Comparing the fatality risks in United States transportation across modes and over time

This paper analyzes the transportation fatality risk in the United States. The analysis is in two parts. The first part compares the relative risks of the different modes based on data for the decade from 2000 to 2009. The second part is a time-series analysis for each mode using annual data from 1975 to 2010. By almost any measure, transportation is considerably safer now than it was in the mid 1970s. The improvement is especially noticeable for commercial modes such as aviation, railroads and maritime. Even the risks from private highway driving have halved during the past thirty-five years. 2012 Elsevier Ltd. All rights reserved. This paper analyzes the transportation fatality risk in the United States. The analysis is in two parts. The first part compares the relative risks of the different modes based on data for the decade from 2000 to 2009. Using data from an entire decade minimizes any misleading comparisons that might results from using data for a single year. This is because for some modes there are extreme fluctuations in annual fatality counts due to rare catastrophes that can claim tens, and sometimes hundreds, of lives. The second part is a time-series analysis for eachmode using annual data from1975 to 2010. The choice of 1975 as the starting point was primarily determined by data availability. The federal government established a number of transportation safety agencies in the late 1960s and early 1970s and this resulted in an expansion of data collection. The focus on fatalities is primarily motivated by a greater confidence that thismeasure of safety is reportedmore consistently and accurately across modes and time. In general, cross-sectional and time-series comparisons in fatalities are also indicative of differences in non-fatal injuries, illnesses, and property damage. Albeit that the correlation is not perfect. In particular, fatalities are a poor measure of some of the environmental risks associated with the transportation of oil products and hazardous materials. In addition many of the advances in safety in recent decades have focused on “crashworthiness” whereby design changes have been made to increase the survivability of crashes and mitigate the severity of injuries. Consequently it is possible that a reduction in fatalities may be partly compensated for by an increase in the number of injuries. All rights reserved. Often fatality data is problematic for analytical purposes because fatalities are generally few in numbers, and in somemodes occur in very rare multi-fatality events. As a consequence there are often considerable year-to-year fluctuations, and analyses comparing different modes or time periods suffer from large standard errors and poor statistical significance. However, the United States is a large country with an average population in the decade from 2000 to 2009 of 295million. Therefore, while the risks are low, the annual count of fatalities is substantial in most modes. While passenger fatalities in scheduled aviation, passenger rail, ferryboat and bus modes are dominated by rare catastrophes, other classes of fatalities within these modes are characterized by many single-fatality events that are more consistent in number from year to year. Examples include fatalities resulting from on-demand air taxis, private flying, private boating, collisions between trains and vehicles at rail-highway grade crossings and between trains and pedestrians who are trespassing on the tracks. 1. Cross-sectional analysis The analysis in this section is based on calculating an average annual number of fatalities using data for the ten-year period from 2000 to 2009. An Appendix A gives details on the sources of the data.