Originally Posted by VinceU
Here's why 40 isn't good enough, "Road Hazard" and many levy fines for this, its just dangerous to maintain 40 with others 70-75 in a real world of limited access highways.
"Traffic operation and safety characteristics were analyzed in relation to the posting of the minimum speed limit of 40 mph on Florida rural interstate freeways. The operational analysis results showed that 57% of the recorded vehicles exceeded the maximum speed limit. In addition, while only 0.14% of recorded vehicles had speeds below the 40 mph posted minimum speed limit, safety analysis results revealed that 9% of crash-involved vehicles were estimated to have occurred at speeds below 40 mph. The over- involvement of slow moving vehicles in the crash data suggests that even a small proportion of vehicles traveling under 40 mph can have negative impacts on safety. Thus, regulation of vehicle speeds at the lower end of speed distribution is important. Further, the second-order crash risk model developed to estimate the crash risk of a vehicle on the freeway as the function of the deviation from the mean traffic speed indicated that the minimum risk occurred when the pre-crash driving speed is 8 mph above the mean speed, which is equvalent to the 85th percentile speed observed in the field."
That's what I was talking about.
I think this thread has gotten off the intended purpose. It was originally about climbing mountains, and a speed of 40 MPH on long, hard grades. I have been RVing over 40 years, and have seen my share of long grades.
The 85th percentile factor is basically used to determine speed limits on normal city streets and highways. It is definitely appropriate in those uses.
If you drive up ANY long, steep grades you will see any number of types of vehicles going slower than passenger vehicles. The key in this type of situation is to stay in the slow lane except when passing. If necessary, turn on you emergency flashers when legal (trucks do it all the time).
Happy Trails, Forrest