I. In 1914 the mayor of the city of St. Joseph filed four complaints to the Public Service Commission against various railroad companies and the St. Joseph Street Railway Company, looking to the removal of dangerous street-level crossings. From the order of the Commission apportioning the cost of grade-crossing eliminations to the various companies,' an appeal was taken to the circuit court of Cole County by the Street Railway Company. The order was reversed and the cause remanded and from that judgment the Public Service Commission has perfected an appeal to this court.
The plan finally adopted by the Commission for the elimination of the various dangerous grade crossings was agreed to and accepted by all of the railroad companies, and the controversy here is over the amount apportioned to be paid by the Street Railway Company as its share of the total cost.
The Public Service Commission found the total cost of the improvement and subtracted therefrom the estimated consequential damages to private property and apportioned it to be paid by the city. It then allotted the balance to be paid by the railroad companies, which then undertook to meet at Chicago and agree as to the proper apportionments inter sese. As á result of that meeting one-seventh of $238,000, or $34,000, was allotted to be paid by the Street Railway Company and the remainder of the Cost of the improvement was to be borne by the steam railroad companies.
The Street Railway Company being dissatisfied with this charge against it, filed a motion before the Public Service Commission to re-apportion the cost of the improvement as between it and the other railroad companies. Upon the hearing of that motion it was shown by the testimony of various engineers that the *649methods usually employed to reach' an adjustment of cost in such cases are what are termed the “trackage basis” and the “right of way basis;” that in this instance it was found impracticable to use the “right of way basis,” and that the “trackage basis” (by which the estimate of $34,000 was made at the Chicago conference) was fair and reasonable. At this hearing it was further shown that the Street Railway Company would receive certain benefits from the removal of specified grade crossings equal to that accruing to any one of the steam railroads; but that the steam railroads, in addition to bearing their proportionate part of the cost of subways and track raising, would have to bear also the further expense- of installing an interlocking plant and acquiring considerable right of way.
On the other hand the Street Railway Company insisted that it should be required to pay only $12,500, the estimated cost of the work to be done within the Street Railway Company’s track zone.
In estimating a fair apportionment of the amount to be paid by the Street Railway Company, the Public Service Commission then took into consideration certain other elements of constructive cost’ and benefit of the general improvement and did not base its conclusion solely upon the “trackage basis” by which the cost was apportioned by the conferring railroads at their Chicago conference. In following this plan the Commission took the evidence of its own engineers and experts, as well as the testimony of persons present and taking part in the Chicago conference, and as a result estimated the amount properly chargeable to the Street Railway Company at $46,569, from which sum it deducted $12,000 to cover the benefits that would accrue to the steam railroads by doing away with the expense of crossing watchmen, thus leaving the amount allotted to the Street Railway Company $34,569, or $569 more than the estimate under the “trackage basis,” of which the Street Railway Company was complaining in its motion.
*650 Powers of commission.
*649II. In the performance of its duties the Public Service Commission derives its powers to act from the *650terms and intendment of the legislative enactments which' created that body. [Laws 1913, p. 556.] Section 50 of that law invests the Public Service Commission with “exclusive power” as to ^ installation, alteration or removal of the crossings ■ of highways by railroads and street railroads, and “to require, where, in its judgment, it would be practicable, a separation of grades at any such crossing heretofore or hereafter established, and to prescribe the terms upon which such separation shall 'be made and the proportions in which the expense of the alteration or abolition of such crossings or the separation of such grades shall be divided between the railroad or street railroad corporations affected or between such corporations and the State, ■ county, municipality or other public authority in interest.” [Laws 1913, p. 589, sec. 50.] It was entirely competent for the Legislature to delegate these functions to a trained body of experts, since they do not involve the exercise of the exclusive .power of lawmaking which a Legislature cannot part with. [Public Serv. Comm. v. Union Pac. Ry. Co., 271 Mo. 258, par. 2.]
It cannot be doubted prior to this statute that full power inhered in the State and its auxiliaries in government, such as municipalities, to require separation of the grades at crossings and to impose the entire expense thereof upon an occupying railroad, upon the theory that the permission to cross a highway given to a railroad, is upon the basic condition that it shall be restored, upon the cessation of such occupancy, either by the act of the railroad or in conformity with directions emanating from the State in the exercise of its sovereign powers of police, so as to be safe and convenient for use by the public. [Am. Tob. Co. v. St. Louis, 247 Mo. l. c. 433 et seq., and cases cited.]
And it cannot be doubted that independently of the provisions of the subsequent, acts of the Legislature quoted above, the costs and expenses of the elimination of grades and the restoration of the highway might have been imposed wholly upon the railroads under a valid ordinance of the city of St. Joseph. But the fur*651ther contention of the learned counsel for respondent, that the Public Service Commission was not authorized under the section of the statutes upon which its action in this matter'is predicated, to charge such proportion of the expense to the Street Railway Company, loses sight of the plain language and intent of the statute giving the Public Service Commission “exclusive poiver’’ to act in such matters and vesting it with complete authority to make an allotment of the expense among other parties in interest than the railroads, and' overlooks the further fact that the statute makes it the duty of the Public Service Commission to apportion the expense of crossing eliminations “between state, county, municipal or other public authority in interest.” These provisions are modifications of the common by the positive law, by expanding its principles so as to fit the conditions arising in social and industrial progress and to apply to them a fuller and more enlightened justice than was afforded under the narrower view of the common law enunciated at a time when there were fewer diversities of interest to be affected by removal of railroad crossings. In order to be a perfect scheme of social justice, the law must grow and expand to meet the diversified interests which increase as society advances.
We can see no reason why such a statutory modification and reformation of the common law should be subject to any constitutional or legal attack. It is the duty of an intelligent law-making body, in the exercise of its constitutional power, to alter, modify or abolish any rule of the common law which has become obsolete or unequal to the demands of social advancement, and to substitute by statute more refined rules of justice than were afforded by the cruder customs of early stages of society.
Our conclusion is that there is no merit in the contention that the Public Service Commission did not have plenary power to apportion among all the parties in interest, including the street railway company as well as the city and the steam railroads, the cost and *652expense of the general improvements for the safeguarding of the public by its order eliminating the grade crossings in the city of St. Joseph.
Reasonable Apportionment. III. The only question left is the reasonableness and justice of the apportionment made by the Public Service Commission as far as it involved the charge of $34,569 against the com- . . . . , mi i i plaining street railway. The learned counsel for respondent insists correctly that this should be determined after a review of the evidence, all of which- is before us, as in the trial of suit's in equity. [Railroad v. Pub. Serv. Com., 266 Mo. l. c. 341; s. c. In Banc, Unanimous Per Curiam on Rehearing, l. c. 346; Lusk v. Atkinson, 268 Mo. l. c 117, 118; State ex rel. v. Pub. Serv. Com., (Sep. Concurring Opinions of Bond, Graves and Woodson, JJ.), 271 Mo. 155 (l. c. 161, 165, 167).] It is further contended that when this is done the street railroad company should not be charged with a greater sum than fifteen thousand dollars, and in fact, on the last page of his brief, the learned counsel for respondent insists that the judgment of the circuit court should be affirmed and the cause remanded to the Commission “with directions to the Public Service Commission to make an apportionment on an equitable basis by apportioning to the street railway company . . . the expense,” etc., not to exceed $15,000. It is apparent, therefore, that the final contention of the respondent street railway company is not that no part of the expense necessarily incident to .the general improvements, should be apportioned to it, but only that the Public Service Commission made an excessive apportionment. We are not prepared to com cur in that view. After a careful and painstaking' review of the relevant testimony in the record before us, we have been unable to reach the conclusion that the finding of the Public Service Commission is not sustained by the clear preponderance of the testimony as to the proper method of making such an apportionment and the proper amount to be borne by the street railway company.
*653It necessarily follows that the learned circuit judge fell into error in setting aside the order of the Public Service Commission. His judgment in so doing is, therefore, reversed and the proceeding remanded, and the order heretofore made by the Public Service Commission is affirmed. It is so ordered.
All concur; Blair, J., in separate opinion in which Williams, J., joins.