delivered the opinion of the Court:

1. The first point of appellants’ contention is, that the Commissioners are wholly without the power to make police regulations affecting their respective railways because Congress, in the acts permitting them to enter the District of Columbia, expressly reserved that power to itself to be exercised by direct action. This is founded in the clause contained in each of said acts, reserving “the right to enact such rules and regulations prescribing the speed of cars or carriages passing over said road, and any other matters relating thereto necessary for the security of the persons and property of the inhabitants of the District, in such manner as the present or any future Congress shall deem expedient.”

The ordinary power of police regulations of the exercise, by the grantees, of the franchises conferred, required no reservation to preserve its existence; nor could it have been *125surrendered or contracted away by the express grant, even, of one Congress so as to bind its successors. The foregoing provision, however, contains no element of a grant or contract; it is a reservation, wholly unnecessary, that seems to have been inserted out of abundant caution merely, and for no other purpose. We find nothing in its language expressive of an intent to reserve the exercise of such power to Congress by direct act exclusively, or to preclude its delegation. by reasonable implication, to the ordinary municipal authorities of the District.

2. The question next occurring is, whether Congress has delegated this power to the Commissioners to the extent exercised by them in the adoption of the regulations aforesaid, and particularly of section 17 thereof?

Though differing in many important, respects from the ordinary municipal governments in existence thoughout the country, the local government of the District of Columbia is nothing less than a municipal corporation. Metropolitan R. Co. v. District of Columbia, 132 U. S. 1, 7; Eckloff v. District of Columbia, 135 U. S. 240, 243.

The Commissioners are the governing body, with duties chiefly executive; but they may and do exercise certain powers of local legislation or municipal regulation under the direction of Congress. The subject-matter of these regulations and the manner of their enforcement are either indicated in, or to be necessarily implied from, express delegations of authority.

An act of Congress, approved January 26,1887, conferring upon the Commissioners the power to make certain police regulations, contained the following, among other clauses, in section 10: “To regulate the movement of vehicles on the public streets and avenues'for the preservation of order and the protection of life and limb.” 24 Stat. 368.

We agree with the appellants that railroad locomotives and cars are not within the meaning of the word “vehicles” as used in the foregoing clause. They may, no doubt, be *126regarded as vehicles in a strained sense, and therefore held to be comprehended in the word when such an intention can be reasonably gathered from the context; but they are not within its usual and ordinary signification.

We are clearly of the opinion, however, that the power to regulate the movements of railway locomotives and trains was conferred upon the Commissioners by the joint resolution of Congress, approved February 26, 1892, which reads as follows: “ That the Commissioners of the District of Columbia are hereby authorized and empowered to make and enforce all such reasonable and usual police regulations, in addition to those already made under the act of January 26, 1887, as they may deem necessary for the protection of lives, limbs, health, comfort and quiet of all persons and the protection of all property within the District of Columbia.” 27 Stat. 394.

The contention on behalf of the appellants, that this resolution confers no new powers not authorized by the former act, and must be limited by construction to such other and further regulations only as may be of the class enumerated therein, is without foundation.

The resolution is so general, and so comprehensive in its terms, that had it been incorporated into the act of 1887, as the concluding clause of section 10, its operation could hardly be limited by the scope of the specific grants of power preceding it. But, enacted after five years of experience under the old law and in express addition to the powers therein conferred, we think it clear that Congress intended thereby to increase the powers of the Commissioners to the full extent of those frequently, if not generally, entrusted to municipal corporations. Upon no other theory can its passage be reasonably accounted for. And instead of entering into details, as in the former act, the grant of the power to make usual and reasonable police regulations was expressed in the broadest terms.

3. That regulations requiring steam railroad trains to be *127stopped before crossing other railroads operated by steam» cable and electricity, are usual in other cities of the country, is positively averred in the answers of the Commissioners, and must be accepted as true. Such regulations have certainly been made and enforced in other jurisdictions in respect of the crossing of one steam railroad by another at grade, and in country as well as in cities, and their reasonableness has, so far as we have been able to discover, always been upheld. L. S. & C. R. Co. v. C. S. & C. R. Co., 30 Ohio St. 604, 617; M. & O. R. Co. v. The People, 29 Ill. App. 428; State v. Noyes, 47 Me. 189, 201.

4. Whilst the courts have the undoubted power to inquire into the reasonableness of municipal regulations that affect the free exercise of the ordinary rights of persons and property, when sought to be enforced, they will not declare them invalid save in plain cases of usurpation of power or of abuse of discretion.

The use of all property, more especially that situated or used in the public streets, is subject to the exercise of the power of reasonable police supervision and regulation, for the protection of the public health and safety. And what may, and what may not, be a reasonable requirement in one case, cannot be determined by a fixed rule applicable alike to all; but must, of necessity, depend upon special circumstances and the exigencies of the situation, to meet which the regulation may have been adopted. Every such regulation may be, and often is, inconvenient, burdensome and oppressive in a certain sense; but it does not follow that, by reason of such consequences alone, it must be declared beyond the power and discretion of the legislative authority. To compel the appellants to stop their trains at the crossings, as required by the regulation in question, will cause them inconvenience, and, no doubt, work irksome delays in the passage of their trains through the city of Washington ; but these requirements do not appear to be so oppressive, necessarily, as to require them to be declared *128unreasonable when considered in connection with the paramount duty with which the Commissioners are charged in respect of the protection of the lives and property of the people who are also entitled to the use of the streets, subject only to similar restrictions. Regulations apparently far more burdensome than this — for example^ compelling steam railway companies to substitute horse power for steam, within certain limits — have been declared by the Supreme Court of the United States not to be unreasonable or in violation of private right. Railroad Co. v. Richmond, 96 U. S. 209.

In a recent ease in that court, in which a State police regulation was assailed by a railway company engaged in interstate commerce, it was said : “The well settled rule is, that if a statute purporting to have been enacted to protect the public health, the public morals, or the public safety, has no real or substantial relation to those objects, or is a palpable invasion of rights secured by the fundamental law, it is the duty of the courts to so adjudge.” Hennington v. Georgia, 163 U. S. 299, 303, 304.

And it follows, necessarily, that unless these conditions are palpable, the courts cannot so adjudge.

Now, in a case where the question of the invasion of private rights is one more of law than fact, or where the facts are susceptible of reasonably certain proof, courts may give slight weight to the judgments of the municipal authorities, and presume little in their support beyond good intentions and integrity of action in the premises. But in a case like the present, where thequestion isoneof practical fact, unsettled by experience, and resting in opinion, a court should surely hesitate to set up its judgment in opposition to that of the municipal officers, who, by virtue of their training, observation and experience in the performance of their duties, ought to be well informed and capable of arriving at satisfactory conclusions in such matters.

Had the appellants undertaken to obey the regulation, in *129good faith, and to give its operation a fair test before engaging in litigation to- prevent its enforcement, we might have had abundant evidence before us by which the question of its reasonableness, under all the surrounding circumstances, could readily be determined. As it is, however, we have no satisfactory proof that would justify us in overruling the action of the Commissioners in the course of a duty imposed upon them and entrusted to their special discretion, and in the discharge of which they must be presumed to be actuated by the only motive that should control the conduct of public officers.

5. There are some affidavits accompanying the bills which tend to show that at certain crossings where stops are compelled to be made, long tains that may cover two street crossings at the same time cannot be stopped, under constantly occurring conditions, as required in section 17, and started again within the limit of two minutes beyond which., as provided in section 19, cars cannot be allowed to stop on any street crossing. On this foundation, the argument is made that section .17 must be declared unreasonable because obedience to its requirements will necessarily cause the violation of section 19. The Commissioners, in their answer, say that this difficulty (which they do not admit the probability of) may be readily obviated by dividing up and thus shortening the trains so as to prevent their covering more than one crossing at the same time. As regards this, however, we are not prepared to say,'from the facts before us, that the suggested remedy would or would not prove unreasonably burdensome and oppressive.

As it is not certain that there will be this inevitable conflict in the enforcement of the two sections, the objection to section 17, founded thereon, cannot be regarded as well taken. Moreover, section 17 is the leading and important one of the series of regulations, and has relation to the safety of life and property, while section 19 relates merely to the public convenience in the use of the streets. Section 17 is the one *130directly involved in this case, for under it the prosecutions have been maintained; and the consideration of section 19 is incidental merely.

If the alleged conflict in the operation of the two sections were conceded, it would not necessarily follow that both regulations should at once be declared unreasonable and invalid. Upon its becoming manifest, the Commissioners would, no doubt, immediately make the necessary changes in section 19 to accommodate it to the other. Nor can we.assume that, in a prosecution in the Police Court for the violation of section 19, that court would fail to hold it a complete defence if it should be made to appear that the said violation was the necessary result, under prevailing natural conditions, of obedience to the commands of section 17.

6. The records of the cases of Bowler and Kindle contain no facts, and in accordance with the stipulation of counsel, the records in the equity cases of the two railway companies have been resorted to for the facts necessary to the determination of the .validity of the seventeenth section of the regulations, which alone is involved in the two first cases. From the bills, answers, and affidavits in the last two cases, the preliminary statement and the facts adverted to in the opinion have been taken, and it is therein that regulations other than section 17 aforesaid have been brought to our attention.

Considered in the light of these facts, we have found no error in the judgments below remanding the appellants, Bowler and Kindle, to the custody to which they were committed in default of the payment of the fines imposed upon them for the violation of the regulation, section 17, and they must each be affirmed, with costs.

The only question presented in the equity appeals that is not involved in the other cases, is one of jurisdiction, and the decision of that is now wholly unnecessary, because, whatever view might be taken of it, the decrees dismissing the bills must necessarily be affirmed. Leaving open, there*131fore, the important question whether a court of equity has jurisdiction to enjoin the enforcement of a police regulation through prosecutions duly carried on in a court of competent jurisdiction, and where no attempt is made to enforce the sqme by the forcible invasion of or trespass upon property, the decrees appealed from by the Baltimore and Ohio Railroad Company and the Baltimore and Potomac Railroad Company, respectively, must be affirmed, with costs; and it is so ordered. Affirmed.