(March 3, 2019 at 11:51 am)PRJA93 Wrote:(March 3, 2019 at 10:25 am)Jörmungandr Wrote: While I agree with your general thrust, Brian, I think, if I'm not mistaken, research has shown that it is variance which is to blame for more accidents and fatalities, not the speeding itself. While you may feel justified in not matching the speed of the traffic around you if that traffic is going faster than the speed limit, your doing so is more likely to result in an accident or even a death. I think in the grand scheme of things, that outweighs your concerns for the legality and possible ticket you might receive. That being said, the appropriate thing is for faster traffic to stay to the left, and slower traffic stay to the right. That way everybody is happy. If you are speeding in the slow lane, or going slow in the fast lane, then you are the problem.
This reminds me of the debate about when to merge into traffic from an entry ramp. The common intuition is to merge as early as possible, but I believe the conventional wisdom is that you should delay merging until you are required to do so. I don't know if this rests upon any research, or instead is just convention, but again, it appears to be a case where intuition seems to suggest that deviating from the norm is the best course, when in fact it may not be.
There's no research that I know of that shows "variance is to blame for more accidents and fatalities, not the speeding itself."
Three of the top four hits for "variance and traffic accidents" on Google:
Quote:"But when the speed limit is 65 on a roadway with design speed of 80, some people will drive at 62 and some will drive at 75 or 80," he continued. "When all cars are traveling at fairly similar speeds, there is less variance and fewer accidents."
The study was based on the number of fatalities and vehicle miles traveled on individual roadways extracted from New York State Department of Transportation reports.
Absolute mortality decreased by 28.3 percent on the New York State Thruway, the primary focus of the study, when the speed limit was raised from 55 miles per hour to 65 miles per hour., the study found. Adjusted for vehicle miles traveled, there was a 42.5 percent decrease in mortality.
Speed Kills, But on Interstates, Speed Variance Is More Deadly
Quote:An observational study conducted by AAA Foundation for Traffic Safety over the course of 4 years. The study chose 36 locations to conduct their study. These locations included rural interstates, urban interstates, and freeways/expressways. The researchers chose sites that are similar to each other, to limit confounding variables, and that had adequate accident data, adequate exposure data, and that were easy to collect new data. Since the study was conducted over the course of four years, it is reasonable to assume that the sample size is large enough. This study observed a direct correlation between speed variance and accident rate.
The consequences of speed variance
Quote:"They drive too fast" is the cry of many citizens when discussing how people drive on Interstate 81. At times this refrain is directed to the trucking industry and at other times to drivers in general.Consequently, some people have suggested the speed limit should be lowered to 55miles per hour on I-81.
However, research shows that faster travel is not necessarily associated with an increased risk of being involved in a crash.
When vehicles travel at the same speed in the same direction – even high speeds, as on interstates – they are not passing one another and cannot collide as long as they maintain the same speed.
Conversely, when vehicles are traveling at different rates of speed, the frequency of crashes increases, especially crashes involving more than one vehicle. The key factor is speed variance. The greater the speed variance, or the distribution of speeds, the greater the number of interactions among vehicles. Thus, passing maneuvers and opportunities for collision increase. Speed variance, not necessarily high speed, is associated with an increase in the frequency of crashes.
Interstate highways in Virginia such as I-81 generally are designed to accommodate traffic traveling 70 mph. This is called the design speed. Typically, people drive at or near the design speed because it is comfortable for them. When speed limits are set substantially below the design speed, research and experience show that most drivers will exceed the posted speed limit. In fact, before the rural interstate speed limit was raised to 65 mph in1988, the majority of vehicles were traveling faster than the posted 55 mph.
Research also shows that when the speed limit is below the design speed, there is an increase in speed variance, which is associated with a higher risk of crashes. Vehicles at either end of this speed distribution – the slowest drivers and the fastest drivers – are more likely to be involved in crashes.
Virginia DOT || Variance in Speed, Not the Speed Limit, Poses Greatest Risk on Interstate Roads