Certain times on the roads are likely safer than others, but accident numbers do not tell the whole story.
When is the most dangerous time to drive? The safest? Which day of the week is the most dangerous day to be on the road? Which is the safest?
• The most fatal crashes occurred on Saturday, Friday, and Sunday (in that order).
• There were more fatal crashes between 4-7 pm than any other window of time during the week.
Based on its analysis, Avvo concluded that “the safest time to be on the road in 2016 was Tuesday between 1 a.m. and 3:59 a.m., during which time only 311 fatalities were reported for the entire year. In fact, Tuesday was the safest day of the week overall.”
In reviewing the Avvo analysis, other media outlets made similar claims about the data, including that “Saturday is the most dangerous day to drive” and “the most dangerous times to drive are the late afternoon and early evening.”
After reading these summaries, drivers might decide to do most of their driving on Tuesdays, never drive on Saturdays, and avoid late afternoon driving as much as possible. We should be very careful before reaching such conclusions, however.
How can we determine the safest times to drive?
First, we need to focus on accidents, not just fatalities. Avvo analyzed only fatal crashes. It did not examine crashes that involved injuries and/or vehicle damage. When most people think about danger on the roads, they are thinking about their risk of getting in an accident.
Focusing on risk also reveals the major flaw in trying to reach conclusions about dangerous driving times based solely on accident numbers. Whether a particular time on the road is dangerous depends on the accident rate at that time – your actual chance of getting in an accident.
How do we determine the accident rate? We need to divide the accident total for a period of time (the data published by NHTSA) by the total number of cars on the road during that period of time. Without this denominator, the accident totals can be very misleading. Here’s an example:
According to the NHTSA data, the fewest accidents (27,000) occurred between 3-6 AM on Tuesdays. The greatest number of accidents (322,000) occurred on Fridays between 3 and 6 PM. At first glance, Tuesday mornings appear to be much safer than Friday afternoons. But for Tuesday mornings to have been safer in actuality, however, there could not have been more than 12 times as many drivers on the road on Friday afternoons (322,000/27,000). To demonstrate this fact, let’s assume that there were 11 million drivers on the road on Friday afternoons and 1 million drivers on the road Tuesday mornings (11:1 ratio). The accident rates would have been 2.9% on Friday afternoons (322,000/10,000,000) and 2.7% on Tuesday mornings. Tuesday mornings would have actually been safer. Now let’s assume that there were 13 million drivers on the road on Friday afternoons and 1 million drivers on the road on Tuesday mornings (13:1 ratio). The accident rates would have been 2.5% on Friday afternoons and 2.7% on Tuesday mornings. Friday afternoons would have been safer than Tuesday mornings with these traffic volumes. Thus, without reference to traffic volume, the number of accidents can paint a very misleading picture of actual risk.
The Avvo analysis did not calculate fatality rates. The other media outlets reporting on the analysis also failed to do this. Why didn’t they calculate fatality rates? The most likely explanation is because they could not obtain reliable data on traffic volumes at different times of day. The NHTSA, for example, does not include this data with its fatality and accident data. The conclusions reached by Avvo and the other media outlets, therefore, are likely unreliable.
What can we actually learn from the NHTSA accident data?
Does this mean we have nothing to learn from accident data? No. If we make a few defensible assumptions about traffic volume, we can draw some interesting inferences about relatively safer and relatively more dangerous times to drive during the week and on the weekends.
• Weekday and weekend traffic volumes are different
• Weekday traffic volumes are roughly consistent from morning rush hour through the evening rush hour
• Weekend traffic volumes are roughly consistent
With these assumptions in place, we can make some inferences about the safest and most dangerous times to drive during the week and on the weekends.
• The safest days to drive, from safest to least safe: Monday, Wednesday, Tuesday, Thursday, and Friday.
• The morning commute is safer than the afternoon/evening commute.
• The safest times to drive in the morning are likely the very beginning of the commute (near 6 AM) or the tail-end (near 10 – 11 AM).
• The safest time to drive in the evening is at the tail-end of rush hour (after 6 PM).
• Sunday is safer than Saturday.
• The safest time to drive during the day is Sunday morning.
How can drivers use this information to increase their safety on the roads?
You have less risk of getting in an accident if you leave early and stay late. Staying late does not have to mean working late. As we have previously recommended, exercising after work before heading home, for example, can provide substantial physical and mental benefits. By avoiding peak traffic volumes, you can increase your gas mileage, reduce your time in the car, and improve the quality of the air you breathe.
If you need to run errands during the week, run them during the late morning on Mondays, Wednesdays, and Tuesdays. If you need to run them on a weekend, run them Sunday morning. Enjoy the safety benefits of being on the road with your fellow “Sunday drivers.”
Parents of Teen Drivers:
If your teen is driving to and from school, he or she is driving during the most dangerous times of the day. It is, therefore, especially important to give them tips and tools to stay focused and safe during these drives. For example, ensure that your teen driver leaves on time each day and does not need to rush to get to school, which can lead to many unsafe driving behaviors. In addition, make sure your teen puts his or her phone away (e.g., in the glovebox) or on “do not disturb” while driving. Distracted driving is a leading cause of teenage driving accidents.
Even though accident numbers, standing alone, do not paint an accurate picture of risk on the roads, we can draw some defensible inferences about the safest and most dangerous times to be on the roads. Drivers can use this information to make their daily drives a bit safer, and we hope that they will do so when commuting, running errands, or driving to and from school. Please Drive2Save.