concurring.
I concur in the majority’s opinion. I write separately to highlight the significant adverse consequences that the Rochester community will experience due to the increased train traffic running through downtown Rochester, and to point out an additional component of the Final Environmental Impact Statement (FEIS) that the Section of Environmental Analysis (SEA) failed to fully explore.
The record makes clear that the Rochester community will be adversely affected as a result of the Surface Transportation Board’s (STB) decision to approve the Dakota, Minnesota & Eastern Railroad Corporation’s (DM & E) proposal to transport coal from Wyoming to the Mississippi River. This decision will bring up to 37 trains a day, some with more than 100 cars, at speeds up to 40 miles an hour, through the heart of the city of Rochester. These adverse consequences would have been best mitigated by bypassing the city. The STB, however, after carefully considering and analyzing the proposed bypass, properly rejected this alternative due to the additional costs imposed by the length of the bypass, the terrain, and the possibility of sinkholes along the route. Rejection of this alternative, however, does not relieve DM & E of its responsibility to mitigate, to the fullest extent practicable, the adverse consequences the Rochester community will experience due to the rehabilitation of the current rail line.
The majority has carefully set forth the adverse consequences that the Rochester community, including the Mayo clinic, will incur as a result of the decision to rehabilitate the existing railway. These include; *557increased wayside noise; increased vibration in homes and businesses near the tracks; increased risk of groundwater contamination in the event of a rah line accident; and increased risk of delay to emergency vehicles. The majority found that these adverse consequences were fully considered in the FEIS. The majority also found, however, that other adverse consequences to the Rochester community were not fully explored and therefore required further study and exposition by the STB. These adverse consequences are increased noise from train horns and the cumulative effect suffered by households experiencing both noise and vibration.2
In my view, there is an additional area in which the FEIS is insufficient. The SEA recommended the construction of two separated grade crossings in Rochester; the first is scheduled to be installed prior to DM & E transporting 20 million tons of coal annually, and the second is scheduled to be installed prior to DM & E transporting 50 million tons of coal annually through the city. Although these crossings will provide some mitigation of the impact of the increased train traffic in Rochester, the FEIS fails to adequately consider the consequences of deferring the construction of these crossings. The rehabilitation of the rail line and the construction of the separated grade crossings will, in and of themselves, adversely affect the city of Rochester through increased noise, vibration, air pollution, and disrupted traffic flow. Therefore, the Rochester community will suffer not only from an increase in train traffic, but also from the three construction projects; first when the track is rehabilitated, second when the first crossing is constructed, and, again, a third time when the second crossing is installed.
I agree that under the National Environmental Policy Act (NEPA) it is the responsibility of the permitting agency to determine what actions should be taken to mitigate the consequences of the adverse environmental impacts of a project, and that “[o]ur role in the NEPA process ‘is simply to ensure that the agency has adequately considered and disclosed the environmental impact of its actions and that its decision is not arbitrary or capricious.’” Ante at 27 (quoting Baltimore Gas & Elec. Co. v. Natural Res. Def. Council, Inc., 462 U.S. 87, 97-98, 103 S.Ct. 2246, 76 L.Ed.2d 437 (1983)). In this instance, the SEA did neither with respect to the impact of deferring the construction of the separated grade crossings. The SEA is required to discuss the reasons why a certain miti-gative step was chosen and the impact of that choice in enough detail to ensure that the environmental consequences are fairly evaluated. Robertson v. Methow Valley Citizens Council, 490 U.S. 332, 352, 109 S.Ct. 1835, 104 L.Ed.2d 351 (1989) (stating that the “requirement that an EIS contain a detailed discussion of possible mitigation measures flows both from the language of [NEPA] and, more expressly, from CEQ’s implementing regulations” and that the “omission of a reasonably complete discussion of possible mitigation measures would undermine the ‘action-forcing’ function of NEPA.”). In this case, the SEA asserted that the construction of two separated grade crossings will mitigate the impact of the increased train traffic in Rochester, but failed to discuss how it decided on two *558rail crossings, or to consider the impact of deferring the construction. It is not enough to put forth installing such crossings as appropriate mitigation without revealing the reasoning behind such a finding, or detailing the impact the proposed mitigation will have on the community. Instead, the SEA is required to “explain fully its course of inquiry, analysis and reasoning.” Ante at 31 (quoting Minn. Pub. Interest Research Group v. Butz, 541 F.2d 1292, 1299 (8th Cir.1976)).
I cannot say, based on the FEIS developed by the SEA, that it took the requisite “hard look” at the environmental impact of rehabilitating the current railway on the Rochester community. Fully analyzing alternatives is the “heart of the environmental impact statement,” 40 C.F.R. § 1502.14, and the agency is required to “Vigorously explore and objectively evaluate all reasonable alternatives,” 40 C.F.R. § 1502.14(a). Although I agree with the majority that the STB adequately considered and properly rejected the proposed bypass of the city of Rochester, the STB failed to sufficiently detail the mitigation measures that should be taken. This omission undermines the action-forcing function of NEPA.
The adverse consequences that the Rochester community will suffer due to this project are severe. The STB, therefore, should be required to consider the adverse consequences outlined in the FEIS and discussed by this court, both individually and collectively, in order to fully analyze all possible steps that can be taken to mitigate their impact on the Rochester community.
. I agree with the majority’s holding that the reasonably foreseeable effects of increased coal consumption in Midwestern and Eastern states also must be thoroughly considered. Even though there is no evidence in the record that the Rochester community will be adversely affected by any significant increase in coal consumption, the environmental consequences of such an increase to other geographic areas should be considered by the STB.