Princess Diana and Reduced Traffic Deaths in France and the United States

This summer marks the 20th anniversary of the death of Princess Diana, who died at age 36 years of a ruptured pulmonary vein and a massive intrathoracic hemorrhage from a traffic crash in Paris, France, on August 31, 1997. The horrific event led to extraordinary public grief, as well as inquests highlighting how her limousine chauffeur was three times over the legal alcohol limit for drinking and driving. Additional factors included excessive speeding, the failure to wear seatbelts, and harassment by paparazzi; there were also alleged conspiracies, none of which was subsequently proven. The French Supreme Court ultimately upheld the official report and concluded that her death was caused by the chauffeur driving at excessive speed while under the influence of alcohol. The need for traffic safety went undisputed.¹

Jacques Chirac, the president of France at the time of these events, was sensitive to the tragedy. Moreover, the event had added personal salience because he had been injured himself in a traffic crash years earlier. Chirac did not directly emphasize the death of Princess Diana beyond condolences (a natural omission given the political traps of discussing foreign nationals or criticizing people after death), but he understood the shifts of sentiments nationwide. For example, Chirac made no mention of traffic safety when elected in 1995, before Diana’s death, whereas he declared traffic safety as one of his three top goals during his 2002 reelection. Traffic safety depends on countless people, as well as political support for reinforced attention and empowered authorities.²

Years have passed, and traffic mortality in France now displays a remarkable trend compared with the United States. During the decades preceding Princess Diana’s death, the two countries tracked nearly parallel overlapping patterns of reductions in traffic fatalities (Figure 1).^3,4 In the two decades following her death, however, a further 30% reduction per decade occurred in France compared with a 15% reduction per decade in the United States. The absolute difference equates to 242 076 additional deaths in the United States during the subsequent years (and an additional 5 million surviving with major injuries). Diverse authorities and commentators have speculated on how these savings in France were motivated partially by the death of Princess Diana.^5–7

FIGURE 1—

Trends in Traffic Fatalities for the United States and France: 1977–2015

Source. Data for the United States were obtained from the National Highway Traffic Safety Administration. Data for France were obtained from L'Observatoire National Interministériel de la Sécurité Routière.

The implications for pedestrians are particularly impressive. In the United States, the number of pedestrian deaths decreased modestly, by 1% per decade (5449 in 1996 vs 5376 in 2015). For France, the number of pedestrian deaths decreased substantially, by 28% per decade (987 in 1996 vs 463 in 2015). By 2015, the risk of death for pedestrians was twice as high in the United States as in France (16.7 vs 7.2 per million population annually), equal to an absolute excess of 3062 Americans. The World Health Organization suggests that the savings in lives for France could be explained by both initiation of new policies and reinforcement of old policies.⁸ Of course, the savings may be a coincidence unrelated to the death of Princess Diana: policy changes occurring after the event are not necessarily caused by the event despite being informed by the event.⁹

A different explanation for the relatively high US mortality could be driving distances, because in theory traffic fatality risks would disappear if all people were stationary.¹⁰ In the United States, total vehicle distances traveled increased 13% per decade (2.484 trillion miles in 1996 vs 3.148 trillion miles in 2015). In France, total vehicle distances traveled increased 12% per decade (470.6 billion km in 1996 vs 584.9 billion km in 2015). Naturally, the geographic layout and mobility patterns will never be identical in the two countries; however, these general indicators of total driving distances do not explain the divergent traffic fatality risks in the United States during the years following the death of Princess Diana.

A more compelling reason contributing to the differential mortality is vehicle speed in the United States and France. The maximum speed limit is nearly the same on highways in the two countries (80 mph and 130 km/h, respectively). Both countries have similar vehicle engineering, road technology, and driver education. The United States, however, has no standard limit for urban areas, whereas France has a maximum of 50 kilometers per hour (30 mph) for city streets. Photo-radar speed enforcement is deployed in only 15 US states, but it became widespread in France soon after the death of Princess Diana. Similarly, only 22 states have red light cameras for drivers who fail to stop at intersections, whereas traffic light radar systems were enacted throughout France about a decade after her death.

The second large difference between the United States and France is impaired driving. Criminal arrest data suggest, for example, that drunk driving offenses are twice as common in the United States (3.5 vs 1.6 per 1000 population annually).^11,12 Similarly, autopsy studies show that traffic fatalities are more likely to involve individuals with a blood alcohol level above the legal limit in the United States (33% vs 21%).¹³ The difference is surprising because alcohol consumption is lower in the United States (9.2 L vs 12.2 L per adult annually) and alcohol intoxication is defined by a lower blood alcohol level in France than in the United States (0.05 g/dL vs 0.08 g/dL). One contributing policy difference is random sobriety checkpoints, which are currently illegal in 12 US states but accepted throughout France.

The utilization of protective equipment and practices is another distinction.¹⁴ Overall, 31 US states have repealed universal motorcycle helmet laws, whereas helmets are mandatory for all motorcyclists and moped riders throughout France. Seatbelts are optional for back-seat occupants in 22 states, whereas they are compulsory for all vehicle occupants in France. Cellular telephone bans do not apply to drivers in 36 states (indeed, 11 states have no bans against cellular telephone use by novice drivers), whereas prohibitions are universal for all drivers in France. The use of bicycle helmets is discretionary for adults in both countries, and bicycle fatalities have stayed similarly low in the United States and France (2.5 vs 2.3 per million population annually, respectively).

Americans might learn from the French despite the complex history of each with the British monarchy. Recent years illustrate the significantly different paths followed by the two countries for traffic safety. These changes reflect political leadership and traffic enforcement rather than reductions in mobility or radical new technology. Given that traffic crashes now cause $242 billion in losses to the US economy each year,¹⁵ the patterns now prevailing in France have a potential market value of $100 billion in savings annually for US society. Causality, of course, cannot be proven, and we will never know the repercussions for Americans had Princess Diana died on the streets of New York City.