A study by researchers at the National University of Singapore and Chinese University of Hong Kong shows that the colour a taxi is painted is a major factor in determining its safety on the road.
This paper investigated the phenomenon that yellow taxis have fewer accidents than blue taxis. Statistical analysis of data collected over three years from a taxi company in Singapore suggested that after ruling out other possible factors such as driver error, the higher visibility of the colour yellow makes it easier for other drivers to avoid getting into accidents with yellow taxis, leading to a lower accident rate. On average, yellow taxis were involved in 6.1 fewer accidents per 1,000 taxis per month— 65.6 compared with 71.7 for blue taxis.
Ho Teck Hua, NUS deputy president of Research and Technology, who led the study, said that the findings suggest that colour visibility should play a major role in determining the colours used for public transport vehicles.
"A commercial decision to change all taxis to yellow may save lives and potentially reduce economic losses by millions of dollars. Our results are also noteworthy to smaller taxi companies and to drivers who use their private vehicles as taxis to work for private hire car services,” Professor Ho said.
“We compared accident rates based on the three lighting conditions used in the reports: “street lighting,” “daylight,” and “no light.” As hypothesized, the relative difference in the accident rate was greater in street lighting (4.5 accidents per 1,000 taxis per month, from 27.8 to 23.3) than in daylight (2.0 accidents per 1,000 taxis per month, from 43.7 to 41.7),” the report found.
The paper went on to suggest that these results might lead to private hire and ride share companies painting their cars a brighter hue. Because yellow is an uncommon colour for private cars, it is likely that similar results would also be observed if taxis of other colours were changed to yellow, it concluded.