The Effect Of A National Speed Limit On Traffic Safety & Fuel Prices

By James Baxter, NMA President

In 1982 Congress authorized the National Academy of Science to do a study that documented the “benefits” of the 55 MPH National Maximum Speed Limit (NMSL).

I, as the President of the organization most critical of the national speed limit, was considered as a potential member of the advisory panel to oversee and guide this study.

This invitation was withheld and never offered because it was determined (by an unknown someone) that political advocates would not be seated on the Advisory Panel. In exchange, I was offered the opportunity to present testimony to the Advisory Panel and Transportation Research Board staff responsible for the national speed limit study.

While my testimony covered a wide range of subjects I specifically attacked the premise that the 55 MPH NMSL was responsible for reducing highway fatalities by 17 percent (from 55,000 to 46,000 traffic related deaths). I pointed out that many of those reductions took place on roads and streets with speed limits that were never higher than 55 miles per hour. Even those fatal accidents that did take place on highways with higher speed limits were often in no way related to speed or speed limits.

My main premise was that the combination of a distressed economy, embargo related fuel shortages, and escalating fuel prices drastically reduced discretionary travel and that is why fatalities dropped in the manner they did.

My apolitical detractors on the Advisory Panel (like former heads of NHTSA and insurance industry representatives) were quick to point out that miles traveled only declined two to three percent, so surely reduced travel could not account for 9000 fewer fatalities in 1974. However, subsequent investigation by the TRB staff ultimately determined that estimates of vehicle miles traveled are riddled with inconsistencies and contradictions. (They remain so today.)

In the end, the authors of the “55” study concluded that the reduced speed limit was responsible for somewhere between 2000 to 4000 of the fewer fatalities (a number dutifully reported by U.S. Senator Warner during a recent press conference promoting the reincarnation of a national speed limit). This number was little more than a politically expedient guess.

Fast forward to July 2008, the economy is in distress, fuel is readily available but very expensive, and traffic-related fatalities are plummeting.

The big missing ingredient is that there is no national speed limit to take the credit.

Furthermore, while travel speeds have decreased, the decrease is very moderate — approximately an average of one mile per hour according to our home state (Wisconsin) highway patrol. Highway fatalities are 30 percent behind those of a year ago for the same time period, in the same state.

There’s the usual official claptrap about stepped up speed enforcement, DUI arrests, and restrictions on teen driving, all of which were equally in play last year and the year before that. The bottom line is that discretionary travel has tanked and with it some of our highest risk driving. This trend will continue until the economy recovers and/or household fuel bills decline.

Fuel prices are likely to remain high, at least in the near term and probably beyond that. However, individual strategies intended to reduce fuel use will reduce household fuel bills. To the extent that these strategies reduce travel we will see commensurate fatality reductions. Those strategies that simply make travel less expensive, e.g. buying a more efficient vehicle, will increase travel and most likely they will result in increased traffic related fatalities. The good news is that long term trends indicate reduced highway fatality rates, primarily because of better vehicles and improved highways.

Political gimmicks, like 55 MPH national speed limits, will not improve highway safety, reduce fuel prices, or have a meaningful effect on fuel supplies. All they do is generate red tape, traffic tickets, and auto insurance surcharges.

Keep that in mind the next time you hear some self-appointed “expert” touting a national speed limit.

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