198 F.3d 944 (D.C. Cir. 1999)
Association of American Railroads, Petitionerv.Department of Transportation, et al., Respondents,Brotherhood of Maintenance of Way Employees, Intervenor
No. 99-1116
United States Court of AppealsFOR THE DISTRICT OF COLUMBIA CIRCUIT
Argued October 12, 1999Decided December 28, 1999

On Petition for Review of an Order of the United States Department of Transportation
Ian Heath Gershengorn argued the cause for petitioner.  With him on the briefs were John Broadley, Louis P. Warchot, and Michael J. Rush.
Dale C. Andrews, Deputy Assistant General Counsel, U.S.  Department of Transportation, argued the cause for respondents. With him on the brief were Nancy E. McFadden,  General Counsel, and Paul M. Geier, Assistant General Counsel.
Richard S. Edelman was on the brief for intervenor.
Before:  Ginsburg, Rogers and Tatel, Circuit Judges.
Opinion for the Court filed by Circuit Judge Tatel.
Tatel, Circuit Judge:


1
Acting without notice and comment,  the Federal Railroad Administration issued a technical bulletin interpreting a safety regulation the agency had issued  through formal rulemaking just two years earlier.  Petitioner  claims that the technical bulletin abruptly departed from the  agency's previous interpretation of the regulation and that it  therefore required notice and comment rulemaking.  We  disagree.  Reviewing the random and conflicting agency letters and other documents relied on by petitioner, we find no  evidence of a definitive agency interpretation that could be  changed only through notice and comment.  We therefore  deny the petition for review.


2
* Congress directed the Secretary of Transportation to "prescribe regulations and issue orders for every area of railroad  safety...."  49 U.S.C.  20103(a).  To "carry out all railroad  safety laws of the United States," Congress created the  Federal Railroad Administration, also a respondent in this  case.  49 U.S.C.  103(a);  see also 49 C.F.R.  1.49 (delegating authority from the Secretary of Transportation to the  Federal Railroad Administrator).


3
The Rail Safety Enforcement and Review Act of 1992  directs the Secretary to review and revise federal rules  relating to railroad track safety.  See Rail Safety Enforcement and Review Act  8, 49 U.S.C.  20142.  Responding  to that directive, the FRA conducted a study and found  that from 1989 to 1993 twenty-two roadway workers were  struck and killed by trains or on-track equipment.  Based  on these findings and the results of a similar study by a  joint labor-management task force, the FRA established a federal advisory committee comprised of representatives  from management, labor, and the agency to engage in a  negotiated rulemaking on the subject of roadway worker  safety.  The advisory committee eventually produced the  Roadway Worker Protection Rule, which, following notice  and comment, became effective in January 1997.  See 49  C.F.R. §§ 214.301-214.355.


4
The Roadway Worker Protection Rule establishes procedures to protect roadway workers from accidents involving  trains or other on-track equipment.  At issue in this case is  the Rule's procedure for demarcating portions of track where  railroad employees are working and on-track accidents generally occur.  The Rule refers to these areas as "working  limits."


5
The precise method of establishing working limits depends  on whether the work is being performed on track that is  "controlled" or "non-controlled."  On non-controlled track,  i.e., track on which trains may move without authorization  from a dispatcher or control operator, the only acceptable  method of establishing working limits is to render the area  "physically inaccessible to trains at each possible point of  entry."  49 C.F.R.  214.327(a).  On controlled track, i.e.,  track on which all train movements must be expressly authorized, the Roadway Worker Protection Rule allows the track  to remain accessible but requires that the boundaries of  working limits be marked by certain procedures, one of which  is known as "exclusive track occupancy."  See 49 C.F.R.   214.321.  Exclusive track occupancy requires railroads to  mark the boundaries of working limits with a flagman, a fixed  signal displaying "Stop," a station identified in the railroad's  timetable, a clearly identifiable milepost, or, in language  central to this case, any other "clearly identifiable physical  location prescribed by the operating rules of the railroad that  trains may not pass without proper authority."  See 49 C.F.R.  214.321(c)(1)-(5).  We will refer to this last option as "paragraph (c)(5)."


6
Railroads taking advantage of the paragraph (c)(5) option  often use unattended red flags to mark the boundaries of working limits.  When a train enters a segment of controlled  track containing working limits, a dispatcher directs the train  engineer to travel at restricted speed until the train arrives at  the unattended red flag, at which point it stops and awaits  instructions from the roadway worker in charge of the working limits.  The Rule provides that the roadway worker in  charge may not allow trains to pass the red flag and enter the  working limits until certain specified steps are taken to  protect the safety of roadway workers.  See 49 C.F.R.   214.319(c).


7
The dispute in this case centers on the precise amount of  information about the red flag that paragraph (c)(5) requires  the dispatcher to give the train engineer.  Petitioner, the  Association of American Railroads (AAR), argues that paragraph (c)(5) requires the dispatcher to tell approaching trains  nothing more than that they will encounter a red flag somewhere within the segment of controlled track.  The FRA,  supported by intervenor, the Brotherhood of Maintenance of  Way Employees, reads the regulation to mean that the train  engineer must be told not just that a red flag exists somewhere within the segment of controlled track, but of the flag's  precise location.  Without such notice, the FRA maintains,  worker safety would depend entirely on trains traveling at  restricted speed, the pre-Rule precaution that the agency  found insufficient to protect roadway workers.  See, e.g.,  Roadway Worker Protection, 61 Fed. Reg. 10528, 10536 (proposed Mar. 14, 1996) ("[A] blanket provision that would rely  upon restricted speed to protect persons working [on] the  track would not be effective.").  According to the AAR,  however, it is not always possible to keep a dispatcher  informed of the precise location of working limits, particularly  since roadway workers often move down the track, or "float,"  as work progresses.  Notification thus requires constant radio communication, but "in the western United States ...  topographical and other constraints make radio communication difficult over extended portions of the track."


8
Two years after issuing the Roadway Worker Protection  Rule, the FRA incorporated its view of paragraph (c)(5) in  Workplace Safety Technical Bulletin WPS-99-01 (January 1999).  Issued without notice and comment, the technical  bulletin directs that when unattended red flags or other  passive devices are used to demarcate working limits, trains  "must be provided with advance notification of the type and  exact location of these devices."


9
In this petition for review, the AAR does not challenge the  advance notice requirement as an unreasonable interpretation  of the Roadway Worker Protection Rule.  Rather, claiming  that the FRA had previously interpreted paragraph (c)(5) as  not requiring advance notice of precise flag location and that  the bulletin amounts to an "abrupt departure" from that  interpretation, the AAR argues that the Administrative Procedure Act required the agency to issue the bulletin through  notice and comment rulemaking.  For its part, the FRA  maintains that it never ruled that paragraph (c)(5) did not  require advance notice of precise flag location, that agency  officials have consistently told railroads that unattended red  flags and restricted speed alone do not comply with the  Roadway Worker Protection Rule, and that notice and comment were not required because the technical bulletin is  consistent with that position.

II

10
Section 553 of the Administrative Procedure Act requires  "[g]eneral notice of proposed rule making," 5 U.S.C.  553(b),  and that "interested persons [have] an opportunity to participate in the rule making through submission of written data,  views, or arguments."  5 U.S.C.  553(c).  "Interpretative  rules" are specifically exempted from the Act's notice and  comment requirements.  5 U.S.C. §§ 553(b)(A), (d)(2);  see  also Interport Inc. v. Magaw, 135 F.3d 826, 828 (D.C. Cir.  1998).  Interpretative rules "simply state[ ] what the administrative agency thinks the statute means, and only remind[ ]  affected parties of existing duties."  General Motors Corp. v.  Ruckelshaus, 742 F.2d 1561, 1565 (D.C. Cir. 1984) (en banc)  (internal quotation marks omitted).  Interpretative rules may also construe substantive regulations.  See Syncor Internat'l  Corp. v. Shalala, 127 F.3d 90, 94 (D.C. Cir. 1997).


11
The AAR contends that the technical bulletin cannot be an  interpretative rule because it "effects a change in existing law  or policy."  In support, the AAR relies on our recent decision  in Alaska Professional Hunters Ass'n, Inc. v. FAA, 177 F.3d  1030 (D.C. Cir. 1999).  There, Alaskan fishing and hunting  guides challenged a Federal Aviation Administration notice  that required guides to comply with FAA regulations applicable to commercial air operations.  The notice abruptly reversed a previously settled practice of the FAA, which  through its Alaskan Region had for decades advised guides  that they need not comply with commercial pilot regulations.We agreed with the guides that the notice should have been  issued through notice and comment rulemaking.  "[A]ll  agree[d] that FAA personnel in Alaska consistently followed  the interpretation in official advice to guides and guide services" for approximately thirty years.  Id. at 1032.  Originating in a 1963 adjudication, that advice was longstanding,  uniform, and unambiguous.  See id. at 1031. "When an  agency has given its regulation a definitive interpretation, and  later significantly revises that interpretation," we explained,  "the agency has in effect amended its rule, something it may  not accomplish without notice and comment."  Id. at 1034;see also Syncor Internat'l, 127 F.3d at 94 (stating that a  modification of an interpretative rule construing an agency's  substantive regulation "will likely require a notice and comment procedure").


12
The AAR claims that this case is like Alaska Professional  Hunters.  Just as the FAA had definitively ruled that Alaskan guides were not subject to commercial air regulations,  here the AAR argues that the FRA had determined that  prior notice of a red flag's precise location was unnecessary.The AAR detects this definitive interpretation in the Roadway Worker Protection Rule's Preamble, in an email and two  letters from agency personnel, and in the agency's own safety  manual.  We find nothing in these materials, individually or  taken together, that comes even close to the definitive interpretation that triggered notice and comment rulemaking in  Alaska Professional Hunters.


13
To begin with, two of the documents relied on by the AAR  provide no support at all for its position.  The Rule's Preamble states that "working limits are delineated by flags as  specified in [paragraph] (c)(5)."  61 Fed. Reg. 65959, 65969.As the agency points out, this language says no more than  that working limits may be marked by flags.  It says nothing  about whether notice of the flag's precise location is required.The email message, written by an FRA bridge engineer,  Gordon Davids, suggests that paragraph (c)(5) could be satisfied by "operating through the zone in which the red flag may  be encountered at restricted speed, looking out for the red  flag."  Not only does Davids have no policy-making authority,  however, but his phrase "looking out for the red flag," like the  Preamble language, says nothing about whether the engineer  must be given notice of the flag's precise location.


14
Other evidence the AAR cites is somewhat more convincing.  A letter to a railroad official from George Gavalla, then  Acting (now permanent) FRA Associate Administrator for  Safety, and previously a labor representative on the federal  advisory committee, states the following:


15
The principle behind the use of flags to establish workinglimits on controlled track.... calls for all trains ... to beaware of the existence of flags or other appropriatesignals delineating the working limits.  They might notknow the exact location of those flags because the flagsmight be moved as the work progresses, but they mustknow that somewhere within a defined track segmentthey will encounter the flags.  That principle has beenfaithfully captured in the text of the regulation.


16
(Emphasis in original.)  Another letter to the same railroad  official from Gavalla's subordinate, Edward English, contains  similar language:  "The use of red flags to establish working  limits ... is permissible because even though the flags may  'float' as the work progresses, trains ... know that somewhere within a defined track segment they will encounter the  red flags."  The FRA's Railroad Workplace Safety manual  states:


17
[A] train must be informed of the existence of workinglimits....  It is not sufficient to just place flags and goto work.  However, a railroad may permit the flags to bemoved as the work progresses, so long as all trainsapproaching the working limits are informed of theirexistence.


18
Not surprisingly, the FRA interprets these items rather  differently.  The Gavalla letter, the FRA tells us, mainly  concerns safety requirements for non-controlled track.  Conceding that the quoted language appears in a paragraph  relating to controlled track, the agency insists that Gavalla's  comment was made "in passing and to illustrate a point, [and]  he was notinterpreting, nor was he asked to interpret, the  requirements of section [2]14.321, which address controlled  track."  At oral argument, the agency took a different tack,  arguing that when the Gavalla and English letters said that  train engineers must know that "somewhere within a defined  track segment" they will encounter red flags, they were  referring to an extremely short "defined track segment,"  apparently meaning that advance notice that flags are within  that segment would amount to notice of the flags' location.As for the safety manual, the FRA points out that the manual  never expressly states that red flags and restricted speed  alone are sufficient to comply with the Roadway Worker  Protection Rule.  At oral argument, agency counsel added  that the manual's phrase "informed of [the flags'] existence"  should be read to imply "informed of their location."


19
The FRA offers its own evidence to demonstrate that it has  consistently advised the railroads that red flags and restricted speed alone are insufficient to comply with the Roadway  Worker Protection Rule.  It refers to a February 13, 1998,  letter from the AAR complaining that members of the FRA  staff appear unwilling to accept the use of red flags as a  satisfactory means of marking working limits.  The FRA also  points out that several reports finding that certain railroads  violated the Roadway Worker Protection Rule noted that red  flags were the only form of protection the railroads had used.  In addition, the FRA asserts that the General Code of  Operating Rules--a set of model procedures to which railroads that use paragraph (c)(5) subscribe--requires certain  practices that would have the effect of providing trains with  advance notice of working limits.  This is significant, the  agency tells us, because paragraph (c)(5) expressly incorporates "the operating rules of the railroad."  49 C.F.R.   214.321(c)(5).


20
We are not at all sure what the various and sundry bits of  evidence marshaled by the parties tell us about the meaning  of paragraph (c)(5).  To be sure, some of the evidence,  particularly the Gavalla letter, seems to support the AAR's  position, and we find ourselves unconvinced by the agency's  efforts to explain the letter away as, among other things, the  railway equivalent of judicial dictum.  We are equally underwhelmed by the agency's own evidence.  Although the violation reports do note that red flags were the only form of  protection used in some cases, not one of the reports states  that the Rule requires advance notice of the red flag's location.  The AAR's February 13 letter does indicate, as the  agency points out in its brief, that the "AAR expressed its  awareness of, and opposition to, how [the] FRA was interpreting its rule on these issues."  But at oral argument, the  AAR explained that it wrote the letter precisely because it  believed that agency officials were departing from their prior  interpretation of the Roadway Worker Protection Rule.


21
Even interpreting the evidence in the light most favorable  to the AAR, however, we think it is quite clear that the FRA  never adopted a definitive interpretation of paragraph (c)(5)  that it could change only through notice and comment rulemaking.  Although the AAR has unearthed some documents  that seem, albeit sometimes vaguely, to support its argument  that the agency--or at least some of its employees--may  have interpreted paragraph (c)(5) as not requiring notice of  precise flag location, none of those documents even comes  close to the express, direct, and uniform interpretation present in Alaska Professional Hunters.  Also, unlike Alaska  Professional Hunters, where the regional office's position was reflected in official agency adjudications holding that Alaskan  guides need not comply with commercial pilot standards, see  177 F.3d at 1031, 1032, nothing in this record indicates that  the FRA ever held that the Roadway Worker Protection Rule  did not require advance notice of red flag location.  Indeed,  as far as we can tell, prior to the technical bulletin, the issue  regarding notice of flag location had been the subject of no  official agency proceeding.  In other words, this record reveals no "administrative common law" (this court's words in  Alaska Professional Hunters, 177 F.3d at 1035) that paragraph (c)(5) does not require notice of precise flag location.


22
This case differs from Alaska Professional Hunters in  another important respect.  Believing that they were exempt  from commercial pilot regulations, "Alaskan guide pilots and  lodge operators relied on the advice FAA officials imparted to  them--they opened lodges and built up businesses dependent  on aircraft."  Id. at 1035.  Nothing in this record suggests  that railroads relied on the Gavalla letter or other documents  in any comparable way.  The AAR does not claim that its  members made large capital expenditures based on their  interpretation of paragraph (c)(5) or altered their business  practices in any significant manner.  Instead, the AAR claims  that the railroads' agreement with the outcome of the negotiated rulemaking was "critically dependent on their ability  (consistent with the regulations) to use red flags [alone] to  demarcate working limits."  Yet the AAR points to no evidence to support this assertion;  all evidence in the record is  post-negotiated rulemaking.  Even if true, moreover, agreement to a negotiated rulemaking based on a presumptive  interpretation of ambiguous language hardly compares to the  three decades of business development that had occurred in  Alaska Professional Hunters.


23
To sum up, we see the record in this case quite differently  than does the AAR.  We read the various letters and other  documents relied on by the AAR not as evidence of a firm  agency policy, but rather as the agency's initial efforts to  respond to the dispute over the meaning of paragraph (c)(5) that flared up shortly after the Roadway Worker Protection  Rule was issued.  As one would expect when agency personnel face controversies of this kind, their responses were often  ambiguous and incomplete.  Not until the agency issued the  technical bulletin was the controversy officially and definitively resolved.  If, as the AAR urges, the record in this case  reflects a definitive interpretation of paragraph (c)(5), it  would mean that an agency's initial, often chaotic process of  considering an unresolved issue could prematurely freeze its  thinking into a position that it would then be unable to change  without formal rulemaking.  Not only would this blur the  distinction between definitive agency action and informal,  uncoordinated communications, it would seriously hamstring  agency efforts to interpret and apply their own policies.  The  Administrative Procedure Act requires no such result.

III

24
In the final section of its brief, the AAR argues that the  technical bulletin is "substantively invalid ... because the  FRA's abrupt departure from its contemporaneous and consistent construction of the exclusive track occupancy provision  is arbitrary and capricious."  Except for the label "substantive," we see no difference between this claim and the procedural argument that we rejected in section II.  The petition  for review is denied.


25
So ordered.

