Opinion by

The defendant company was incorporated by a special act of assembly approved on the 6th day of April, 1859. There was at that time no system of general laws regulating the creation and defining the duties and obligations of such corporations. We must look therefore to the legislative action by which the new corporation was created for a statement of its powers and privileges, and for the extent to which it was subjected to municipal burdens in excess of those that fall upon all taxpayers alike. Turning to this act we find that the company was required to obtain the consent of councils to the use of the bridge on Bridge street, which was in the line of its prospective railway; -to conform to the established grade of the streets it should occupy; to keep the said streets in “perpetual good repair ” at its own expense; and to be subject to such ordinances as" councils might from -time to time adopt for the establishment of regulations “ in regard to paving, repaving, grading, culverting of, and laying gas and water pipes in and along said streets, and to prevent obstructions thereon.” It was not subjected to existing ordinances regulating the terms upon which the street railways were permitted to occupy the streets of the city, but the legislature laid out its route, named the streets to be occupied, and by virtue of its paramount authority gave to its creature permission to enter upon these streets and construct its line of railway upon terms named by it in the act of incorporation. The city seeks to recover for the cost of repaving portions of certain streets which the defendant was required to keep in good repair. The defendant denies its liability for new paving, while admitting its obligation to repair. The question thus raised depends upon the proper construction of the act of 1859 creating and defining the powers and duties of the defendant company. We are referred by the city in sup*376port of its position to that clause of the act subjecting the company to such regulations as might be made by city councils in-regard to paving, repaving, grading, culverting and laying gas and water pipes in the streets over which the tracks of the company might extend as affording the authority for charging the cost of repairing to the defendant. But this provision does not mean that the railway company may be required to pave, to repave, or grade, or lay water or gas pipe along all the streets it traverses with its railway, but that it shall not get in the way of'the city, and obstruct it in the prosecution of municipal improvements upon the city streets. It requires the railway company to conform to all regulations made by the city council having for their object the protection and facilitation of the work of the city in improving its streets, extending its system of water supply, or improving its system of drainage. When in any such direction the control of the city over its streets conflicts with the exercise of the franchise of the railway company on and over the same streets the latter must give way. The superior right of the city over its streets, as between it and any person or corporation doing business upon them, is thus recognized, and the corporation created by the act is by express words made subject to it: This precaution may not have been necessary, but it was wise. In 1859 the relations of the municipality and the street railway were not as well settled as they now are, and without this provision there was at least room for controversy over the right of the city to interrupt the exercise of a corporate franchise in its streets without liability to a claim for compensation.

This provision removes all doubt; the street railway, like the drayman, occupies the street subject to municipal control so far as this may become necessary for the public safety, or the prosecution of municipal improvements. The other ground on which a recovery is sought is that the railway was required by the law incorporating it to keep the streets occupied by it in good repair; the phrase to keep the streets in good repair, means to uphold, to maintain or preserve them in good condition ; it presupposes that they are in some fair degree of repair when the obligation to keep them so begins to operate. In this connection it should be noted that the requirement is not that the defendant shall put the streets in good repair but that it *377shall “ keep them ” in good repair. Whatever the style of paving might be at the time, the mode of repair must conform to it, and under the recent case of Phila. v. Ridge Ave. Pass. Ry. Co., 143 Pa. 444, it may be said that when the city repaves a street with a new and improved pavement the duty to repair relates to the pavement so put in place and requires that the repairs shall be adapted to the style of pavement which the city has placed, or caused to be placed, upon the particular street upon Avhich repairs are necessary. The duty to repair is a continuous one: It is for all time. It is not intended to perpetuate in each street of the city the style of pavement in use upon it when the railway company entered upon it with its trades: On the contrary the general supervisory control of the city over its streets is recognized, and its right to make such regulations in regard to paving, repaving, grading, culverting, and laying gas and water pipes along them, as may be desirable to facilitate its work, and to require obedience thereto by passenger railway companies as well as the cartman and footman, is clearly written into the charter of this company. The right of the city is to determine what pavement shall be used, and when it shall go down upon a given street; the duty to repair is upon the company wherever its tracks extend. A covenant to repair in a lease makes it the duty of the lessee to keep the buildings to which it relates in substantial repair, having regard to their age and condition at the time the covenant became operative.

It may sometimes require the restoration of an inclosure or other structure taken down or removed by the maker of the covenant, but in every case it refers to a previously existing condition, the restoration or preservation of which is the purpose of the covenant. This was substantially said as early as McClenahan v. Curwin, 3 Yeates, 362. It is the doctrine of all our cases. What' is now asserted is that the duty to repair includes the duty to replace with a new, an improved and more expensive stjde of pavement whenever the city shall so direct, and Phila. v. Ridge Ave. Ry. Co., 143 Pa. 444, and Phila. v. Thirteenth & Fifteenth Streets Ry. Co., 169 Pa. 269, are cited in support of this proposition. In neither of these cases was the question involved. In the latter case the company was subject to the ordinance of 1857 which expressly required it “ to be at the cost and expense of maintaining, paving and repairing,” the streets *378occupied by it. The same is true of the former, or Ridge Ave. Case; The Girard College Pass. Ry. Co. was by the act of April 15, 1858, made subject to the ordinance of 1857. It was merged into the Ridge Ave. Co. and this provision became a part of the law of the consolidated company, and was held to be binding upon it. The question was presented in Norristown v. Norristown Pass. Ry. Co., 148 Pa. 87, and decided in favor of the position of the appellant, by the affirmance of the judgment appealed from, in a short per curiam. The error of the learned judge of the court below in this case was in holding that the duty to repair was imposed by the provision in the defendants’ charter that recognized the right of the city to establish regulations in regard to paving, repaving, grading, culverting, and laying gas and water pipe in the streets. In so doing he followed what he believed to be the fair effect of the Ridge Ave. and Thirteenth & Fifteenth Streets cases above referred to, but in this he was mistaken. The first assignment of error is sustained. For the same reason the answer made to the first, second and third points of the defendant was erroneous. The law of this case is fairly stated in defendant’s fourth point. The extent of the liability of the defendant under its charter of incorporation is for the cost of repairs, properly made, to such style of pavement as may have been upon the several streets along which its railways ran when the notice to repair was given. The duty to repave was not imposed by the act of 1859. The judgment is reversed and a venire facias de novo awarded.