dissenting:
I respectfully dissent. In my view there is no competent evidence in the record before us to support the commission’s conclusions that the railroads and the City and County of Denver derive equal benefits from the viaduct, and that the assessment against Santa Fe and Burlington should be equally divided.
Although a reviewing court may not substitute its judgment for that of the PUC, it must determine whether there is competent evidence in the record to support the PUC’s decision. RAM Broadcasting of Colorado, Inc. v. Public Utilities Comm’n., 702 P.2d 746 (Colo.1985); Atchison, Topeka & Santa Fe Ry. Co. v. Public Utilities Comm’n, 194 Colo. 263, 572 P.2d 138 (1977). Similarly, while the findings and conclusions of the commission are presumed to be valid, and must be reviewed in the light most favorable to the commission’s decision, a PUC decision that is not supported by substantial evidence must be set aside. Home Builders Ass’n v. Public Utilities Comm’n, 720 P.2d 552 (Colo.1986).
Here, the commission concluded that Denver’s benefits of increased traffic flow are equal to the railroads’ benefits of increased speed over a surface crossing and the elimination of auto-train accidents that might occur at a grade-level crossing. However, the commission’s conclusion is based entirely on expert opinion testimony, primarily that of John Baier, Staff Transportation Engineer for the PUC. Baier’s testimony is comprised only of assumptions and conclusions, without any statistical data or empirical observations to support his opinions. For example, he did not provide the commission with data concerning the frequency of auto-train accidents at an at-grade crossing, with data concerning the added time the railways would save by a viaduct crossing, or with data concerning the railways’ exposure to liability resulting from an at-grade crossing. In sum, Baier’s “base case” methodology reaches the presumptive and unsupported conclusion that Denver and the railways benefit equally from the viaduct. Common sense dictates that the main benefit of the viaduct is better handling of traffic flow, a benefit to Denver only. Baier’s testimony assumed equal benefits instead of attempting to actually measure, quantify or document the benefits to Denver and the railroads, and then weigh the benefits of each party against each other.
In my view, therefore, the commission acted arbitrarily when it relied on Baier’s *1045conclusions rather than documenting and weighing the benefits to both parties as required by section 40-4-106(3)(c)(I), 17 C.R.S. (1984). The PUC’s conclusion that the railways derive as much benefit from the viaduct as does Denver is not supported by substantial or competent evidence.
Further, the commission disregarded a statutory directive when it allocated the cost assessment between Burlington and Santa Fe solely on the basis of track ownership. Subsection 40-4-106(3)(c)(II), 17 C.R.S. (1984), states: “In the allocation of class I railroad corporations’ share of expenses for a grade separation construction project pursuant to paragraphs (a) and (b) of this subsection (3), the commission shall consider the benefits, if any, which shall accrue between the class I railroad corporations affected.” (Emphasis added'.)
Disregarding the plain meaning of subsection 40-4-106(3)(c)(II), Baier failed to consider the respective benefits of the viaduct which would accrue to each railroad. He gave no consideration to the number of trains each railroad operated, the length of the trains, or the amount of increase in revenues each railroad would receive as a direct result of the construction of the viaduct.1 At the hearing, Baier admitted on cross-examination that he declined to consider the amount and volume of train traffic of each railroad and failed to consider the fact that Santa Fe only operates four trains a day under the viaduct. Again, the commission based its decision solely on Baier’s recommendations.2 In my opinion, by not considering the added benefits accruing between the two railroads affected, and by basing its decision solely on track ownership, the commission violated subsection 40 — 4—106(3)(c)(II). The 50% allocation of the costs to each railroad is nothing more than arbitrary and is not supported by any factual predicate.
Because I believe that the commission abused its discretion by rendering decisions unsupported by competent and substantial evidence, I would reverse and remand to the district court with directions to return the case to the Public Utilities Commission for further proceedings consistent with this opinion.
I am authorized to say that JUSTICE ROVIRA and JUSTICE KIRSHBAUM join in this dissent.
. An employee of Santa Fe testified at the hearing that on the average, Burlington operates six times as many trains under the viaduct as Santa Fe. Burlington’s trains are also much longer than those operated by Santa Fe. Because each railway retains the revenues and pays expenses in proportion to its wheel count, any allocation between the railways would have to recognize the dominance of Burlington’s use of the tracks under the viaduct.
. Despite undisputed evidence in the record demonstrating Burlington Northern’s more frequent use of the tracks under the viaduct, the commission concluded that “[b]oth railroads are equally responsible for and will equally benefit from the construction of the proposed viaduct.”