Former Assistant Administrator and Chief Safety Officer
for the Federal Motor Carrier Safety Administration
Senate Bill 94
Before the Senate Highways and Transportation Committee
June 10, 2003
Chairman Armbruster and members of the Senate Highways and Transportation Committee, thank you for allowing me to testify before your committee. My name is Julie Anna Cirillo. The topic under consideration is one that I have focused on for almost my entire professional career. I recently retired from the United States Department of Transportation (DOT) where I was the Assistant Administrator and Chief Safety Officer for the Federal Motor Carrier Safety Administration. I worked for the DOT for 34 years. The first 31 of these years were spent with the Federal Highway Administration (FHWA) and its predecessor agencies where I was a safety researcher and ultimately the Regional Administrator in Region 9, San Francisco.
I have an undergraduate degree in Mathematics and Physics and a Masters degree in Transportation Engineering. I have chaired and served on several committees for the National Academy of Sciences’ Transportation Research Board and the Institute of Transportation Engineers. I have received a number of awards and honors including the Secretary’s Gold and Silver Medal and the Presidential Meritorius Service Performance Award.
During my tenure as a researcher I conducted a national study on the safety benefits of the Interstate System. As part of that research I reported that the Interstate System saves approximately 8,000 lives per year due to access control, wider lanes, shoulders, and safe operating speeds. In fact the Interstate Highway system experiences accident and fatality rates 2-5 times less than the primary system it replaced.
In 1963 David Solomon first reported the effect of operating speeds on accidents. In his classic research, Solomon reported that deviation from the mean speed of traffic in BOTH the negative and positive direction contributed significantly to the occurrence of accidents. In fact Solomon showed that vehicles traveling 10-15 miles per hour slower than the mean speed of traffic were much more likely to be involved in accidents than vehicles traveling slightly above the mean speed. Solomon presented his results in the now famous “U-Shaped” curve, which relates variance from mean speed to involvement in accidents.
Solomon’s study was conducted on 2 and 4 lane main rural highways. A similar analysis was conducted on the Interstate that has higher operating speeds. The data for this study was collected by 20 State Highway Departments, including Ohio. The analysis showed the same “U-Shaped” curve for Interstate highways and generally lower accident involvement rates, again confirming the safety benefits of the interstate system. The analysis also showed the variance in speeds on the Interstate was between 5-7 miles per hour approximately ½ that of non-interstate facilities.
The National Highway Traffic Safety Administration subsequently contracted with Indiana University to conduct a speed-safety study. This study confirmed the “U-Shaped” curve established by Solomon and the Interstate Study.
Over the years particularly during and following the energy crisis in 1972-73, the issue of speed limits, operating speeds, and safety has remained controversial and many studies conducted by a variety of organizations including the Transportation Research Board have tried to finally put the issue to rest. During all this activity and up to the present time there has been no evidence to alter Solomon’s original finding that variance from the mean operating speed is a major contributor to accidents. In fact, many safety organizations and states, including Ohio, advise drivers to “drive with the flow of traffic”.
Jurisdictions responsible for insuring the safety of the traveling public should not take any action that could result in creating an unsafe situation. Included in these actions is the establishment and enforcement of differential speed limits for passenger cars and commercial vehicles. Adherence to differential speed limits creates a situation where a significant percentage of traffic is operating much slower than general traffic. This is always unsafe.
In addition, differential speed limits may entice commercial traffic to use less safe non-interstate facilities. If this occurs the jurisdiction will experience much higher accident rates because of the inherent safety of the Interstate System.
Before I conclude my presentation, I’d like to call your attention to several facts:
1. Nationally, since 1999 the number of truck related fatalities and the truck fatality rate has decreased even though the total number of fatalities has increased and the fatality rate has essentially stayed the same. In addition, between 70 and 90 percent of accidents involving commercial vehicles and passenger cars, the passenger car is cited as the cause of the accident.
2. You may hear claims that observed increases and/or decreases in accidents and/or fatalities are due to the existence of split or uniform speed limits. The attribution of any change in safety to any speed limit is very simplistic and generally without merit since the most important things affecting safety are traffic volume, access control, uniform design standards and uniform operating speeds. Claims or inferences that decreases in commercial vehicle accidents in any state is due to split speed limits also negates the impact of the very affective commercial vehicle safety programs in the states.
3. You may also hear that in states where there are split speed limits commercial vehicles are cited for exceeding the posted speed limit (usually 55 mph) by 10-15 mph. Commercial vehicle drivers are professionals. They know that operating with the flow of traffic is the safest operating speed. If the average speed of all vehicles on freeways is about 70 mph then commercial vehicles are behaving in a responsible and safe manner, although in violation of the law. In a study by the Transportation Research Board of the National Academy of Sciences found that commercial vehicles were much more likely to violate the speed limit in states where the speed limit was 65 mph.
4. Finally, it is essential to remember that most accidents occur on non-freeway facilities where split speed limits are not an issue.
In summary, traffic operating at or about the same speed, regardless of speed limit, is the safest traffic environment. Jurisdictions should do whatever they can to encourage this operating scenario and should never require the opposite.
Thank you for giving me the opportunity to testify and I would be pleased to answer any questions you may have.