20
2 Review of Literature: Motorcycle helmet
would affect the structural integrity of the helmet and increase the risk factor in case
of accidents. Very few research studies have been carried out on the ventilation of air
flow inside helmets. There is limited literature available on systematic investigation
relating to the ventilation and comfort of motorcycle helmets [51].
Some factors that contribute to motorcycle accidents are fatigue, lack of concentration, behaviour and the environment. A study in 2003 revealed that around 40%
of riders reported experiencing fatigue on at least half of their journeys [52]. Long
periods seated in a fixed position while riding a motorcycle result in static muscle
fatigue. Depending on the type of motorcycle, there are more ergonomic constraints
in riding [53]. A high level of concentration is required while riding a motorcycle
compared to driving a car [54]. It has been reported that 14% of total traffic fatalities
in Europe are for powered two wheelers (PTW) [55].
Motorcyclists run 20 times more risk of fatal accidents than car drivers per travelled kilometre [56]. In low-income countries, users of bicycles and motorcycles are
the commonest victims of traffic injuries. This is due to the higher number of PTW
than cars on the road.
A study [57] concerning the accidents of PTW revealed that approximately 10%
of all riders were not wearing helmets while riding in traffic. Bianco et al. [58] investigated helmet usage among teenage PTW riders in south-eastern Italy in summer
and found it to be approximately 35%. This investigation found that, due to thermal
discomfort, PTW riders were prepared to risk an accident instead of wearing a helmet.
A similar conclusion on thermal discomfort was drawn by Hickling [15] in regards
to protective headgear. In Europe, 14% of total yearly traffic fatalities involve PTWs
[55]. The risk of a fatal accident involving a PTW per travelled kilometre is 20 times
higher than for a car [56]. The factors associated with higher PTW traffic accidents
can be attributed to the reduced conspicuousness [57, 59] and higher vulnerability
of PTW drivers [57].
Where comfort in helmets is concerned, the thermo-physiological wear comfort
(i.e. the heat and moisture transport from the helmet to maintain the heat balance of
the body, especially the head) is the most important. The sensational or tactile comfort
is of less concern. The heat and moisture transport from the head into the adjacent
air is a complex phenomenon and has long been recognised to be critically important
for human survival [60]. A large amount of work has been done by researchers on
the role of heat and moisture transfer on thermal comfort [61–64]. The moisture
exchange depends on its state, i.e. whether the moisture is present as liquid on the
fibre surface or as vapour stored internally. Although there are four modes of heat
transfer, in all motorcycle helmets, the cooling is achieved mainly via the modes of
forced convection and evaporation. These are affected by the amount of air moving
over the head. The following section will highlight the various modes of heat transfer.
2 Review of Literature: Motorcycle helmet
would affect the structural integrity of the helmet and increase the risk factor in case
of accidents. Very few research studies have been carried out on the ventilation of air
flow inside helmets. There is limited literature available on systematic investigation
relating to the ventilation and comfort of motorcycle helmets [51].
Some factors that contribute to motorcycle accidents are fatigue, lack of concentration, behaviour and the environment. A study in 2003 revealed that around 40%
of riders reported experiencing fatigue on at least half of their journeys [52]. Long
periods seated in a fixed position while riding a motorcycle result in static muscle
fatigue. Depending on the type of motorcycle, there are more ergonomic constraints
in riding [53]. A high level of concentration is required while riding a motorcycle
compared to driving a car [54]. It has been reported that 14% of total traffic fatalities
in Europe are for powered two wheelers (PTW) [55].
Motorcyclists run 20 times more risk of fatal accidents than car drivers per travelled kilometre [56]. In low-income countries, users of bicycles and motorcycles are
the commonest victims of traffic injuries. This is due to the higher number of PTW
than cars on the road.
A study [57] concerning the accidents of PTW revealed that approximately 10%
of all riders were not wearing helmets while riding in traffic. Bianco et al. [58] investigated helmet usage among teenage PTW riders in south-eastern Italy in summer
and found it to be approximately 35%. This investigation found that, due to thermal
discomfort, PTW riders were prepared to risk an accident instead of wearing a helmet.
A similar conclusion on thermal discomfort was drawn by Hickling [15] in regards
to protective headgear. In Europe, 14% of total yearly traffic fatalities involve PTWs
[55]. The risk of a fatal accident involving a PTW per travelled kilometre is 20 times
higher than for a car [56]. The factors associated with higher PTW traffic accidents
can be attributed to the reduced conspicuousness [57, 59] and higher vulnerability
of PTW drivers [57].
Where comfort in helmets is concerned, the thermo-physiological wear comfort
(i.e. the heat and moisture transport from the helmet to maintain the heat balance of
the body, especially the head) is the most important. The sensational or tactile comfort
is of less concern. The heat and moisture transport from the head into the adjacent
air is a complex phenomenon and has long been recognised to be critically important
for human survival [60]. A large amount of work has been done by researchers on
the role of heat and moisture transfer on thermal comfort [61–64]. The moisture
exchange depends on its state, i.e. whether the moisture is present as liquid on the
fibre surface or as vapour stored internally. Although there are four modes of heat
transfer, in all motorcycle helmets, the cooling is achieved mainly via the modes of
forced convection and evaporation. These are affected by the amount of air moving
over the head. The following section will highlight the various modes of heat transfer.