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[Note: This material is copyright by The Gazette, and is reproduced here as a matter of "fair use" for non-commercial, educational purposes only. Any other use may require the prior approval of The Gazette.]

    Officials declined to blame the additional deaths on the higher limit, however, and with good reasons.

    One year is not enough time to detect a trend.

    The statistics do not differentiate between accidents that occurred on sections of interstate where the speed limit was changed and sections where it was not.

    Most of the increase in fatalities occurred during the first six months the limit was higher — 31 in that period compared with 12 in the first six months of the previous year. Yet surveys taken during that time, including those by The Gazette, showed little or no increase in the speeds motorists actually were driving.

    Also, if the dramatic increase in the first six months can be blamed on the new law, how is one to explain the dramatic decrease in the second six months?

    If the nationwide experience is any guide, even a longer period of time under the new Iowa law will not produce a definitive answer, although it will produce numbers that both sides of the argument can use.

    Opponents of higher limits point to reports from the National Highway Transportation Safety Administration showing deaths on interstates increased by several thousand in the decade after the federal government dropped the mandatory 55 mph limit in 1995 and most states immediately increased it.

    Proponents, however, say the same reports show the increase is because of increased travel by Americans, and the death rate has gone down. The two lowest rates since records have been kept were in 2004 and 2005, under 1.5 deaths per 100 million miles driven.

    Moreover, speed is only one of many factors that can contribute to accidents. Alcohol was involved in nearly 40 percent of fatal accidents in 2005, and 56 percent of those killed in vehicle accidents were not wearing seat belts.

    The use of cell phones by drivers often is a subject of jokes, but a recent joint study by the National Highway Transportation Safety Administration and the Virginia Tech Transportation Institute shows they are deadly serious. The report found 80 percent of accidents (fatal and non-fatal) involved a driver who was drowsy, using a cell phone, applying makeup, distracted by children or otherwise not fully concentrating on the job at hand.

    It seems reasonable to believe that speed itself, when limited to roads designed for it, poses far less danger than driver behavior. It is more difficult to change behavior than to change the numbers on a sign, but the return is considerably greater.

    Iowans should keep an eye on the numbers and make adjustments in traffic laws, including speed limits, as they appear advisable.

    In the meantime, the state should redouble efforts to educate people on careless driving, driving while impaired and using seat belts — and crack down even harder on the slow learners.