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5. Analytical StudiesPrevious literature from LMICs, and results from the Cameroon study consistently showed alower contribution of situational factors in crashes than those reported in studies from HICs[49]. Nevertheless, we observed that some situational factors were frequently observed atcrash sites. We thought it interesting to assess situational factors associated with injury crashsites on Yaoundé-Douala road section by case-control study, a method never used previouslyto assess such contributions (Study III). Similarly, a high crash fatality associated with roadsection undergoing maintenance, made interesting for us to assess such burden and compare itwith that of normal traffic using historical cohort study methods (Study IV). Both of theabove studies showed that crash circumstances could be better explained when driver- andsituation-related factors are considered simultaneously. This suggested us to develop and testa novel method to assess interactions between hazard perception and situational factors athigh-risk crash sites in voluntary Pakistani drivers (Study V).5.1 Study III: Situational factors at traffic crash sites: a case-control studyon Yaoundé-Douala road section, CameroonSituational factors play an important role in determining risk and severity of an RTC [60].Improving road design for instance, can decrease crash risk by increasing road network abilityto compensate for driving errors [62]. Similarly, installation of side impact barriers at curvesor removal of solid objects reduces crash severity. It is estimated from crash data of HICs thatimplementing road interventions can reduce 20% of the preventable RTCs [49].Installation of road interventions in LMICs is often not effectively advocated, due tounderreporting of involved situational factors at crash sites [50]. As discussed earlier, policereports are the most common RTC surveillance mechanism in LMICs, but they tend to focusonly on road user-related crash factors (Figure 5, page 19). In countries like Botswana, India,and Zimbabwe, road factors were reported in only one percent of crashes [7]. Our results fromCameroon showed that road situational factors were identified in less than 5% of interurbanroad crashes. A similar proportion was observed for interurban crashes in Pakistan [89].These proportions were certainly less than the expected involvement of such factors incrashes as shown in the USA and Great Britain [55].Moreover, previous traffic safety research in LMICs focused more on transient factors such ascrash time or adverse weather conditions [90]. It was observed that, when situational factorswere reported as a crash cause, adverse weather or reduced visibility were identified in overhalf of these crashes [89]. In LMICs, police are not trained to report road factors, informationessential to advocate and implement local as well as area-wide road interventions [7, 91]. Wefound only one cross-sectional study from Brazil, showing that road surface conditions weresignificantly associated with injury crashes on interurban roads [21]. Involvement andcontribution of modifiable situational factors other than weather conditions is rarelyinvestigated in LMICs, particularly using case-control methods [90, 92].36