend ing from the temporal bone to the parietal bone will be li sted under both parietal and temporal .

LOCATION OF SKULL FRACTURES OF C RASH VICTIMS HOS PITALIZED IN A N EUROSURGERY WARD .

to be covered by the helmet . This indicates that at the time of impact the helmet wa s no longer on the head or had rotated away .

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The right s ide of face sustained a larger number of injurie s than the left side . We do not know whether thi s is an a rtifact of this sarnple a s no other data on l ocation of facial injuries have been published in India . Some have suggested th at this rnay be due to the fact the vehicles drive on the left of the road in Indi a . It would be interesting to cornpare thi s with data from countries where traffic drives on the cight .

Effect of Helmet U s e :

The police report data were not considered accurate enough for judging effect of helrnet use and only the hos pital based data were used for thi s purpose . Out o f a total of 72 riders only 2 9 (4 0 %) claimed hel rnet u s e "lnd of the se 1 3 adm itted not fastening the helrnet straps . Therefore it is not surprisiny that at least 1 1 riders sustained superficial injuries in area s that should normally have been protected by helmets . However only 24 % of those who claimed helrnet use sustained head injurie s with s everity of AIS 5 whereas the figure for unhelmeted riders was 5 5% and the figures for neuro­logical deficit were 1 4 % and 3 3 % respectively .

Crash involved helmets were obtained in nineteen case::; and for th ese an attempt was m::i.de to judge the effect of helmet u s e on head injury by examining damage to the helmet , known crash detail s and injuri e s su stained . Of the seven c::i.ses with AIS S only 5 wcre judged to have had their helmets on their heads during irnpact . Only 1 of these five suffered skull fracture . In 4 or the 5 cases the impact wa s on the edge of the l iner . There were 4 cases with AIS 4 of which at least one did not appear to have the helmet on the head at the time of impact . In another two cases the irnpact was below the edge of the liner . In a maj ority of the other cases where th e injury was of AIS 3 or lowe r , the impact was at the edge of the liner or lower . This indicates that it is very important that the area covered by the l iner should be much more and extend as low as pos sible to cover the s ides of the head and face . In those cases w here we judged the helrnet not to have been on the head during impact we could not deterrnine whether this was due to a fault in the retention system or that the strap wa s not tied at all .

Becaus e of the small sample it is not po s s ible to do a statistical analysis to evaluate the protective benefits of helrnets . However , the data give clear qualitative evidence that almost any helrnet when used propedy does p rovid e protection to motorcyclists .

Helrnet propertie s :

Nineteen helrnets were obtained frorn cra sh involved MTW riders who were adrnitted to the hospital . The darnage to these helrnets were recorded and a re shown in Figure 3 . In most cases the darnage i s on the sides and not on the crown of the helmet . Here again there are rnore irnpacts on the right s ide than on the left . All the helmet shell s were made of fibregla s s with

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thickn e s s of most varying from 2 . 5mm and 3 . 5mm . All had polystyrene l iners with thickne s s ranging from 1 Omm to 2 5mm . Within each helmet the l iner thic kne s s could vary by 2 - 6mm with the c rown being the thickest .

The dens ity of plugs cored out from undeformed parts of the polystyrene l iners varied from 1 . 9 x i o-5 to 3 . 5 x 1 ()-5 kg/m 3 .

Two brands of new helmets representing the thin and the thick liner and s hell material were tested in compres sion using a wooden headform on an Instron Testing Machine at qua si- static strain rates . The se helmets represent the two ends of the range of helmets obtained in the study . This was a scertained by comparing the density and thicknes s o f liner material s of these hel met s . The force deflection curves for these helmets are s hown in Figure 4 .

The se curves show that the Indian helmet with the stiffer and thicker liner (helmet E in Figure 4) is 1 softer ' than the U . S . made Bell hel met . Helm et E i s two to three time more expen sive than the most comm only u sed helmets of type S . The latter i s much s ofter and the liner "bottom s out " at loads a round 8 X 1 o3 Newtons in SI direction and less than 2 X 1 o3 Newtons in the L-R direction . Indian helmet E can tolerate at least twice the se loads in both directions and the Bell helmet almost three times in the SI direction .

DISCU SSION

The traffic patterns in Delhi are very different from most metropolitan citie s in high-income indu strialised countries mainly becau se of the large variety of vehicle types present on the road and the differences in their masses and velocitie s . Riding speeds are al so affected because maj ority of MTW riders in Delhi are in general older than MTW riders in Europe and the U . S .A . and they do not use their vehicles for sporting purposes . Studies from high­income countries ( 5 , 6 ) report that a very large number of MTW riders have l e s s than 1 year 's experience whereas only 2 out of 72 of the cra sh victim s i n our sample o f hospitalized riders reported driving experience of less than two years . This sugge sts that driver education may not effect MTW fatality and serious injury rates in Delhi . This may also account for the l ower percentage of s ingle vehicle crashes . Therefore in De lhi more attention would have to be given to reducing conflict between MTWs and high m a s s vehicles like buses and trucks .

For some time the curbside lane was reserved for buses on many roads in D elhi but thi s was not successful partly because the very slow vehicles (animal or human powered) also used the se lanes . This practise has now been virtually given up . Some other innovative ways of traffic management have to be developed to seperate traffic . Further restrictions on truck m ovement and heavy vehicle speed s would be advi sable .

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A !arge proportion of riders , both in the fatal and the hospitalized san ple were hit on the straight road and not at intersections , -: speciall y at night . In both samples more than 4 0 % were hit from the rea r . The proportions are much higher than reported in rnost other studies (S , 7-9) . Crash detail's recorded in the police reports and those given by the hospitalized riders suggest that incon spic-.iity of the rider and motorcycle rnay be a seriou s problern a s rnany streets are not well lit . Because of the tropical weather conditions it is not possible for riders to wear bright coloured jackets l ike the one s worn in colder clirnates all the year around . Therefore it is very irnportant for the MTWs and the helrnets to be rnade rnuch rnore conspicuou s .

A study conducted at the Centre for Biorned ical Engineering ( 1 0 ) shows that g iven the lighting conditions in Delhi at night and the bright sun l ight in the daytime there are only two colours - bright yellow and orange - which are c onspicu ou s at all tirnes . Therefore we suggest that al l MTWs and helrnets s hould be painted only in these two colours and their conspicuity further enhanced by use of reflectors and bigger head and tail lamps .

Head injury data and helrnet analysis quite clearly indicate that though the s ides of the head are rnost vulnerable it is the crown of the helmet wh ich has been designed to provide maximurn protection . Even the rnost expensive Indian helrnets have l iners which are far too s oft especially in the L-R direction . However , our results indicate that even the cheapest helrnets available in India do provide some protection . The degree of protection c an be irnproved by helrnet l iners extending rnuch further down on the side s of the head and with stiffer cornpres s ion properties . The se properties can be optirni sed given the maxirnurn thickness allowable and for velocities at which rnaxirnurn protection i s needed . Serious thought should be given to the advi sability of retaining the pres ent helmet penetration standard . Helrnets a l s o have to be developed with rnuch better side protection without the discomfort perceived by wearers in tropical clirnate s .

This study also showed that some riders sustained serious head injuries in fal l s in single vehicle cra shes at estimated velocities as low as 1 5 krnph . Some of these riders included Sikhs who are exernpted from wearing helrnets as their religion requires thern to wear turbans . Sorne Sikhs believe that turbans p rovide some protection but our study showed no evidence of thi s .

MTW use is growing rapidly in lower incom e countries and safety counter rneasures specifically suited to local conditions have to be evolved . Our experience in Delhi suggests that cons picuity and better helmet de sign are the rnost important i s sues facing us . Howeve r , it would certainly be rnuch rn ore efficient if MTWs are phased out by providing rnore efficient and cornfortable public transportation .

ACKNOWLEDGEMENT

Mr . Sunil Kurna r provided assistance in research and analysis .

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REFERENC ES :

1 . Dinesh Mohan : A Study of Helm et and Motorized Two-Wheeler U s e Patterns in Delhi . AAAM Quarterly/Journal . 5 :4 , 2 9 - 3 2 , 1 98 3 .

2 . B . K . M i s ra , D inesh Mohan and A .K . Banerj i : Two-Wheeler Injuries in Delhi , India : A Study of Crash Victims Hospitalized in a Neuro-Surgery Ward . Accident Analys i s and Prevention , in press .

3 . Dinesh Mohan and P . S . Bawa : An Analysis of Road Traffic Fatalities in Delhi , India . Accident Analysis and Prevention , in pre s s .

4 . H . B . Kingsbury , W . C . Herrick and Dinesh Mohan : High and Low Deformation Characteri stics of ·Motorcycle Helmets . SAE Paper 79 03 24 , 1- 1 2 , Society of Automotive Engineers , Inc . , Warrendale , Pa . , 1 9 79 .

5 . H . H . Hurt : Status Report of Accident Investigation Data : Motorcycle Accident C ause Factors and Identification of C ounter­measures . DOT-HS- 0 1 1 6 0 , NTIS , Springfield , Virginia , 1 9 79 .

6 . J . F . Krau s , R . S . Rigg in s , and C . E . Franti : Some Epidemiological Features of Motorcycle Coll i s ion Injuries-I . Introduction : Methods and Factors Associated With Incidence . American Journal of Epidemiol ogy 1 02 : 1 , 74-98 , 1 9 75 .

7 . S . Kawano : Actual Status and Preventive Measures for Motorcycle Accidents in Japan . Proceedings International Motorcycle C onference, III : 1 2 2 3- 1 2 5 6 , Motorcycle Safety Foundation , Linthicum , Md . , 1 98 0 .

8 . J .A . Newman : Characteri stics of Motorcycle Accidents . Proceedings of the Meeting on Biomechanics of Injurv to Pedestrians, Cyclists and Motorcyclist s , 2 5 0- 2 59 , IRCOBI , Bron , France , 1 9 7 6 .

9 . D . Otte , P . Kelbe and E . G . Suren : Typical Injuries to the Soft Body Parts and Fractures of the Motorized Two-Wheelers . Proceedings of the IRCOBI Conference on Biomechanics of Impacts . 1 48 - 1 6 5 , IRCOBI , Bron , France , 1 98 1 .

1 0 . Dinesh M-0han and S . Mitra : Conspicuity of Different Colours in Varying Light Conditions With Special Application to Conspicuity of Two-Wheelers in Traffic . C entre for Biomedical Engineering , Indian Institute of Technology , New Delhi , 1 9 8 2 .

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