Time of day is associated with federal highway accidents in Brazil.

According to the most recent Global Status Record of Road Traffic, the number of road traffic deaths continues to rise. The risk of a road traffic death is more than 3 times higher in low-income countries than in high-income countries. However, the effect of time of day on road accidents is barely considered in public policies to reduce the chance of an accident. This study aimed to estimate the chance of an accident for every hour of the day in Brazil. From the raw data on accidents, their hourly distribution was derived, with a one-hour resolution. The data on the flow of vehicles on the highways was similarly organized. In the specific case of the flow, the total average flow for all sensors on Brazilian highways from 2015 to 2017 was used. It was clearly observed that the chance of an accident, in general, is on average 3-3.5 times higher between 02:00 and 04:00 h than during 07:00-19:00 h. Two other peaks were also noticed, the first one at around 07:00 h and a second one around 18:00 h, which were linked to an excess of vehicle traffic (rush hours) but were lower when compared to the chance during the night. The chance of a road accident in the middle of the night was higher compared to the rest of the 24 hours, similar to high-income countries.