We find the history and statement of facts in our decision of May 7, 1979, to be correct in all material respects. We therefore adopt the history and statement of facts and will not repeat them except where necessary to clarify our discussion. While we stand by the findings in the declaratory order of May 7, 1979, we believe that the issues raised by Miami indicate that a certain degree of confusion and uncertainty remain on its part. We will address those issues and elaborate the reasons underlying our previous findings.

DISCUSSION AND CONCLUSIONS

I

The first argument raised by Miami is found in its preliminary statement. There it is argued that unless a line extension or an abandonment application is before the Commission, it lacks jurisdiction to determine whether a given track or facility is a line of railroad. Miami cities Texas & P. Ry. Co. v. Gulf, C.&S.F.R. Co., 270 U.S. 266 (1926), as the leading case standing for that proposition.

Miami also states that besides lacking jurisdiction, the Commission may not even consider the character of trackage because it is a mixed question of fact and law reserved for judicial determination. United States v. Idaho, 298 U.S. 105, 109 (1936). On both of these points Miami misinterprets the holdings of the Supreme Court. In Texas & P. Ry., supra, the Court decision simply stated that the sole remedy for a party seeking to prevent an unlawful track extension is a court injunction, and that the court in considering the requested relief may determine the character of the track. We wish to emphasize, however, as we did in our prior decision, that nowhere in the Texas case did the Supreme Court state that the Commission lacked jurisdiction to determine the status of the track.

Regarding the holding of United States v. Idaho, supra, a thorough reading reveals that the Supreme Court did not intend to deny the Commission the authority to pass upon the status of railroad track. Justice Brandeis, writing for the Court, stated clearly at page 109 that the Commission's determination would not be final.

For whether certain trackage is a "spur" is a mixed question of fact and law left by Congress to the decision of a court; not to the final determination of either the federal or a state Commission. [Emphasis supplied.]

Had the Court intended to deny the Commission the right to render any determination on the status of track, it would have stated so. In Shields v. Utah Idaho R. Co., 305 U.S. 177 (1938), at page 185, the Supreme Court interpreted United States v. Idaho, supra, to mean that the "*** Interstate Commerce Commission was denied the authority to determine the character of trackage ***." This interpretation was dicta which was subsequently modified in City of Yonkers v. United States, 320 U.S. 685, 689 (1944). There, the Court's opinion stated:

As stated by Mr. Justice Brandeis in United States v. Idaho, 298 U.S. 105, 109 (1936), the determination of what is included within the exemption of 1(22) involves a "mixed question of fact and law." Congress has not left that question exclusively to administrative determination; it has given the courts the final say. [Emphasis supplied. I

In a more recent case, State of Illinois v. United States, 213 F. Supp. 83, 88 (N.D. III. 1962), affirmed 373 U.S. 378 (1962), reh. den. 374 U.S. 858 (1963), the court also interpreted United States v. Idaho, supra. There it held that the Idaho case merely concluded that the ultimate decision was left to the courts and not to the Commission." [Emphasis supplied.]

****

The rationale for the above interpretation is predicated upon the need to make use of the Commission's expertise in the area of transportation. As so aptly stated by Justice Douglas in City of Yonkers v. United States, supra, at 692, “It also gives the reviewing courts the assistance of an expert judgment on a knotty phase of a technical subject." See also Board of Trade v. United States, 314 U.S. 534, 548 (1942), Interstate Commerce Commission v. Memphis Union Station Company, 360 F. 2d 44 (6th Cir. 1966), 50 (1966), cert. den. 385 U.S. 830 (1966), and Trans-American Van Service, Inc. v. United States, 421 F. Supp. 308, 329 (N.D. Texas 1976).

II

Miami also avers that the declaratory order process used by the Commission pursuant to 5 U.S.C. 554(e), and in accordance with our general or implied authority, is inapplicable to the proceeding at hand. It is argued that 5 U.S.C. 554(e) is limited by 5 U.S.C. 554(a) which precludes the issuance of a declaratory order where a case is not required by statute to be determined on the record after opportunity for an agency hearing or where the case is subject to a subsequent trial de novo.

In our prior decision we found that 49 U.S.C. 10904(c)(1) requires the Commission to hold a hearing in a contested abandonment proceeding. We stand by that finding.

The case law cited by Miami in support of its position that there is no statutory requirement for a hearing, in such a case, rests upon an interpretation of the Interstate Commerce Act, former section 1(19), which was repealed by Public Law 94-210, the Railroad Revitalization and Regulatory Reform Act of 1976 (4R Act).' It is Miami's contention that the 4R Act did not alter the discretionary nature of hearings in abandonment proceedings.

Miami's argument is incorrect and fails to take cognizance of the changes brought about by the 4R Act. As presently codified at 49 U.S.C. 10904(c)(1), the statute states that the Commission shall upon petition *** cause an investigation to be conducted to assist it in determining what disposition to make of an application for abandonment. The intent of Congress could hardly be clearer. See Marathon Oil v. Environmental Protection Agency, 564 F. 2d 1253, 1262-64 (9th Cir. 1977). The word "shall" as used in the statute, is of an imperative nature which does not allow for discretion. If a petition to investigate is filed, the Commission must institute an investigation. However, the extent and format of the investigation is left to the Commission's discretion. That discretion merely means that one investigation may be more formal or broader in scope than another.

The particular manner in which the Commission exercises its discretion depends upon a number of variables, such as the number and quality of the petitions to investigate, the complexity of the involved issues, and the potential impact of the abandonment. Once these initial issues are clear, the Commission will set the abandonment proceeding for a hearing on a paper record consisting of sworn statements or on oral hearing. See 49 CFR 1121.36(a)(1)(v).

We therefore conclude that an investigation in an abandonment proceeding is an evidentiary proceeding, required by statute to be determined on the record after an agency hearing. This process complies with the provisions of 5 U.S.C. 554(a), and a declaratory order is proper.

'The cases cited by Miami are: Brotherhood of Locomotive Engineers v. United States, 217 F. Supp. 98, 100 (N.D. Ohio 1963) and Commonwealth of Pennsylvania v. United States, 361 F. Supp. 208, 213 (N.D. Pa. 1973), affirmed per curiam, 414 U.S. 1017 (1973).

III

Miami also argues that in any proceeding, even if the Commission does render a decision on the merits, the threshold jurisdictional issue is subject to a de novo review because a question of jurisdiction is for the courts and not the Commission's determination. We have already addressed this issue in answering Miami's argument as set forth in its preliminary statement. It is sufficient to say that Miami is incorrect, and that the jurisdictional issue is properly reviewed upon the record by the courts. City of Yonkers v. United States, supra at 330.

IV

In our decision of May 7, 1979, we held that the Commission may also issue declaratory orders pursuant to our general or inherent jurisdiction. Miami states that the Commission has no inherent jurisdiction in such a proceeding.

In Permian Basin Area Rate Cases, 390 U.S. 747 (1968), cited by the Commission in Winnebago Farmers Elevator Co. v. Chicago & N. W., 354 I.C.C. 859, 863 (1978), the Supreme Court held that a regulatory agency must have a good measure of inherent authority so that it may accomplish its functions.

The decision at page 776 states:

The Court has repeatedly held that the width of administrative authority must be measured in part by the purposes for which it was conferred ***. Surely the Commission's broad responsibilities therefore demand a generous construction of its statutory authority.

See also American Trucking Association v. United States, 344 U.S. 298 (1953) and Ex Parte No. MC-43 (Sub-No. 7), Lease and Interchange of Vehicles, 129 M.C.C. 700, 702-03 (1978), 49 CFR, 1057.

In view of the cited case law, it is beyond question that the Commission has inherent authority and that it may use this authority to resolve a controversy. The present controversy between F.E.C. and Miami, regarding the status of the P&O Dock facility and whether it is subject to Commission jurisdiction, is a perfect example of a situation in which we may use this authority to resolve a controversy.

V

The last substantive argument raised by Miami revolves around the doctrine of res judicata. It is asserted that both the Federal District Court and the State court found the railroad tracks in question to be spur tracks rather than a line of railroad. Therefore, it is argued, the Commission should have accorded those court decisions res judicata effect.

Miami's argument ignores the holding of both courts. As noted in our prior decision, the United States District Court for the Southern District of Florida in Case No. 78-258-Civ.-SMA, Florida East Coast Railway Company v. City of Miami, simply stated that it had no jurisdiction over the proceeding since F.E.C. lacked standing. We emphasize that the Federal District Court never issued a ruling as to the status of the P&O Dock and the railroad tracks.

In the eminent domain proceeding, the Circuit Court of the Eleventh Judicial Circuit in and for Dade County, Florida, in Case No. 77-24730, City of Miami v. Florida East Coast Railway Company, held that "The railroad tracks presently located on the subject property are spur tracks." That is not the question before the Commission. The question before us concerns whether the entire P&O Dock terminal facility together with the railroad tracks and rights-of-way thereon, constitute a line of railroad. The State court never made that determination; it only concerned itself with the status of the track and did not address itself to the status of the P&O Dock. The quoted finding clearly delineates the limited extent of the State court decision.

Miami alleges that whether the P&O Dock is a line of railroad constitutes an "after thought of no practical significance." In addition, the argument is made that the Federal Court made a specific finding that the track is spur, and that both courts took full cognizance of the character of the entire terminal facility in reaching their decision. Such is not the case. Neither court made any finding of the type claimed by Miami.

The State court order of March 6, 1978, was a preliminary decision. Litigation is still pending and a final decision regarding the P&O Dock has yet to be issued; hence, res judicata is not applicable.

Lastly, we wish to make note of the fact that basic constitutional principles preclude the Commission from according res judicata effect to State court decisions. It has repeatedly been held that the purpose of the interstate commerce clause was to prevent the States