On June 24, 2005, 11 years after Congress directed the Federal Railroad Administration (FRA) to issue a regulation on the sounding of train horns at grade crossings, FRA's Rule on the Use of Locomotive Horns at Highway-Rail Grade Crossings took effect. The train horn rule requires that locomotive horns be sounded at all public highway-rail grade crossings, except where there is no significant risk to persons, where supplementary safety measures fully compensate for the absence of the warning provided by the horn, or where sounding the horn as a warning is not practical. The rule implemented a congressional mandate in Title III, Section 302, of P.L. 103-440 (codified as 40 U.S.C. 20153). FRA exempted the Chicago region from the rule, pending a re-analysis of grade-crossing accident data for that area. The Chicago area includes 45% of the nationwide population FRA estimated to be potentially affected should pre-existing bans on sounding train horns at road crossings ("whistle bans") be eliminated as a result of this regulation. The FRA train horn rule preempted roughly 2,000 existing state and local whistle bans. The rule allows communities to establish "quiet zones" where the sounding of locomotive horns can be banned, provided that the risk of grade-crossing collisions is below a certain level or that the community provides safety measures that compensate for the absence of the warning provided by the train horn. In some cases communities may establish quiet zones without making any safety improvements; in other cases, communities will be required to make safety improvements to grade crossings in order to obtain FRA approval to establish a quiet zone. The United States has approximately 250,000 highway-rail at-grade crossings. Collisions at these intersections are typically responsible for nearly 40% of all railroad-related deaths. The vast majority of grade-crossing collisions are caused by motorists, and the vast majority of injuries and deaths resulting from these collisions are experienced by motorists. Reducing the number of injuries and deaths resulting from grade-crossing collisions has been a federal concern for decades. Congress has provided more than $4.1 billion since 1974 specifically for grants to states to reduce the risks of grade crossings, and reducing risks at public grade crossings is an eligible expense under several federal highway funding programs. This funding has resulted in the installation of around 30,000 active warning devices at grade crossings, and the closing of many other crossings, since 1974. Both the number and rate of incidents and deaths at grade crossings have declined significantly over time. Between 1994 and 2003, the decade prior to publication of the FRA interim final rule, the number of annual highway-rail grade-crossing incidents fell from 4,892 to 2,909 (-41%), and the annual number of deaths in these incidents fell from 626 to 325 (-48%). These decreases occurred in spite of growth in both train and auto traffic. According to the Inspector General of the Department of Transportation, the primary sources of the reduction in grade-crossing collisions in the decade prior to the new rule were the permanent closing of about 41,000 grade crossings and the installation of active warning signals (flashing lights and automatic gates) at about 4,000 grade crossings. The number of deaths from grade-crossing collisions has declined by around 30% since the train horn rule took effect, from 358 in 2005 to around 250 annually since 2009 (see Figure 1 ). There has also been a significant decline in most other types of highway deaths since 2005. The number of vehicle miles traveled each year has fallen due to high gasoline prices and a sluggish economy. It is not certain that the recent decline in grade-crossing deaths will persist if driving activity resumes its historical growth rate. The train horn rule was prompted by industry consolidation since the 1980s, which led to a reduction in railroad track mileage and heavier use of the remaining network. The increasing number of train movements on lines that remained in use, combined with growing sensitivity on the part of communities toward noise levels in the environment, resulted in a number of communities banning the sounding of train horns at intersections. In 1984 the state of Florida authorized local communities to ban the sounding of horns by intrastate railroads at night at intersections equipped with flashing lights and bells, crossing gates, and signs warning motorists that trains' horns would not be sounded at night. By 1989, Florida communities had banned the nighttime use of train horns at 511 of 600 eligible intersections. A 1990 FRA study found that there were almost three times as many collisions after the bans were established, while the daytime collision rates were virtually unchanged. FRA concluded that banning the sounding of train horns at grade crossings created a safety risk. The agency issued an emergency order in 1991 ending train horn bans in Florida. In the two years after that order, night-time collision rates dropped to near pre-ban levels. The Florida study led FRA to do a similar nationwide study. That study, published in 1995, identified 2,122 public grade crossings where train horn bans had been in place at some time between 1988 and 1994 (not counting the 511 crossings in the Florida study). It concluded that crossings with train horn bans "averaged 84% more collisions than similar crossings with no bans." In response to the evidence of increased risk of injuries and death from bans on the use of train horns at intersections, Congress increased the availability of federal funding to install automatic warning gates at crossings. In FY2000, for example, the Federal Highway Administration (FHWA) made $155 million available specifically for grade-crossing safety, and an additional $368 million of federal highway safety funding was available for states to use on grade-crossing improvements, at their discretion. In addition, in 1994 Congress mandated that FRA regulate the use of train horns at intersections, requiring their use except in certain situations at FRA's discretion. FRA's 2005 train horn rule implemented that congressional mandate. FRA describes the rule as "a safety rule that implements as well as minimizes the potential negative impacts of a Congressional mandate to blow train whistles and horns at all public crossings." It requires that locomotive horns be sounded at public highway-rail grade crossings, while providing exceptions to this requirement. The regulation preempts state and local train whistle bans. The rule did not establish a new safety standard. FRA noted that prior to publication of the rule, train horns were already being sounded at more than 98% of public grade crossings; thus, the rule formalized an already prevailing industry standard. The majority of the text of the rule deals with exceptions to the requirement that train horns be sounded at all public grade crossings, and particularly with procedures for establishing quiet zones. The terms of the exceptions are intended to balance the risk of removing one safety measure (the sounding of the train horn) by adding other safety measures. However, under some circumstances communities can ban the sounding of train horns at grade crossings without additional safety improvements, where adequate safety features are already in place or where the risk of accidents is below one of the thresholds established in the regulation. In permitting exceptions to the law requiring the sounding of train horns at crossings, FRA sought "to ensure that quiet zones, while providing for quiet at grade crossings, also continue to provide the level of safety for motorists and rail employees and passengers that existed before the quiet zones were first established, or in the alternative, the level of safety provided by the average gated public crossing where locomotive horns are routinely sounded." Thus, the rule seeks to compensate for the risk that silencing train horns at grade crossings will lead to additional train-vehicle collisions by generally requiring additional safety measures. The minimum requirement for a quiet zone is that every public highway-rail grade crossing in the proposed quiet zone corridor must have flashing lights and gates that control traffic over the crossing. There are three alternatives available to a community wanting to establish a quiet zone: The community can institute supplementary safety measures at each public crossing in the quiet zone. These measures, specified in the rule, physically reduce the risk of motorists being involved in a collision with a train at a grade crossing. They may include closing the crossing to highway traffic permanently or during the hours when the whistle ban is in effect; making it more difficult for motorists to drive around a lowered gate by blocking approach lane(s) to the crossing; installing a four-quadrant gate system such that gates block both approach and departure lanes from the crossing; or installing a median that prevents a motorist from swerving out of an approach lane that is blocked by a lowered gate. If the accident risk for the quiet zone is less than or equal to the national average risk of accidents at grade crossings equipped with flashing lights and automatic gates where train horns are sounded, known as the "Nationwide Significant Risk Threshold," the community can establish a quiet zone without implementing additional safety measures. Otherwise, the community must use alternative measures to reduce the level of risk to the national average, including a systematic program of monitoring and enforcing traffic laws at crossings; a public education and awareness campaign about the risks of grade-crossing accidents; photo enforcement; or any of the supplementary safety measures specified above. The community can implement safety measures that reduce the risk of grade-crossing collisions in the quiet zone, as measured by an FRA index, to no more than the level of risk prior to creation of the quiet zone. Quiet zones that are qualified by the second criterion, comparison to the national average risk of grade-crossing accidents, must be reviewed each year. The average itself is recalculated each year, so a quiet zone that qualified by having a risk below the nationwide average may fall out of compliance if the nationwide average declines. In such a case, a community would be required to implement additional safety measures or to eliminate the quiet zone. Communities may get a proposed quiet zone approved in two ways. The quiet zone may qualify for automatic FRA approval, without detailed review, if it meets the first or third condition listed above.