According to Munteanu’s publication on “Humanand Environmental Factors Contributing to Fatal Road Accidents in a RomanianPopulation”, the study conducted a research about the contributions of humanand environmental factors to the road accidents in Romania. The study analysedthe possible climatic factor involed in road accidents, specifically, thepresense of wet roads, winter condition, fog, and darkness.
They found out thatamong the climatic factors , the mostfrequent factor was darkness. The risk increases if the roads do not haveproper lights.PICS – wet roads,winter conditions, fog, darkness While on Lankarani’s “TheImpact of Environmental Factors on Traffic Accidents in Iran”, the study revealedthat environmental factors are major causes of road accidents. The study foundthat dusty weather had the highest death rate compared to other weather conditions.Based on the study byShankar et. al. (1995), rainfall plays a important role in road trafficaccidents.
They claimed that high rates of fatalities resulting from roadtraffic accidents in poor weather can be explained by poor visibility because ofrainy or snowy weather and the slippery of the road surface which causesreduction of vehicle-roadway friction. In addition, Hijar et. al. (2000)supported the findings of this study. Their study showed a definite associationof adverse environmental conditions such as rain, fog, wet pavement and even daylightwith traffic crashes.Based on Olawole’sImpact of Weather on Road Traffic Accidents in Ondo State, Nigeria: 2005–2012″,the study has examined the role of temperature and rainfall as it affects roadtraffic accidents in Ondo State, Nigeria. The study has particularlyhighlighted the dual roles of temperature and rainfall.
The effect of rainfallon accidents seems to be related non-linearly with accident rates. Studies havefound negative or non-significant correlations between rain and accidentsThe climatic andenvironmental condition is a factor that contributes to vehicle crashes on Ondostate roads according to the study of Aiyewalehinmion “Analysis of Road Traffic Crashes/Collision in Ondo State Roads”. Weathercontributes to the wetting of pavement that reduces friction between the asphaltroad surfaces and moving vehicles. A few percentage of severe crashes occurredon Ondo State roads due to effects of weather. The Figure 1shows the percentage distribution of factors responsible for crashes on OndoState from January 2005 to December 2010. It shows that the effects of weatherdoes not significantly contribute to vehicular crashes in Ondo State roads.
Increasein rainfall is often linked to high accident frequencies according to the studyof Fridstrom et al. (1995), Chang and Chen (2005), Caliendo et al. (2007),Hermans et al. (2006).
However, increase in rainfall has also been found to reducethe number of accidents based on the study of Karlaftis andYannis (2010). They found that, contrary toprevious research, increases in rainfall reduce the total number of accidentsand fatalities as well as the pedestrian accidents and fatalities, a findingthat attributed by more cautions behaviour of the driver. The time varying effects of rainfallhave also been investigated. Eisenberg (2004) has shown that the impact ofprecipitation on a given day is reduced when precipitation was observed in theprevious days, which is possibly due to driver adaptation. In addition to this,Brijs et al.
(2008), have confirmed Eisenberg’s finding that the longer the”dry spell”, the higher the number of accidents when rainfall occurs. Enete andIgu (2011) examined interactions between rainfall characteristics and roadcrashes in Enugu, Nigeria. The study established that almost 30% of roadcrashes in Enugu occurred during wet months.
The study also found that theeffect of rainfall on road accident count dependson the length of time since the last rainfall. Large dry spell days recordedmore accident counts, supporting Eisenberg’sfinding. Based on Karlaftis’ publicationon “Weather Effects on Daily Traffic Accidents and Fatalities: A Time SeriesCount Data Approach”, the study foundthat temperature increase lead to increase onaccidents. This study verifies Scott’s discovery that higher temperatures increase accident frequencies.Extreme temperatures; low in winter and high in summer are positivelycorrelated with road accidents. Also, the number of hours of sunlight appearsto increase road accidents concluded by Fridstom et al.
(1995), Hermans et al.(2006). Based on Brijs et al. (2008) and Stipdonk (2008), the deviations frommean daily or monthly temperatures have been found to increase road accidents.
On the other hand, Hermans et al. (2006) and Stipdonk (2008) concluded that increases in sub-zero temperatures days, lowerthe exposure thus reducing the number of road accidents.