1
                                                                       Exhibit 1



                       SIXTH AMENDMENT TO RIGHTS AGREEMENT

         AMENDMENT, dated as of September 26, 1999 (this "Amendment"), to the
Rights Agreement, dated as of January 19, 1996, as amended as of April 5, 1996,
June 20, 1996, July 25, 1996, August 22, 1997 and June 2, 1999 (the "Rights
Agreement"), between MotivePower Industries, Inc., a Pennsylvania corporation
(successor to MotivePower Industries, Inc., a Delaware corporation) (the
"Company"), and ChaseMellon Shareholder Services, L.L.C., a New Jersey limited
liability company (formerly known as Chemical Mellon Shareholder Services,
L.L.C.) (the "Rights Agent").

         WHEREAS, the Company and Westinghouse Air Brake Company, a Delaware
corporation ("Westinghouse"), have proposed to enter into an Amended and
Restated Agreement and Plan of Merger (the "Merger Agreement") pursuant to
which, among other things, the Company will merge with and into Westinghouse
(the "Westinghouse Merger") and each outstanding share of Common Stock, par
value $0.01 per share, of the Company will be converted into .66 shares of
Common Stock of Westinghouse;

         WHEREAS, the Company and the Rights Agent desire to (i) amend the
Rights Agreement to provide that Westinghouse shall not be deemed an Acquiring
Person and no Distribution Date (as such terms are defined in the Rights
Agreement) shall be deemed to occur as a result of the execution of the Merger
Agreement, the execution of the Amended and Restated WABCO Stock Option
Agreement, dated as of September 26, 1999, between Westinghouse and the Company
or consummation of the transactions contemplated thereby, and (ii) provide that
Westinghouse Air Brake Company Employee Ownership Trust shall not constitute an
Acquiring Person after consummation of the Westinghouse Merger;

         WHEREAS, the Company and the Rights Agent desire to make certain
additional administrative changes to the Rights Agreement; and

         WHEREAS, pursuant to and in compliance with Section 27 of the Rights
Agreement, the Company and the Rights Agent desire to amend the Rights Agreement
as set forth in this Amendment.

         NOW THEREFORE, in consideration of the premises and the mutual
agreements set forth herein and in the Rights Agreement, the parties hereto
agree as follows:

         1. Section 3(d) of the Rights Agreement is hereby amended and restated
in its entirety to read as follows:

          "(d) Notwithstanding anything in this Agreement that might otherwise
     be deemed to the contrary, Westinghouse Air Brake Company shall not be
     deemed an Acquiring Person and no Distribution Date shall be deemed to
     occur, in either case, as a result of the execution and delivery of the
     agreements between the Company and Westinghouse Air Brake Company entitled
     "Agreement and Plan of Merger" and "MotivePower Stock Option Agreement" and
     dated as of June 2, 1999 or entitled


   2



     "Amended and Restated Agreement and Plan of Merger" and "Amended and
     Restated MotivePower Stock Option Agreement" and dated as of September 26,
     1999, or as a result of the consummation of the transactions contemplated
     by any of the foregoing agreements."

         2. This Amendment shall be governed by and construed in accordance with
the laws of the Commonwealth of Pennsylvania.

         3. This Amendment may be executed in counterparts and each of such
counterparts shall for all purposes be deemed to be an original, and both such
counterparts shall together constitute but one and the same instrument.

         4. Except as expressly set forth herein, this Amendment shall not by
implication or otherwise alter, modify, amend or in any way affect any of the
terms, conditions, obligations, covenants or agreements contained in the Rights
Agreement, all of which are ratified and affirmed in all respects and shall
continue in full force and effect.


   3


         IN WITNESS WHEREOF, the parties hereto have caused this Amendment to be
duly executed and attested, all as of the day and year first above written.


                                       MOTIVEPOWER INDUSTRIES, INC.


                                       By: /s/ JOHN C. POPE
                                           --------------------------------
                                           Name:  John C. Pope
                                           Title: Chairman of the Board


                                       CHASEMELLON SHAREHOLDER SERVICES,
                                       L.L.C., as Rights Agent


                                       By: /s/ LAWRENCE J. SCHWEIGER JR.
                                           --------------------------------
                                           Name:  Lawrence J. Schweiger Jr.
                                           Title: Assistant Vice President