In The Sun's recent coverage of speed cameras in Howard County, it was noted that one study "showed two-thirds of drivers were speeding and 14 percent going more than 11 mph over the speed limit." This much is absolutely certain: Posted speed limits are not set to maximize safety, they are set about 10 mph too low. If safety were the real goal for a speed limit, it would be set at the 85th percentile speed of free flowing traffic under good conditions. Thus, if 14 percent are going more than 11 mph over the posted limit, then the posted limit should be set 10 mph higher than it is. If it were, the accident rate would decline slightly and the smoothness of the traffic flow would be improved (the real key to safety). If two-thirds of the cars are "speeding" then the limit is arbitrarily set at the 33rd percentile speed to deliberately define 67 percent of all drivers as dangerous violators — which is utter nonsense on the face of it.
To see the Michigan State Police material on this, please go to here and open the last link in the list, "Establishing Safe and Realistic Speed Limits." This is a copy of a presentation given a Michigan legislative committee last February. You will also see a link to a printed booklet on the subject which is on the State of Michigan website.
If you want to research these subjects further, you will find a great deal of data from unbiased traffic safety researchers on our website. (Unbiased in this instance means research done by groups that have no financial conflict of interest in the outcome of the research).
James C. Walker, Ann Arbor, Mich.
The writer is with the National Motorists Association and is a frequent visitor to Maryland.