BURTON, J., dissenting. 353 U.S. but also that the stated objectives of the Acts would not be served by subjecting these vehicles to the Acts. The recognized purpose of each of the Safety Appliance Acts was the protection of operating employees of railroads from the hazards involved in the movement of standard trains and cars. The first Safety Appliance Act, 27 Stat. 531, 45 U. S. C. §§ 1-7, enacted in 1893, was preceded by a decade of concern, not with light maintenance equipment, but with the death toll caused by the two major hazards facing railroad trainmen: (1) the necessity for operating employees to work between freight cars in coupling them, and (2) the necessity for brakemen to operate hand brakes while standing on the tops of freight cars. The Interstate Commerce Commission, the railroad Brotherhoods, and other groups advocated legislation which would reduce these hazards by requiring uniform automatic couplers and power brakes on freight trains. Congress was concerned wholly with these hazards and the Act adopted relates entirely to them. 6 See S. Rep. No. 1049, 52d Cong., 1st Sess. 2-3, 5; H. R. Rep. No. 1678, 52d Cong., 1st Sess. 1, 3; 1 Sharfman, The Interstate Commerce Commission (1931), 246, n. 4. Since passenger cars, by 1893, had generally been equipped with the required appliances-train brakes and automatic couplers-they did not present the same hazards to trainmen. 7 The Commission recommended enactment of legislation in 1889 after completing a general investigation of railroad safety conditions. It continued to press for legislation until the enactment of the first Safety Appliance Act in 1893. See Interstate Commerce Commission Activities, 1887-1937 (1937), 118-120; Third Ann. Rep., I. C. C., for 1889, 44-45, 84-101; Fifth Ann. Rep., I. C. C., for 1891, 337-340; Sixth Ann. Rep., I. C. C., for 1892, 69-70. 8 The 1893 Act was entitled "An act to promote the safety of employees and travelers upon railroads by compelling common carriers engaged in interstate commerce to equip their cars with automatic couplers and continuous brakes and their locomotives with driving-wheel brakes, and for other purposes." The only provision 325 BURTON, J., dissenting. The present significance of these specific objectives is that they do not relate to motor cars and push trucks. Unlike standard railroad cars and trains, motor cars and push trucks do not require power brakes to bring them safely to a stop, and they do not endanger the section hands who couple them by pushing them together by hand. Operated and used by maintenance workers rather than by operating employees, motor cars and push trucks move at comparatively slow speeds and present hazards quite different from those faced by trainmen on standard trains. By 1900, the railroads were in substantial compliance with the original Act. Nevertheless, the Interstate Commerce Commission, disturbed because some locomotives and standard cars were not required to be equipped with automatic couplers, recommended broadening amendments. These recommendations called for automatic couplers for all locomotives and for "all vehicles . . . which are ordinarily hauled or propelled by standard locomotives." 10 The second Safety Appliance Act, enacted in 1903, 32 Stat. 943, 45 U. S. C. §§ 8-10, incorporated these recommendations. It extended the first Act to "all trains, locomotives, tenders, cars, and similar vehicles used on any railroad engaged in interstate commerce . . . and to all other locomotives, tenders, cars, and similar vehicles used in connection therewith (Emphasis sup plied.) Initially, the word "vehicles" in the bill was unqualified by the word "similar." S. Rep. No. 1930, 57th which might be thought to be unrelated to power brakes or automatic couplers was the requirement in §4 of "secure grab irons or handholds in the ends and sides of each car" and this requirement was expressly stated to be "for greater security to men in coupling and uncoupling cars." 27 Stat. 531, 45 U. S. C. § 4. • Fourteenth Ann. Rep., I. C. C., for 1900, 76. 10 Fifteenth Ann. Rep., I. C. C., for 1901, 68; Sixteenth Ann. Rep., I. C. C., for 1902, 61. BURTON, J., dissenting. 353 U.S. Cong., 1st Sess. 16. However, a railroad representative objected to it on the ground that it was too broad and suggested the term "traffic cars." Id., at 16-17. The legislative representative of the Brotherhoods opposed the suggested substitute because it might be thought inapplicable to "cabooses, steam shovels, snowplows, scale cars, and similar conveyances," which are used in connection with standard equipment. Id., at 46. The result was that the word "vehicles" was qualified by the addition of "similar." This indicates that the term "similar vehicles" was used to cover special equipment, such as snowplows, used in connection with standard equipment. Maintenance-of-way vehicles have never been capable of such use. The third Safety Appliance Act, 36 Stat. 298, 45 U. S. C. §§ 11-16, enacted in 1910, supplemented the existing Acts so as to require additional safety appliances, but did not extend the coverage. "Cars" were to be equipped with secure sill steps and efficient hand brakes; "cars" requiring secure ladders and running boards were to be so equipped; secure handholds or grab irons were to be installed on the roofs at the tops of such ladders; and the Commission was to designate the standards for these and certain other appliances, as well as to modify or change the standard height for drawbars. These additions grew out of recommendations made by the Commission and their history reveals an intent to secure uniform equipment on operating cars." Uniformity was considered to be imperative because trainmen working on trains by day and by night would operate more safely if the appliances they needed-sill steps, ladders, running boards, grab irons and the like-were uniform in character and location on all freight cars. Most 11 Twenty-third Ann. Rep., I. C. C., for 1909, 40-41; S. Rep. No. 250, 61st Cong., 2d Sess. 2; H. R. Rep. No. 37, 61st Cong., 2d Sess. 325 BURTON, J., dissenting. of these appliances are not at all adapted to motor cars and push trucks. On these small vehicles there not only is little or no need for this equipment, but there is no suitable place to attach it. The inapplicability of the Safety Appliance Acts to maintenance-of-way vehicles is confirmed by the longstanding administrative interpretation of the Interstate Commerce Commission and by numerous practical considerations. The Interstate Commerce Commission has administered these Acts for over half a century. During that time, it has, by its own statement, "never considered the small maintenance of way vehicles subject to those acts .. Its order of March 13, 1911, specifying the number, dimensions and location of the appliances required by the Acts, omits all mention of motor track cars and push trucks.13 Motor cars are not subjected to the inspection required of "locomotives." Maintenanceof-way vehicles are not considered as trains, locomotives or cars for accident reporting purposes.1 99 12 Despite the Commission's consistent construction of the Acts since their inceptions, the Court today states 12 "For over half a century, the Commission has administered the Safety Appliance Acts, as well as the other acts relating to railroad safety. During this period, the Commission has never considered the small maintenance of way vehicles subject to those acts, and we submit that the foregoing contemporary and legislative histories furnish a sound foundation for its view. That legislation is concerned with locomotives, cars and similar vehicles which employees were formerly required to go between to couple, or to ascend to use the hand brake. The acts are designed primarily to reduce or eliminate those hazards. They should not be construed to apply to entirely different types of equipment whose operation does not involve such risks." Brief of Interstate Commerce Commission, as amicus curiae, 18-20. 13 This order was amended in 1943 and republished in 1946. 49 CFR, 1949, Pt. 131. 14 See I. C. C., Accident Bulletin No. 124 for 1955, 94. BURTON, J., dissenting. 353 U.S. that "there has been no expressed administrative determination..." ." Ante, p. 330. Not only was there no reason for the Commission to disclaim application, but its "negative" action in declining to subject these vehicles to the Acts is impressive because the Acts impose an affirmative duty on the Commission to enforce their provisions.15 The Commission and the Department of Justice have been aware that motor cars and push trucks used by American railroads were not equipped with automatic couplers, power brakes and so on. Their failure to prosecute evidences their interpretation of the Acts. Federal Trade Commission v. Bunte Brothers, Inc., 312 U. S. 349, 351-352. The contemporaneous and long-standing interpretation of any regulatory Act by the agency that administers it is entitled to great weight.16 Here there are considerations entitling the Interstate Commerce Commission's views to special respect. See Davis v. Manry, 266 U. S. 401, 404-405. The Commission has played a predominant role in developing and perfecting the Acts, and Congress has given it broad discretionary powers in administering them. Its consistent interpretation of the Acts, known to Congress, the railroad industry and the railroad labor organizations, is persuasive evidence that the Acts never were intended to apply to motor cars and push trucks.17 15 Under $6 of the original Safety Appliance Act, 27 Stat. 532, 45 U. S. C. § 6, and §§ 5 and 6 of the third Safety Appliance Act, 36 Stat. 299, 45 U. S. C. §§ 14 and 15, the Interstate Commerce Commission has the mandatory duty of informing United States District Attorneys of violations of the Acts; these attorneys have the mandatory duty to prosecute violators; and railroads are liable for a penalty of $100 for each violation. 16 See, e. g., Norwegian Nitrogen Products Co. v. United States, 288 U. S. 294, 311-315; Wisconsin v. Illinois, 278 U. S. 367, 413. 17 The two federal court decisions relied on by the Court are distinguishable. The 18-foot gasoline tractor which was held to be |