delivered the opinion of the court:
The plaintiff, Tracy Templeton, was an employee of the defendant railroad, Chicago and Northwestern Transportation Company. On January 27, 1984, plaintiff was performing track work on a bridge located in Pekin, Illinois. Plaintiff fell through an opening in the bridge deck and landed on ice 31 feet below the bridge. Plaintiff filed suit in the circuit court of Cook County under the Federal Employers’ Liability Act (45 U.S.C. §51 (1988)), to recover damages for the injuries he sustained as a result of the fall. A jury awarded plaintiff damages in the amount of $3.5 million after a reduction of 14% for plaintiff’s contributory negligence.
Defendant appealed contending, inter alia, that the trial court improperly admitted into evidence “fall-protection” regulations issued by the Federal Occupational Safety and Health Administration (OSHA) and instructed the jury on the same. The appellate court reversed (211 Ill. App. 3d 489), and we granted plaintiff’s petition for leave to appeal (134 Ill. 2d R. 315).
At issue in this case is whether OSHA’s fall-protection regulations applied to the railroad bridge upon which plaintiff was working at the time of the accident. Defendant argues that OSHA’s regulations did not apply because the Federal Railroad Administration (Railroad Administration) had asserted its exclusive authority over railroad bridges and, thereby, displaced OSHA’s jurisdiction over the bridge. Defendant relies on a Railroad Administration policy statement issued in 1978 as support for this argument.
The Occupational Safety and Health Act of 1970 (29 U.S.C. §651 et seq. (1988)) was enacted to address the problems caused by personal injuries and illnesses arising out of working conditions. As part of the solution to this problem, Congress authorized the Secretary of Labor to “set mandatory occupational safety and health standards applicable to businesses affecting interstate commerce.” (29 U.S.C. §651(b)(3) (1988).) Pursuant to the Occupational Safety and Health Act, OSHA has general authority to promulgate health and safety regulations relative to hazards arising out of working conditions.
At trial, plaintiff introduced into evidence two OSHA fall-protection regulations which are contained in OSHA’s construction industry regulations. (See 29 C.F.R. §§1926.104, 1926.105 (1991).) One of the regulations entered into evidence provides in pertinent part:
“Safety nets shall be provided when workplaces are more than 25 feet above the ground or water surface, or other surfaces where the use of ladders, scaffolds, catch platforms, temporary floors, safety lines, or safety belts is impractical.” 29 C.F.R. §1926.105(a) (1991).
Because this regulation was incorporated into the general industry standards applicable to all industries (29 C.F.R. §1910.12 (1991)), plaintiff claims it applies to work on railroad bridges.
Defendant argues that OSHA’s fall-protection regulations do not apply to this case because the Railroad Administration has specifically preempted OSHA from regulating work on railroad bridges. Section 4(b)(1) of the Occupational Safety and Health Act provides in pertinent part:
“Nothing in this chapter shall apply to working conditions of employees with respect to which other Federal agencies *** exercise statutory authority to prescribe or enforce standards or regulations affecting occupational safety or health.” (29 U.S.C. §653(b)(1) (1988).)
In order for another Federal agency, in this case the Railroad Administration, to preempt OSHA regulations under section 4(b)(1), that agency must have statutory authority to regulate a specific industry and it must exercise that authority over a particular working condition. Southern Pacific Transportation Co. v. Usery (5th Cir. 1976), 539 F.2d 386.
Under the Federal Railroad Safety Act of 1970 (45 U.S.C. §421 et seq. (1988)), the Railroad Administration is the primary agency responsible for regulating the railroad industry and has the statutory authority to issue safety regulations for railroads which would displace OSHA regulations. In 1978, the Railroad Administration issued a policy statement which outlined its position on those areas of the railroad industry for which the Railroad Administration was preempting OSHA regulations. (43 Fed. Reg. 10583 (1978).) Although the policy statement did not promulgate any new safety regulations, it was sufficient to preempt OSHA from exercising jurisdiction over some aspects of the railroad industry. See Velasquez v. Southern Pacific Transportation Co. (5th Cir. 1984), 734 F.2d 216; Secretary of Labor v. Consolidated Rail Corp. (1982), 10 O.S.H. Cas. (BNA) 1577.
However, it is clear from the policy statement that the Railroad Administration did not intend to completely displace OSHA regulations. The policy statement envisions an evolving, cooperative relationship between the two Federal agencies. For example, in the policy statement the Railroad Administration stated the following:
“[The Railroad Administration] recognizes that OSHA currently is not precluded from exercising jurisdiction with respect to conditions not rooted in railroad operations nor so closely related to railroad operations as to require regulation by [the Railroad Administration] in the interest of controlling predominant operational hazards.
* * *
*** We believe the policy set forth in this document will assure that each of the principal Federal agencies charged with the responsibility for carrying out this program, that is, [the Railroad Administration] and OSHA, will concentrate its efforts in those areas in which it possesses the greatest experience and expertise. In those cases in which there may be some question as to which is the primary regulatory agency, cooperative efforts between the two agencies should avoid the creation of regulatory gaps on the one hand, or unnecessary duplication on the other. At any time that a hazardous working condition impacts upon the overall safety of railroad operations, [the Railroad Administration] will take the initiative in developing a proper regulatory response.” (Emphasis added.) 43 Fed. Reg. 10587-90 (1978).
In the policy statement, the Railroad Administration specifically addressed the applicability of 13 separate categories of OSHA regulations. Defendant cites the following passage from the Railroad Administration’s discussion of OSHA’s “walking-working surfaces’’ regulations as proof that the Railroad Administration intended to displace OSHA from regulation of all working conditions on railroad bridges:
“OSHA regulations concerning working surfaces deal with such matters as ladders, stairways, platforms, scaffolds and floor openings. Generally, these regulations are applicable in railroad offices, shops and other fixed work places. There are three principal exceptions to the rule.
•k «k si*
***
Third, the OSHA regulations would not apply to ladders, platforms, and other surfaces on signal masts, cantenary systems, railroad bridges, turntables, and similar structures or to walkways beside the tracks in yards or along the right-of-way. These are areas which are so much a part of the operating environment that they must be regulated by the agency with primary responsibility for railroad safety.” (43 Fed. Reg. 10587 (1978).)
The OSHA regulations referred to in the above passage require the use of railings, toeboards and hole covers to be placed over or around an opening in a floor or wall surface. (See 29 C.F.R. §1910.23 (1991).) Based on the policy statement, these OSHA regulations are not applicable to railroad bridges. Velasquez, 734 F.2d at 218.
However, as noted above, the fall-protection regulations at issue in this case are included in OSHA’s construction industry regulations. The Railroad Administration addressed separately the applicability of OSHA construction regulations. It is unclear from this section of the policy statement whether the Railroad Administration intended to displace OSHA fall-protection regulations. Specifically, the Railroad Administration stated:
“To the extent that hazardous construction working conditions do not fall within [the Railroad Administration’s] exercise of authority relating to the safety of railroad operations, the OSHA standards apply according to their terms in the railroad industry.” (43 Fed. Reg. 10589 (1978).)
This section is ambiguous in that it is not clear which “hazardous construction working conditions” are within the Railroad Administration’s exercise of exclusive authority.
When construing an administrative regulation, “ ‘a court must necessarily look to the administrative construction of the regulation if the meaning of the words used is in doubt. *** [T]he ultimate criterion is the administrative interpretation, which becomes of controlling weight unless it is plainly erroneous or inconsistent with the regulation.’ ” Udall v. Tallman (1965), 380 U.S. 1, 16-17, 13 L. Ed. 2d 616, 625, 85 S. Ct. 792, 801, quoting Bowles v. Seminole Rock & Sand Co. (1945), 325 U.S. 410, 413-14, 89 L. Ed. 1700, 1702, 65 S. Ct. 1215, 1217.) With this principle in mind, it is significant to note that the Railroad Administration does not interpret its policy statement as preempting OSHA from enforcing the fall-protection regulations on railroad bridges.
In 1991, the Railroad Administration issued a notice of proposed rulemaking in which the agency announced its intent to promulgate fall-protection regulations substantially similar to the OSHA regulations at issue here. (See 56 Fed. Reg. 3434 (proposed Jan. 30, 1991).) In the jurisdictional background section of the 1991 notice, the Railroad Administration quoted the “walking-working surface” section of the policy statement and stated:
“[The Railroad Administration] intended to displace OSHA regulations with respect to the surfaces on bridges, i.e., track structures, but did not intend to prevent OSHA from exercising its more general responsibilities for the safety of railroad workers with respect to fall protection and respiratory equipment.” (Emphasis added.) (56 Fed. Reg. 3435 (proposed Jan. 30,1991).)
This interpretation of the policy statement indicates that the Railroad Administration itself believes OSHA had jurisdiction over the working condition at issue in this case. Because we are construing a Railroad Administration regulation, this interpretation is controlling “ ‘unless it is plainly erroneous or inconsistent with the regulation.’ ” Udall, 380 U.S. at 18-17, 13 L. Ed. 2d at 625, 85 S. Ct. at 801, quoting Bowles, 325 U.S. at 414, 89 L. Ed. at 1702, 65 S. Ct. at 1217.
Defendant contends that the above-quoted Railroad Administration interpretation of the policy statement is not controlling because it is inconsistent with the clear language of the 1978 policy statement. Defendant argues that the Railroad Administration’s 1991 interpretation provides nothing more than an attempt to retroactively revise the Railroad Administration’s prior statement. It is clear, as defendant points out, that the 1978 policy statement intended to displace OSHA regulations from “railroad operations.” What is unclear, however, is whether the use of safety nets and other fall-protection devices on railroad bridges impacts upon “railroad operations.” We note that the policy statement is sufficiently ambiguous to support either interpretation. Indeed, the Railroad Administration recognized such ambiguity when it stated:
“[T]o the extent matters addressed by the OSHA regulations are connected with or relate to railroad operations and may interact with or create operational hazards, it may be necessary for [the Railroad Administration] and OSHA to consult concerning the interpretation or modification of such standards. As the primary regulatory agency concerned with railroad safety, [the Railroad Administration] will not hesitate to adopt its own standards to assure a safe environment for railroad operations and to promote regulatory consistency.” (43 Fed. Reg. 10587 (1978).)
Moreover, the policy statement was a statement of general principle, rather than a definitive declaration. 43 Fed. Reg. 10587 (1978).
The Railroad Administration addressed this ambiguity again in the 1991 notice of proposed rulemaking when it stated:
“[T]hese distinctions [between bridge surfaces and fall protection] have proved confusing to the regulated community, railroad employees, inspectors, and *** adjudicatory bodies. [The Railroad Administration] has recently received a number of legal memoranda addressing these issues from railroads and railroad associations: all of these evidence this confusion.” (56 Fed. Reg. 3435 (proposed Jan. 30,1991).)
In fact, defendant is one of the railroads referred to by the Railroad Administration as having submitted legal memoranda. 56 Fed. Reg. 3436 (proposed Jan. 30, 1991).
Based on the above excerpts from both the 1978 and the 1991 Railroad Administration pronouncements, we are unable to conclude that the Railroad Administration has unambiguously preempted OSHA from regulating the use of fall-protection equipment on railroad bridges. As the policy statement is subject to two competing interpretations which are equally reasonable, we believe the most appropriate interpretation is that which the Railroad Administration itself has adopted. Therefore, we hold that the OSHA fall-protection regulations applied to the present case.
We note that the Velasquez decision on which defendant and the appellate court relied is distinguishable. In Velasquez, the plaintiff fell through an opening in the track on a railroad bridge and landed on a creek bed nine feet below. The plaintiff in that case introduced evidence that “under OSHA regulations, rope barricades and a toeboard around the perimeter of the opening would have been appropriate measures.” (Velasquez, 734 F.2d at 218.) From these facts it is clear that the plaintiff in Velasquez attempted to introduce evidence of OSHA ‘‘walking-working surface” regulations. The OSHA safety-net regulations did not apply because the plaintiff in Velasquez was substantially below the 25-foot threshold level at which a safety net is required.
In dicta, the Velasquez court noted that OSHA’s construction regulations did not apply because the policy statement displaced those regulations for construction work done on railroad bridges. (Velasquez, 734 F.2d at 218 n.l.) However, at the time of its decision, the Velasquez court did not have the benefit of the Railroad Administration’s 1991 interpretation of the policy statement. Because the Railroad Administration’s 1991 notice of proposed rulemaking contains an interpretation which is not plainly erroneous, we will follow the Railroad Administration’s interpretation rather than that of the Velasquez court. (Udall, 380 U.S. at 16-17, 13 L. Ed. 2d at 625, 85 S. Ct. at 801.) In light of the Railroad Administration’s 1991 interpretation of its own regulations, and the fact that Velasquez is distinguishable, we need not consider the question of whether Illinois courts are bound to follow the decisions of lower Federal courts when interpreting Federal law.
We are also aware that in 1988, Congress passed the Rail Safety Improvement Act of 1988, which requires the Railroad Administration to promulgate regulations “for the safety of maintenance-of-way employees, including standards for bridge safety equipment, such as nets, walkways, handrails, and safety lines.” (45 U.S.C. §431(n) (1988).) Defendant argues that this provision indicates that Congress believed that the Railroad Administration is the most appropriate agency to regulate employee safety on railroad bridges. Clearly, when the Railroad Administration issues its final regulations on this matter or indicates that the working condition should go unregulated, OSHA will be displaced from enforcing its corresponding regulations. However, the 1988 statute does not answer the question of whether, in 1984, the Railroad Administration had already made such a determination relative to this working condition. Moreover, we do not believe Congress intended this statute to displace OSHA regulations which would otherwise apply. Therefore, we find the Rail Safety Improvement Act of 1988 does not resolve the dispute in this case.
For the foregoing reasons, we reverse the judgment of the appellate court and remand to that court for consideration of the remaining issues raised by defendant’s appeal.
Reversed and remanded.