3. Traffic Safety Culture: The role of speed
(Note: In this and the other articles in this issue of the newsletter, we synthesize some of the key findings in the AAA Foundation’s 2007 report, “Improving Traffic Safety Culture in the United States: The Journey Forward,” (2.8 MB, 388 pp.) published in April 2007. We individually reference some of the 22 papers that make up the report. They are indicated by links in parentheses.)
Two decades ago, there was a good chance that someone at a party where alcohol was being served would make a joking reference to driving after having had “a little too much.” Because of a substantial cultural change in the acceptability of such behavior, drunk driving is no longer seen as a laughing matter. By contrast, speeding is still often viewed with a wink and a nod. People routinely boast about how they made “good time” on a long highway trip, or how they kept up with faster traffic on the freeway in the interest of being punctual for an important appointment.
Attitudes toward excessive speed are an area where a change in the traffic safety culture could have a significant effect.
According to many traffic safety experts, speed should be viewed as the single greatest contributing factor to serious crashes. In 2005, the National Highway Traffic Safety Administration reported that speed was a factor in 30 percent of fatal crashes. This is considered a conservative figure, because it depends on investigators having enough information to attribute speed as a factor in the crash—if the driver was charged with speeding, or if the officer on the scene indicated that speeding was a cause. There are many crashes where this is not possible. For this reason, researchers believe speed contributes to a much greater share of crashes, Barbara Harsha and James Hedlund write (“Changing America’s culture of speed on the roads”). Many believe that it is involved in nearly all serious crashes.
Speeding has been a driving behavior that has been resistant to change. In part, that is due to its subjectivity. “Driving too fast for conditions” is the most forthright definition of speeding. How “conditions” are defined, however, is subjective. Nevertheless, in the eyes of law enforcement, speeding is considered a prima facie offense, which can be a matter of , based on road and weather conditions, etc., as opposed to red light running, which is a clear-cut offense.
Speed’s dangers have been documented: increase in travel speed means an increase in rates of serious injury crashes and fatal crashes. Harsha and Hedlund write:
“First, the probability of a crash is approximately proportional to the square of the travel speed. Second, in a crash, injury risk is approximately proportional to the impact forces on a person, which in turn are proportional to the square of the impact speed. These two effects can be summarized in a general rule of thumb: When travel speed increases by 1%, the injury crash rate increases by about 2%, the serious injury crash rate increases by about 3%, and the fatal crash rate increases by about 4% “
Slowing down makes travel safer. Again, from Harsha and Hedlund: “Consider the effect on a street with a speed limit of 35 mph and average travel speed of 40 mph. A reduction of just 2 mph, to 38 mph, is a 5% decrease, so crashes would be reduced by about 10%, serious injury crashes by about 14%, and fatal crashes by about 19%.”
And if a vehicle is traveling faster than the average speed of the nearby vehicles, i.e., there is a large speed differential between lanes of traffic, crash rates rise sharply. “Someone speeding at 80 mph on a road with average speed of 70 mph has about a 31% greater crash risk, 49% greater injury crash risk, and 71% greater fatal crash risk than drivers at 70 mph. Speeding can be dangerous on all roads. In 2004, half of the speed-related traffic fatalities occurred on roads posted at 50 mph or less, and one-fifth occurred on roads posted at 35 mph or less,” according to Harsha and Hedlund.
Speed is especially dangerous to vulnerable road users, pedestrians and bicyclists.
According to National Cooperative Highway Research Program (NCHRP) Report 500 Volume 18: “A Guide for Reducing Collisions Involving Bicycles” (2008), in a study of nearly 7,000 bicycle/motor vehicle crashes over seven years in North Carolina, the data showed that when excessive speed was involved, bicyclists were six times as likely to suffer fatal injuries and twice as likely to suffer disabling injuries as bicyclists in all crashes involving motor vehicles. “Bicyclists are vulnerable road users, and the impact of higher speeds on crash severity is obvious,” the report stated.
Pedestrians face increased injury risk, too. According to a British reported cited by the North Carolina Pedestrian and Bicycle Information Research Center, a pedestrian hit by a car going 40 mph has an 85 percent chance of a fatal injury; at half the speed, the chance of a fatal injury drops to five percent.
Despite its significant role, however, speed enforcement does not receive much emphasis in traffic safety programs. Harsha and Hedlund note the discrepancy in the most recent highway funding bill.
“The SAFETEA-LU highway reauthorization bill contains $29 million for national advertising to support drunk driving and safety belt use campaigns. It contains not one penny for media to support actions to reduce speeding. The federal response seems to mimic the national feeling that speeding is a traffic safety problem in the abstract, but it’s not at the top of the list.”
This ambivalence in addressing speed is reflected in the history and demise of the National Maximum Speed Limit, which congress enacted in 1974, setting it at 55 mph to conserve fuel. Traffic deaths went down as well. Estimates place the number of lives saved due to the lower speed limit at 3,000 to 5,000. But as gas became more plentiful and its price dropped, compliance with the 55 mph limit began to fall until, finally, in 1987, congress raised the cap to 65 mph. In 1995, congress repealed the speed limit entirely and returned speed limit setting authority to the states, with many highways now at 65 mph or 70 mph. Given the widespread phenomenon of traffic traveling 10-15 mph above the posted limit, this has meant actual highway speeds have increased significantly.
One barrier to reducing speeding is the expense of effective enforcement campaigns, which must be well-publicized, of long duration, and consistent in order to be a deterrent. Automated systems are considerably less expensive, but their use is very limited in the U.S. Although studies overseas have concluded that speed cameras reduce traffic crashes, injuries, and fatalities, there are numerous cultural, political, and institutional hurdles to their implementation in the U.S.
One cultural barrier is the value U.S. drivers place on quick trips and fast cars.
“High-speed mobility is dominant in the United States. Very high speeds are allowed on many highways and speed limits are routinely exceeded (Insurance Institute for Highway Safety 2003). The horsepower of the vehicle fleet has increased in recent years, with many vehicles having speedometers that reach 160 miles per hour, twice the highest speed limit. Vehicles are blatantly advertised for their power and performance characteristics (Ferguson, Hardy, and Williams 2003). Most importantly, there is not a sufficiently safe vehicle and road infrastructure for prevailing speeds on the road network (Johnston 2004b).” note Allan F. Williams and Narelle Haworth (“Overcoming barriers to creating a well- functioning safety culture: A comparison of Australia and the United States").
Other political and institutional barriers include concerns about machines conducting enforcement rather than a sworn officer and the potential intrusiveness of tracking systems and speed cameras.
A change in the cultural attitude toward speeding, however, could provide a counterweight for some of these shortcomings.
Haworth suggests to start anti-speeding campaigns in communities where there is already some support and tailoring them to specific locales.
“What’s needed to change the speeding culture in the right direction? What’s needed to make change happen quickly rather than just watching change happen slowly? Two things, acting together: effective campaigns to eliminate speeding in specific locations and situations where public support already exists and can be increased and vigorous leadership at all levels—local, state, and national—to make reducing speeding a high traffic safety priority. Leadership will bring resources; effective campaigns will raise public awareness of speeding and will increase public support for expanding speeding control more broadly. It’s a simple strategy: start with tightly focused targets; apply known methods to these targets to reduce speeds and crashes; publicize these successes and build on them to expand speeding control more broadly.”