The opinion of the court was delivered by: SOFAER
ABRAHAM D. SOFAER, UNITED STATES DISTRICT JUDGE
On January 19, 1981, the United States Department of Transportation ("DOT") published a "Final Rule" concerning the transportation of radioactive materials pursuant to its authority under the Hazardous Materials Transportation Act ("HMTA"), 49 U.S.C. §§ 1801-1812 (1976). The rule, scheduled to take effect on February 1, 1982, would permit the shipment by road throughout the nation of all types of radioactive materials. One avowed purpose of the rule was to override local prohibitions against the shipment of radioactive materials, particularly a local regulation adopted by the Board of Health of New York City ("City") on January 15, 1976. The City commenced this action on March 25, 1981, seeking to invalidate DOT's rule or, at least, to prevent it from overriding the City's regulation. The State of New York intervened as a plaintiff, moving for discovery and a preliminary injunction against enforcement of DOT's rule within the State's borders; the Town of Brookhaven and Sullivan County, New York, and joined the City and State's efforts. The United States has been joined in its defense of DOT's rule by numerous intervening power companies as well as by several amici curiae.
Plaintiffs seek relief on numerous grounds. Several are meritless. Indeed, the welter of arguments contained in plaintiffs' papers tends to obscure the fact the DOT's actions are challenged meaningfully only insofar as they relate to the highway transportation of spent fuel from nuclear reactors and other large-quantity shipments of radioactive materials through densely populated areas such as New York City. In all other respects, the administrative record and the law supports DOT's Final Rule.
Insofar as DOT's actions require states and localities to permit the highway transport of spent fuel and other large-quantity shipments through densely populated areas, the record developed by DOT cannot justify the challenged rule. The agency has failed to fulfill its responsibilities under the National Environmental Policy Act ("NEPA"), 42 U.S.C. §§ 4321-4361 (1976), and under the regulations promulgated under NEPA by the Council on Environmental Quality and by DOT itself. In particular, DOT has failed adequately to evaluate and to address itself to the problems posed by low-probability/high-consequence occurrences that are concededly "credible." NEPA requires that an agency confronted with these problems, fundamental in a society dependent on inherently dangerous technologies, conduct a thorough examination and make determinations that are susceptible to review concerning: (1) the probability of the occurrence contemplated; (2) the potential consequences of such an occurrence; and (3) the environmental risk reflected by the probability and the consequences estimated. Because its environmental evaluation is deficient in all three respects, DOT's Environmental Assessment is inadequate, and DOT's finding that its action will have no significant environmental impact and therefore that no environmental impact statement need be prepared -- is insufficiently supported by the present record. Furthermore, DOT has failed adequately to consider alternatives to highway transport that might reduce or eliminate the risks posed to urban areas by low-probability/high-consequence accidents or by malevolent acts. Even if DOT could lawfully choose to regulate only highway transport at this time, it cannot rationally evaluate the option of taking no action without examining at least superficially the availability of nonhighway modes to accommodate shipments prevented by local and state laws from crossing densely populated areas. DOT has therefore failed to perform its obligation to "study, develop, and describe" appropriate alternatives.
Apart from DOT's obligation under NEPA to evaluate more fully the environmental consequences of its proposed rule, HMTA imposes similar duties on DOT and in addition sets limits on the agency's authority to deem certain risks acceptable. For the same reasons DOT's analysis is invalids Under NEPA, its adoption of the challenged rule was an arbitrary and capricious exercise of its rulemaking authority under HMTA: DOT inadequately considered the risks of highway transport and the need, given potential alternatives, to impose those risks on the public. Further, DOT erroneously concluded that it is free under HMTA to subject unwilling states and localities to risks of potential catastrophe that DOT itself deemed "credible" and "important" when those risks are avoidable. HMTA mandates that in exercising its regulatory power DOT avoid where reasonably possible all significant risk not inherent in the transportation of hazardous substances. In adopting a new rule covering the transportation of spent fuel and other large-quantity radioactive materials, DOT must be guided by Congress policies, not by its own perception of acceptable risk. On the present record, DOT's regulation is unreasonable in light of the properly applicable legal standards.
The Court's role in this case is to conduct a "searching and careful" review of DOT's actions, but only in order to determine whether the agency has acted reasonably in fulfilling its statutory obligations. Citizens to Preserve Overton Park, Inc. v. Volpe, 401 U.S. 402, 416 (1971). The nature of contemporary scientific disputes requires a court to give close attention to detail, to ensure that it neither fails to perform its duty of careful review, nor goes beyond its limited role because of any failure to give proper weight to all the evidence supporting the agency's judgment. A full review of the record is therefore necessary to identify all the evidence actually considered or implicitly supporting DOT's conclusion. After that review the opinion examines plaintiffs' numerous contentions.
I. Factual Background for DOT's Action
One of the problems created by the use of radioactive materials in American medicine and industry is the need to transport them. Our society is highly dependent on radioactive materials. In medicine, gamma-ray-emitting isotopes are commonly used to image specific areas and organs of the body. Radioisotopes of iodine are used to diagnose and treat thyroid disorders; other isotopes are used in millions of scanning procedures annually. Large quantities of Co-60 (cobalt) or Cs-137 (cesium) are used for cancer treatment, research, and large-scale food sterilization. Well-logging firms use radioisotopes to assess a well's capability; radioactive tracers are also used for this purpose. The radiography industry uses certain isotopes that emit high-energy gamma rays to examine the structural integrity of welded joints, particularly in large pipes and frames.
Radioactive materials are especially effective in a large variety of guaging applications. And, of course, the nuclear power industry uses radioactive materials, and generates large quantities of irradiated (spent) fuel. All of these uses require transport to one degree or another, often at several different stages, including manufacture, use, and disposal.
As the use of radioactive materials has become increasingly common, public awareness of the dangers posed by their transportation has heightened. Since the middle of the 1970s, governmental authoritites on federal, state, and local levels have begun to address the problem. In 1975 Congress passed HMTA to centralize authority in DOT to promulgate and enforce regulations to protect the public against "the risks to life and property which are inherent in the transportation of hazardous materials," including radioactive materials. 49 U.S.C. § 1801 (1976). The act specifically empowers the Secretary of Transportation to issue routing rules for the safe transportation of radioactive materials. Id. § 1804(a). Congress provided expressly for the preemption of state and local rules inconsistent with the act or with regulations adopted under it, except for inconsistent rules that DOT finds ensure equal or greater public safety than the inconsistent federal requirements and do not unreasonably burden interstate commerce. Id. § 1811.
DOT regulations that preexisted the passage of HMTA required motor vehicles containing hazardous materials to use routes that "do not go through or near heavily populated areas, places where crowds are assembled, tunnels, narrow streets, or alleys," unless "there is no practicable alternative." 49 C.F.R. § 397.9(a) (1980). Every vehicle containing hazardous materials was required to comply with local driving and parking laws, unless the local laws were at variance with a more stringent rule imposed by DOT; and state or local laws governing transport through vehicular tunnels used for mass transportation were specifically exempted from any arguable preemption. 49 C.F.R. §§ 177.810, 397.3 (1980). These regulations continued in effect after HMTA's adoption in 1975.
The Final Rule challenged in this proceeding is the direct result of DOT's determination to deal with the disruptive effects of a health regulation, adopted on January 15, 1976, by New York City's Board of Health as an amendment to its Health Code, prohibiting the commercial transport into or through the City of large-quantity or high-level radioactive materials. N.Y.C. Health Code § 175.111(1). Complaint of New York City, Ex. A.
The amendment effectively prevented the Brookhaven National Laboratories ("BNL") from shipping spent nuclear fuel from Long Island through densely populated areas of the City by truck. In addition the regulation would prevent shipments of spent fuel and other material from traveling through the City from the Shoreham Nuclear Unit, expected to begin operating in 1983. On the very day that the City adopted the regulation, the federal government sued to have it declared preempted and unenforceable. Judge Inzer B. Wyatt denied preliminary relief on January 30, 1976, and the case was subsequently transferred to the suspense docket by stipulation. United States v. City of New York, 76 Civ. 273 (IBW). On March 1, 1977, Associated Universities, Inc., consisting of nine institutions whose representatives formed the BNL Board of Directors, sought a declaration from DOT that the City's regulation was inconsistent with HMTA and with DOT regulations. DOT denied the request on April 20, 1978, ruling that the City regulation was in effect a routing requirement and that, although DOT had the power to preempt local routing rules, the agency had not yet exercised that power. DOT recognized that the City had adopted its regulation because its public health officials had considered that, given the City's dense population, "the consequences of a major accident are too extreme to be tolerable, however remote the probability." 43 Fed. Reg. 16954, 16957 (1978). Even so DOT suggested that it disapproved of the City's regulation. Id. at 16957-58. Since 1976 BNL has shipped spent fuel by water, via New London, Connecticut, although that option may recently have been made unavailable by local law.
On August 17, 1978, DOT invited comment "on the need, and possible methods for establishing routing requirements under the Hazards Materials Transportation Act applicable to highway carriers of radioactive materials." 43 Fed. Reg. 36492 (1978). The "advance notice" made clear that it was motivated in particular by the fact that the City had prohibited highway transport of most commercial shipments of radioactive materials. It noted that other jurisdictions had adopted safety requirements imposing "significant additional responsibilities on shippers, carriers, or neighboring jurisdictions," all of which "affect interstate commerce." The notice proposed to examine the safety aspects of highway transport and the effects of existing regulations. Most significantly, DOT announced at that time that it intended to limit its consideration to highway routing, and would not consider alternative modes:
Only highway routing of radioactive materials will be considered in this docket. This does not rule out the possible future consideration of materials in other hazard classes and other modes of transportation. However, highway transportation, of all four modes of transportation, offers the largest number of routing possibilities and the greatest access to population centers.
Id. at 36492. The notice referred the public to several studies, including most notably the Final Environmental Statement on the Transportation of Radioactive Material by Air and Other Modes ("NUREG-0170") prepared for the U.S. Nuclear Regulatory Commission ("NRC") in December 1977. It also noted DOT's intention to consider the results when available of NRC's study, then underway, of transport through urban areas, eventually published as Transportation of Radionuclides in Urban Environs: Draft Environmental Assessment (NUREG/CR-0743; SAND 79-0369) (1980) ("SANDIA"). Finally, the notice flatly asserted that, although its prior regulations left control of highway traffic of hazardous materials primarily to state and local regulation, those regulations reflected "the principle that such State and local regulation should not have the actual effect of altogether forbidding highway transportation between any two points, even where other modes of transportation are available." 43 Fed. Reg. at 36493. DOT did not explain how it derived this principle, although DOT had itself ruled that the City's regulation was consistent with federal law and with its own regulation, 49 C.F.R. § 397.9(a) (1980), requiring compliance wherever "practicable" with local rules that mandate avoidance of heavily populated areas. 43 Fed. Reg. at 16954.
DOT scheduled a public hearing on its notice. The Director of the City's Bureau of Radiation Control, Dr. Leonard R. Solon, submitted a statement proposing that DOT not limit itself to considering only highway transport. Dr. Solon suggested that barging spent fuel was feasible and that DOT should enlist the assistance of the Coast Guard and Department of Energy to develop plans for maritime transport. Solon Affidavit para. 11, New York City Notice of Cross-Motion for Summary Judgment [hereinafter "City Motion"] "This would minimize the public health risks of spent fuel transportation by bypassing populated areas." City Motion, Ex. B at 11. In addition, DOT's proposed rulemaking was specifically noted in the Report to the President by the Interagency Review Group on Nuclear Waste Management (March 1979) ("IRG Report"). Responding to the concerns of a highway-carrier representative regarding state and local restrictions, and of state and local officials regarding transportation through or near populated areas, the IRG Report stated that DOT's rulemaking was an important step towards resolution of the issues. Although comments received by the IRG said that there was a special need for DOT to resolve the highway routing question, id. at 113, the IRG, consistent with its comments on NEPA's requirement that alternatives be considered, id. at 21-22, articulated a broader view:
DOT should proceed expeditiously to examine the desirability of Federally prescribed routing requirements for one, rail, and highway shipment of radioactive wastes, as well as the question of to what degree local restrictions are appropriate.
Id. at 112 (emphasis added).
A. DOT's Notice of Proposed Rulemaking
On January 31, 1980, DOT published its proposed rule for the highway routing of radioactive materials, as well as a draft environmental assessment. 45 Fed. Reg. 7140 (1980). The agency again reviewed the history of New York City's regulation and concluded that national action was necessary to prevent local and state rules from interfering with radioactive shipments by highway. The notice summarized accident data and, relying on NUREG-0170 and on the Sandia Laboratory's draft report Transport of Radionuclides in Urban Environs: A Working Draft Assessment (May 1978), DOT concluded that the "estimated risks" from both accident-free highway transport and accidents "are within the magnitudes of other socially accepted risks, such as evidenced in highway traffic fatality rates." The agency noted the public concern over highway transport of radioactive materials, but found it unjustified by the estimates:
Public concern with radioactive materials transportation, however, is more profound than those estimates would suggest is justified. In part this concern reflects the distinction between risks which are likely to be concentrated and similar risks spread over differing times and locations. The annual death rate from passenger car accidents, for example, usually is perceived as less catastrophic than major aircraft accidents, although far more people die in automobile accidents. This distinction may reflect the perceived limits of society to deal with catastrophic occurrences.
45 Fed. Reg. at 7141. In fact, the agency found, risks expected from highway transport of radioactive materials are minimal.
DOT took particular note of the possibility of a severe accident involving spent fuel or another type of large-quantity package. It found that "only large quantity packages pose even a remote risk of extraordinary or catastrophic accident consequences." Id. at 7148. It pointed out that such an accident was extremely unlikely, because the cask used for spent fuel shipments are massive (up to 35 tons) and able to sustain great impacts without rupture. Recognizing, however, that NUREG-0170 reported that a rupture could conceivably occur in extreme circumstances, the notice went on to describe the consequences of several "worst case" accidents. Some of these hypothetical accidents, DOT noted, could be extremely serious, but the most serious "is likely only once in 25 billion years and is thought by MTB not to warrant undue concern. A more typical high speed collision and fire in a highway accident is not likely to result in extensive radiological injuries or damage from the presence of either Type A, Type B or large quantity packages of radioactive materials." Id. at 7143.
The notice also recognized the possibility of sabotage. This risk, too, was limited to spent fuel and other large-quantity shipments. Although the possibility of such an attack exists, DOT suggested "the likelihood of a successful act of sabotage that breaches a spent fuel cask and disperses its contents may be quite small." Id. at 7150. Regulations established by the NRC for its licensees regarding shipments of spent fuel "will provide adequate physical protection" for licensees' shipments.
Finally, DOT maintained its resolve to refuse to consider alternative modes of transport. Despite the express suggestions of commentors that barging be considered where feasible, especially for spent fuel and other large-quantity shipments, the notice did not even mention barging. In a discussion of "Other Modes and Other Hazardous Materials," the agency only raised and deferred consideration of routing spent fuel by rail. Id. at 7l51-52. The Draft Environmental Assessment, moreover, considered only alternatives involving highways. The only option even arguably covering nonhighway transport -- to take no action -- gave no attention to barging as a potential means of eliminating the burden on commerce that some local rules might otherwise impose. The Assessment specifically found that taking no action would have few if any effects. Nevertheless, DOT rejected the no-action option and proposed to implement its previously suggested policy by making it absolutely clear that, irrespective of alternatives, any state or local rule preventing the use of highways for any type of shipment between any two points was inconsistent with DOT's proposed rule:
State and local requirements which apply to any person because that person transports radioactive material are inconsistent with this subchapter if they have any of the following effects.
(1) Completely prohibiting travel between any two points serviced by highway;
(2) Prohibiting the use of an Interstate highway, including prohibition of travel based on time of day, without designation of an equivalent preferred highway as a substitute in accordance with the provisions of this section . . . .
Id. at 7153 (proposed 49 C.F.R. § 177.825(d)).
The City responded to DOT's proposed rule on January 30, 1980. It took issue with DOT's analysis of dangers in transporting spent fuel and other large-quantity shipments through densely populated areas. In addition, the City renewed its criticism of DOT's refusal to consider the feasibility of transporting spent fuel by barge. It noted, in particular, that NUREG-0170, on which DOT placed great reliance for its findings and conclusions, had found barging a feasible alternative with respect to many reactor sites:
The fact that transportation costs are so much lower for barges than for other modes makes this alternative certainly worth additional investigation. Barge transportation of irradiated fuel may be a viable alternative, at least for some specific reactor sites, if not as a nationwide scheme.
NUREG-0170 at 6-11. The City contended, moreover, that barge transport was safer than highway transport of large-quantity shipments through its densely populated limits. Finally, arguing that its regulation afforded greater protection without burdening interstate commerce, the City requested that DOT issue a nonpreemption ruling with its final rule, so as to preclude the existence of a period in which spent fuel shipments by highway would be made through the City while its nonpreemption request was pending. Complaint of New York City, Ex. D.
DOT responded to the City's nonpreemption request on July 31, 1980. It included the City's comments in the record and agreed to consider them before taking final action. But it refused to docket the nonpreemption request, because no final rule had been promulgated with which the City's regulation could be deemed inconsistent. Douglas A. Crockett, then of DOT's Office of Chief Counsel, raised no other objection to the City's request at that time, and in fact suggested to then Corporation Counsel Allen G. Schwartz that "you may wish to renew your application at a more appropriate time." City Motion, Ex. M.
B. DOT's Final Rule, HM-164
DOT published its Final Rule on January 19, 1981, to take effect on February 1, 1982. 46 Fed. Reg. 5298 (1981). In most respects, the rule followed the scheme earlier proposed. In general, the rule divides covered shipments of radioactive materials into two groups. "Type A" shipments comprise "lower level" radioactive materials, such as isotopes used for medical, industrial, and research purposes. "Type B" shipments comprise "high level" or "large quantity" radioactive materials such as spent nuclear reactor fuel. 49 C.F.R. § 173.389 (1980). All other shipments are left essentially unregulated, as posing no hazard. The Final Rule establishes some guidelines for Type A shipments, requiring carriers of "placarded shipments" to use routes that "minimize radiological risk," but it does not mandate use of specified routes. For Type B shipments, by contrast, HM-164 requires the use of "preferred routes" for highway transportation. In particular, HM-164 provides, in relevant part:
Unless otherwise permitted by this section, a carrier and any person who operates a motor vehicle containing a package of large quantity radioactive material as defined in § 173.389(b) of this subchapter shall ensure that the vehicle operates over preferred routes selected to reduce time in transit, except that an Interstate System bypass or beltway around a city shall be used when available.
(1) A preferred route consists of -
(i) An Interstate System highway for which an alternative route is not designated by a State routing agency gas provided in this section, and
(ii) A State-designated route selected by a State routing agency (see § 171.8 of this subchapter) in accordance with the DOT "Guidelines for Selecting Preferred Highway Routes for Shipments of Large Quantity Radioactive Materials".
46 Fed. Reg. at 5316-17 (to be codified at 49 C.F.R. § 177.825(b)) (hereinafter cited only to C.F.R.). The "Guidelines" require that in selecting a preferred route, the state routing agency analyze radiation exposure, costs, economic risks from accidents, public health risks, emergency response capabilities, evacuation plans, traffic fatalities and injuries, and the locale of special facilities. City Motion, Ex. W.
The Final Rule deleted from the official regulations the provision expressly declaring inconsistent all local bans on highway transport. Instead, DOT reiterated that position and policy at greater length in what was to become Appendix A to C.F.R. Part 177. 46 Fed. Reg. at 5317. State and local jurisdictions are informed how they "can exercise authority over motor carriers under [their] own laws in a manner that the Department of Transportation considers to be consistent with rules in Part 177." The Appendix states, in relevant part:
III. Large quantity radioactive materials
A. State routing rules. A State routing rule which applies to large quantity radioactive materials is inconsistent with Part 177 if --
1. It prohibits transportation of large quantity radioactive materials by highway between any two points without providing an alternate route for the duration of the prohibition; or
2. It does not meet all of the following criteria:
(a) The rule is established by a State routing agency as defined in § 171.8 of this subchapter;
(b) The rule is based on a comparative radiological risk assessment process at least as sensitive as that outlined in the "DOT Guidelines";
(c) The rule is based on evaluation of radiological risk wherever it may occur, and on a solicitation and substantive consideration of views from each affected jurisdiction, including local jurisdictions and other States; and
(d) The rule ensures reasonable continuity of routes between jurisdictions.
B. Local routing rules. A local routing rule that applies to large quantity radioactive materials is inconsistent with this Part if it prohibits or otherwise affects transportation on routes or at locations either -
1. Authorized by Part 177, or
2. Authorized by a State routing agency in a manner consistent with Part 177.
Under this interpretive policy, § 175.111(1) of the New York City Health Code is inconsistent with the routing rules of 49 C.F.R. § 177.825(b) because it effectively prohibits use of the highways for shipments through New York City of large-quantity radioactive materials.
DOT persisted, in adopting the Final Rule, in refusing to evaluate alternative modes of transport. It resolved to consider "only routing requirements for radioactive materials shipped by highway, the focus of most State and local actions, rather than undertake & comprehensive regulatory proceeding to consider all classes of hazardous materials and all modes of transportation." 46 Fed. Reg. 5300 (1981). The Regulatory Evaluation and Environmental Assessment filed with the Final Rule also reflected this policy. It restricted its consideration of alternatives to taking no action (which it found would have little or no effect), and to taking a variety of other actions, all involving highways. Environmental Assessment, DOT Motion, Ex. D.
The ultimate basis for DOT's Final Rule is "that the public risks in transporting these materials by highway are too low to justify the unilateral imposition by local governments of bans and other severe restrictions on the highway mode of transportation." 46 Fed. Reg. at 5299. This same finding supports DOT's policy decision in Appendix A to deem inconsistent with the Final Rule any nonfederal rule preventing highway transport:
A State cannot make transportation between two points impossible by highway. The radiological risks in transporting large quantity radioactive materials by highway are small and total preclusion of shipments cannot be justified on that basis.
Id. at 5313; see id. at 5317 (49 C.F.R. Part 177, app. A, pt. III (1)). See also id. at 5309: "[P]ackages of large quantity radioactive materials can be transported over any Interstate highway, and most other comparable [highway] routes, with a confident level of safety."
In reaching this conclusion, DOT was aware of the potential for a serious accident in a densely populated area. It stated at one point that the "accident rate is not the only important element to consider in assessing risk to the public -- one must consider the consequences of a serious accident, even though the probability of that accident may be small." Id. at 5301. It affirmed at another point that DOT, "also, is concerned with such events [as high consequence accidents] and is mindful of the large economic consequences estimated for such hypothetical events by [tile recent SANDIA report]. These estimates relate to a scenario which assumes the worst credible accident for certain truck shipments of spent fuel and polonium in densely populated urban areas." Id. at 5299. Nevertheless, DOT concluded, the potential consequences of such accidents did not warrant allowing a state or locality to prevent highway transport, at bottom because the consequences were highly unlikely, and "these currently low risks will be further minimized by the adoption of driver training requirements and provisions of a method for selecting the safest available highway routes for carriers of large quantity radioactive materials, as accomplished in this rule." Id.3
DOT stated its position with respect to low-probability/high-consequence accidents in very general terms. "Many commenters," the agency contended, "seem to be concerned only with consequence particularly high consequence accidents involving large quantity radioactive materials in a heavily populated urban center." Id. A proper assessment of the risk of such accidents, DOT said, must be more balanced:
[A]n assessment of risk to the public from accidents involving large quantity radioactive materials should include a balanced consideration of factors which affect both the likelihood of an accident as well as the consequences.
Id. High-consequence accidents should be "of great concern," said DOT, "but not to the extent that public policy on hazardous material routing should be formulated solely on the basis of avoiding such 'worst case' accidents." Id. at 5315. See also id. at 5300. The probability of such accidents was low enough, in DOT's view, for the overall risk to be deemed acceptable.
If, in addition to low risk, "other factors" were considered by DOT in reaching its conclusion, they were not described as such. Two factors, however, seem to have been considered. First, DOT concluded that public concern over the worst-case accident is irrational, because the same public is willing to bear much greater risks, including the consequences of ordinary highway accidents. See p. 10 supra. Second, DOT regarded local laws in particular as highly suspect and likely to reflect public irrationality. Indeed, the Final Rule and its accompanying documents are a veritable essay in political philosophy, expressing DOT's skepticism of the capacity of localities to adopt rules worthy of national, or even regional, respect. The rulemaking, DOT noted, was necessary to "consider the overall safety impact of piecemeal, uncoordinated local actions on hazardous material transportation," actions DOT characterized as "narrowly conceived."
46 Fed. Reg. at 5300. Although it noted the argument of "commenters" that, in the United States, local governments have traditionally had primary responsibility for highway safety and for public health, as well as the duty to respond to and clean up after serious accidents, DOT explained:
Local jurisdictions are inherently limited in perspective with respect to establishing routing requirements. While the Department recognizes that local governments are accountable only to their own citizens, such a limited accountability has some undersirable effects.
While repeatedly expressing its resolved not to examine alternative modes of transport in its rulemaking, DOT nevertheless twice expressed the view that alternative modes would not clearly reduce public risks. Thus, early in its discussion of the Final Rule, DOT stated without elaboration or support:
Other modes of transport generally do not appear to offer alternatives which clearly lower public risks to the extent that use of the highway mode should be substantially restricted.
Id. at 5299. DOT's second comment on the subject, and its most comprehensive statement of its understanding of its HMTA responsibilities, is found in the Supplement to Docket HM-164: Summary and Analysis of Public Comments, DOT Motion, Ex. E. In responding to criticism of its decision to refuse to consider alternative modes of transport that might avoid a possible catastrophe, DOT stated that it willingly assumed responsibility for imposing the risk, because the risk was small and could not significantly reduced by resorting to be other modes:
A number of commenters do not share MTB's opinion that this rulemaking be so severely limited. Although none of the proposed or adopted rules pertain to other modes or other hazardous materials the Bureau believes that a discussion of these comments is appropriate.
The most prominent comments addressing this area question MTB's failure to impose a requirement on shippers of large quantity radioactive materials packages to evaluate the risks identified with each mode or combination of modes and then select the method which is most favorable on the basis of the expected impacts on public health and safety. These commenters go on to say that the potential for catastrophe does exist whenever large quantities of radioactive materials are transported in urbanized areas and that it is a proper function of government to safeguard its citizens from such a possible tragedy. In essence MTB finds itself in general agreement with these comments and must conclude that the differences which exist are not of a philosophical nature but rather are represented by varying degrees of protection which reasonable minds may find difficult in reaching a consensus. [sic ] When differences such as these cannot otherwise be resolved a judgement must be made by the responsible party. In this case the MTB has primacy over hazardous materials transportation and believes that this exercising of its authority is in order. The determination made by MTB applicable to large quantity radioactive materials packages transported by public highway is that they can be shipped with confidence of an acceptable level of safety and therefore such packages should not be subjected to compulsory modal shifts which result in the fractional reduction of an other wise low risk. This policy is consistent with MTB's history of recognizing the inherent risks appropriate to the transportation of particular hazardous materials by each of the modes, and its reluctance to specify an order of precedence in the choices available to shippers regarding the physical state of their materials, packagings, quantity amounts, and the like. Such a policy would also not appear to violate recommendations made by the National Council on Radiation Protection (NCRP) concerning the maintenance of dose rates at levels which are "as low as reasonably achievable."
DOT Motion Ex. E, pt. H.2. The same assumptions that led DOT to discount the potential consequences of serious accidents led it to reaffirm its view that the possibility of sabotage did not warrant allowing states or localities to prohibit some shipments through or near densely populated areas. DOT Motion, Ex. E, pt. E at 6.
C. The City's Nonpreemption Request
The City responded by letter to DOT's Final Rule on March 20, 1981, criticizing the rule's premises at length, and renewing the City's request for a nonpreemption ruling. City Motion, Ex N. The City noted that DOT's express declaration in Appendix A rendered the City's regulation inconsistent, but the City insisted that its local ...