dissenting.
I dissent. Unlike the majority and the Commonwealth Court, I view the City of Pittsburgh’s “Petition for Review” seeking interest on the sum PennDOT reimbursed the City as an impermissible effort to enlarge the order of the PUC directing PennDOT only to reimburse the City and not to pay the City interest. Thus I would hold that the Commonwealth Court erred in awarding the City interest on the sum PennDOT reimbursed.
In August of 1972, the PUC ordered the City to demolish and reconstruct a city bridge carrying traffic over tracks of the Baltimore and Ohio Railroad Company. The City was to perform the demolition and reconstruction work initially at its own expense. The PUC directed, however, that after the City performed the work PennDOT was to pay fifty percent of the actual cost of materials and work, “when and as certified” by the PUC. Nothing in this initial order even purports to suggest the City is entitled to interest on Penn-DOT’s allocable share. The City took no appeal from the PUC’s determination.
In October of 1974, the PUC certified PennDOT’s share of City costs at $667,139.19. Again, however, this order does not suggest PennDOT is to pay the City interest. As with the previous order, the City never questioned this order in any respect.
PennDOT believed the PUC’s certification order improperly included certain costs incurred before the PUC ordered demolition. After negotiations with the City proved unsuccessful, PennDOT petitioned the PUC to open the record and permit a reduction of PennDOT’s allocable share. After a hearing, in July of 1976 the PUC agreed in part with PennDOT and entered a revised order certifying PennDOT’s share of costs at $655,731.75. As with the previous PUC orders, however, nothing in this revised order indicates PennDOT is to pay the City interest on the sum reimbursed. The City again took no appeal.
*273PennDOT did not immediately reimburse the City only because it believed then, as it believes now, that the Legislature first had to approve the demolition and rebuilding project. Nonetheless, the City began its efforts to compel reimbursement by way of judicial proceedings. Nothing on this record indicates that the City sought either the PUC’s or the Attorney General’s enforcement of the revised PUC reimbursement order. See Public Utility Law, Act of May 28, 1937, P.L. 1053, §§ 903 & 904, 66 P.S. §§ 1343 & 1344 (1959). Instead, the City proceeded directly against Penn-DOT by filing a Petition for Review in the Commonwealth Court. The City’s petition sought not only an order directing PennDOT to pay the principal sum of reimbursement but also interest from October, 1974, the date of the original, subsequently revised PUC order.
While the City’s Petition for Review was pending, the Legislature approved the demolition and reconstruction project. PennDOT, which had been awaiting legislative approval, immediately made payment. The City, however, persisted in its request for interest on the sum reimbursed.
On the City’s motion for judgment on the pleadings, the Commonwealth Court agreed with the City that its request for interest is justified under the “damages” provision of section 16 of the Mandamus Act of 1893, Act of June 8,1893, P.L. 345, 12 P.S. § 1919 (1967). Section 16 provides:
“If a verdict is found for the plaintiff and judgment is entered thereon, or if a judgment is given for him upon a demurrer, or by nihil dicit, or for want of an answer, by non sum informatus, or other pleading, he shall recover his damages and costs.”
According to the Commonwealth Court, under this section the City may recover interest on the revised sum of $655, 731. 75 as “an incident of the main recovery sought against the Commonwealth.” The Commonwealth Court held, however, that interest is available only from July, 1976, the date the PUC entered its revised certification order. Thus it *274denied the City’s request for interest from October, 1974, the date of the PUC’s first certification order.
The majority now upholds the Commonwealth Court’s award of interest from July, 1976, the date of the PUC’s revised certification order. The majority also holds, however, that the Commonwealth Court erred in denying the City interest from October, 1974 on the principal sum of $590,438. The majority concludes that PennDOT’s failure to question its obligation to pay this amount of principal requires PennDOT to pay interest.
Fundamental to the error of both the majority and the Commonwealth Court is their acquiescence in the City’s view that only the Mandamus Act of 1893 is relevant to the propriety of the City’s present action. The City’s action, here a Petition for Review pursuant to Pa.R.App.Proc. 1501 et seq., in reality seeks enforcement of the PUC’s revised certification order. Nothing in the Public Utility Law expressly gives the City authority to enforce a PUC order. Power to obtain enforcement of PUC orders is specifically conferred only upon the PUC and the Attorney General. See Public Utility Law, §§ 903 & 904, 66 P.S. §§ 1343 & 1344. Surely if the City cannot bring the present enforcement proceeding it cannot seek the supplemental relief of interest on the principal sum the PUC ordered PennDOT to pay.
Even if the City has authority to obtain enforcement of the PUC’s revised certification order, there remains the issue of whether, by way of the present petition for review, the City can enlarge the scope of the PUC’s revised certification order to include the previously unincluded subject of interest. Sound, general principles of administrative jurisprudence suggest otherwise. The PUC’s orders directing reimbursement are final and thus to be accorded the same res judicata effect paid any other judgment. See Restatement (Second) of Judgments, § 131 (Adjudication by Administrative Tribunal) (Tent. Draft No. 7, 1980). Moreover, nothing *275in sections 903 and 904 of the Public Utility Law would permit either the PUC or the Attorney General to enlarge the PUC’s order of enforcement to include interest. Far from permitting supplemental relief of interest to be entered, section 903 permits a court to enter a writ of mandamus compelling compliance with the extant order “in such modified or other form as will afford appropriate relief.” Surely it cannot be contended that a party such as the City, not mentioned in the Public Utility Law as a proper enforcing party, can accomplish any more by way of the general language of the Mandamus Act of 1893 than can those governmental bodies statutorily authorized to enforce a PUC order.
Finally, there is the “well-settled rule that a sovereign state is not liable for interest in any case except where, expressly or by reasonable construction of a contract or statute, it has placed itself in a position of liability.” Purdy Estate, 447 Pa. 439, 442, 291 A.2d 93, 95 (1972). This rule is especially appropriate where, as here, one governmental body is seeking to compel another governmental body to pay interest. Nowhere in the relevant cost-allocation statute, Public Utility Law, § 411(a), 66 P.S. § 1181(a), or anywhere else does the Legislature even suggest that an award of interest against the Commonwealth is appropriate in this class of litigation. Indeed, an award of interest would mean only that one governmental body would be obliged to pay tax dollars to another. I cannot impute to the Legislature the intent to permit such an untoward result.
The majority suggests that this Court’s repudiation of sovereign immunity in Mayle v. Pennsylvania Department of Highways, 479 Pa. 384, 388 A.2d 709, reargument denied, 479 Pa. 411, 390 A.2d 181 (1978), somehow calls into question the rule of Purdy. In Mayle, this Court lifted the bar against trespass actions by private citizens against the Commonwealth. This case, however, unlike Mayle, involves a dispute between branches of local and state governments. *276However this Court now in light of Mayle might view a case involving a private party seeking interest against the Commonwealth, an issue on which I express no view, I do not believe the rule of Purdy should be changed or qualified on these facts.*
For these reasons, that portion of the order of the Commonwealth Court awarding interest should be reversed and that portion denying interest affirmed.
I cannot subscribe to the majority’s additional suggestion that Penn-DOT’s supposed unreadiness to pay the City justifies an interest award here. The record is clear that PennDOT has always been ready to pay the City. It did not do so immediately only because of its continuing belief that legislative approval of project expenditures was necessary before it could make reimbursement.