LIGHTNING SAFETY AND LARGE STADIUMS BY JOEL GRATZ AND ERIK NOBLE Many stadium managers do little to anticipate or control the threat of lightning when large crowds gather. e attended a University of Colorado football game at Denver’s Invesco Field on Saturday, 20 August 2003. For this W highly contentious game between intrastate rivals Colorado State and the University of Colorado, Invesco Field provided a neutral site and the capacity to accommodate large crowds. The official stadium attendance for that night was 76,219 people. During the third quarter, lightning lit up the southern sky as heavy rains blanketed the stadium. A public address announcement stated that the game was suspended due to lightning, A lightning strike was photographed near Virginia Tech’s Lane Stadium. See figure 2 on page 1192 for more details. AMERICAN METEOROLOGICAL SOCIETY SEPTEMBER 2006 | 1187 and all players, coaches, and stadium personnel Given that real-time lightning monitoring systems on the field immediately ran for cover. During the are widely available and there is general agreement 30–45-minute delay, stadium management did concerning locations and procedures that substan- not provide any instructions to spectators. Many tially reduce the lightning threat, stadium managers crowded the exit ramps and concourses to escape can take proactive steps to mitigate the risks posed by the downpour, while others remained in their seats lightning rather than embrace the false assumption during the storm. The game eventually resumed with that no specific lightning policy can anticipate/con- no reported injuries to players or spectators result- trol the threat. In this article we will do our best to ing from the storm. Yet, we wondered why the event connect what is known about existing lightning pro- managers gave no direction to protect the 76,219 tection technology and crowd management strategies spectators from the dangers of lightning. to recommend guidelines for the enhanced safety of A review of lightning casualty cases identified the large number of spectators that attend events in a woman who was struck as an off-field spectator outdoor stadiums. Numerous other weather events at a concert held in Washington, D.C.’s, Robert F. could pose a hazard to stadium occupants (for more Kennedy (RFK) stadium on 6 June 1998 (Milzman about the close call of a 2005 tornado threatening an et al. 1999). Stadium officials evacuated more than Iowa State football game, see the sidebar on pages 4 50,000 spectators shortly after that strike. This event and 5), and we recommend that stadium managers demonstrates the reality that lightning can strike and consider the risk of tornadoes and hail in addition to injure spectators in outdoor stadiums. Furthermore, the threat of lightning covered in this article. experiences at Invesco Field and RFK stadium reveal a lack of consensus and expertise when dealing with lightning safety pro- cedures for large numbers of spectators. Large outdoor stadi- ums face a significant vul- nerability to lightning. To date, there have been few casualties in the United States from direct light- ning strikes to a stadium or from the mass movement of spectators when light- ning threatens. However, if stadium managers do not develop action plans for lightning safety, venues are FIG. 1. Average density of lightning strikes over 5 years. Strike density is mea- sured in strikes per square kilometer per year. Black numbers (1–25) denote overlooking an opportu- the 25 largest National Collegiate Athletic Association (NCAA) Division I nity to prevent a potential football stadiums based on average per game attendance for the 2005 season. disaster while the costs of Table 1 provides more information on each school. Although the base map is intervention remain sub- made from older data, these were the best-calibrated data available at the stantially low. time of publication (base map courtesy of Vaisala 2005). AFFILIATIONS: GRATZ—Center for Science and Technology Policy E-mail: [email protected] Research, CIRES, and MBA Program, Leeds School of Business, The abstract for this article can be found in this issue, following the University of Colorado, Boulder, Colorado; NOBLE—Center for Sci- table of contents. ence and Technology Policy Research, CIRES, Boulder, Colorado DOI:10.1175/BAMS-87-9-1187 CORRESPONDING AUTHOR: Joel Gratz, Center for Science and Technology Policy Research, CIRES—University of Colorado, 1333 In final form 20 January 2006 Grandview Ave., Campus Box 488, Boulder, CO 80309-0488 ©2006 American Meteorological Society 1188 | SEPTEMBER 2006 IS LIGHTNING A DANGER TABLE 1. The 25 largest NCAA Division I football stadiums by TO STADIUMS? Because col- average game attendance for the 2005 season. lege football has many of the largest Average attendance stadiums in the United States, Fig. 1 Rank School per game uses these stadiums to visualize the lightning threat to large outdoor 1University of Michigan110,915 stadiums in general. This graphic 2 University of Tennessee 107,593 depicts the location of the top 25 3 Ohio State University 105,017 stadiums with the highest average 4 The Pennsylvania State University 104,859 attendance on a base map of average 5 University of Georgia 92,701 annual lightning strikes during the 5-year period from 1996 to 2000. 6 Louisiana State University 91,580 Each stadium is described further 7 University of Southern California 90,612 in Table 1. The area of the greatest 8University of Florida90,406 lightning frequency is generally 9University of Oklahoma84,331 collocated with the largest collegiate 10 Auburn University 84,161 stadiums across the central and southern sections of the United 11 University of Texas 83,333 States. Although the statistical threat 12 Florida State University 82,724 of a lightning strike (cf. Krider and 13 University of Wisconsin 82,551 Kehoe 2004) within a stadium is 14 University of Alabama 81,018 very low, Fig. 1 should at least serve 15 University of Notre Dame 80,795 as a qualitative warning to stadium managers that large outdoor events 16 University of South Carolina 79,867 often occur in the areas of the most 17 Texas A&M University 79,732 frequent lightning strikes. 18 Clemson University 78,417 In addition to the theoretical 19 University of Nebraska 77,485 warning to stadium managers in 20 Michigan State University 75,183 Fig. 1, an empirical warning also ex- ists. Just in the past few years, light- 21 University of Iowa 70,585 ning impacted the college football 22 Virginia Tech 65,115 games listed in Table 2, with a com- 23 University of Washington 64,326 bined attendance of over 500,000 24 University of California, Los Angeles 64,218 fans. Thus, the lightning threat is 25 University of Arkansas 63,678 both theoretical and real, and should not be pushed aside. Although large stadiums pose safety challenges due to their size, TABLE 2. Recent Division I college football games that were crowd density rather than crowd delayed by lightning. Numerous other events in outdoor stadiums size is the overwhelming concern were delayed by lightning and this list should only be considered in lightning safety policies. If a sta- an example of the true impact of lightning on large stadiums. dium is relatively empty, it is easier Percent of Date Location Attendance for spectators to move quickly to capacity shelter. But, in the case of the seven 18 Sep 2004 University of Arizona 50,111 86.7% events listed in Table 2, the stadiums 4 Sep 2004 Louisiana State University 91,209 99.6% were filled near to or over capacity resulting in a situation where mass 27 Sep 2003 University of Alabama 83,189 99.3% crowd movement is difficult and 14 Sep 2002 University of Florida 85,185 102.6% even dangerous. In fact, the National University of South 14 Sep 2002 82,138 102.4% Fire Protection Association’s guide- Carolina lines for lightning protection lists the 14 Sep 2002 University of Oklahoma 75,104 103.2% “risk of pannic . ” as the number 1 Aug 2000 Virginia Tech 56,272 112.5% one safety concern for large venues AMERICAN METEOROLOGICAL SOCIETY SEPTEMBER 2006 | 1189 (NFPA 2004). Therefore, stadium managers should that most people rely upon to assess the lightning acknowledge not just the physical threat of a direct threat may be obscured by crowd noise or impeded lightning strike, but also the crowd management is- by the stadium structure and the stadium lighting. sues of trampling and bottlenecks in crowd flow that Therefore, it is the responsibility of stadium manage- could pose a greater threat to spectator safety. ment to monitor any lightning activity and have an In addition, because spectators will still attend appropriate action plan in place. an event with thunderstorms in the forecast, event managers should take on the responsibility for en- CURRENT LIGHTNING PROTECTION suring spectator safety because most spectators enter STRATEGIES. Guidelines do exist that can aid the stadium and surrender any access to real-time stadium managers to establish an effective light- warnings of thunderstorms [with the exception of the ning action plan, but sometimes officials do not minority of spectators with wireless weather access develop plans until after an incident occurs. During via a cell phone/personal digital assistant (PDA)]. a football game on 27 August 2000, a thunderstorm Although some fans might use radios that provide produced 12 lightning strikes within one mile of the commentary on the game and may also provide center of Virginia Polytechnic Institute and State weather warnings, the usual audible and visual clues University’s (Virginia Tech’s) Lane Stadium, with “CYCLONE” THREATENS CYCLONE GAME —William A. Gallus Jr. Iowa State University, Ames, IA 50011 he last home football game each TNovember at Iowa State University (ISU) is usually a time where fans and officials alike worry about snow and cold.