UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

                                  -------------

                                  SCHEDULE 13D

                    UNDER THE SECURITIES EXCHANGE ACT OF 1934
                               (AMENDMENT NO. 1)*

                              TransAlta Corporation
--------------------------------------------------------------------------------
                                (Name of Issuer)

                                  Common Stock
--------------------------------------------------------------------------------
                         (Title of Class of Securities)

                                    89346D107
--------------------------------------------------------------------------------
                                 (CUSIP Number)


                              Mr. Christopher Hohn
                            The Children's Investment
                            Fund Management (UK) LLP
                                7 Clifford Street
                                 London W1S 2WE
                                 United Kingdom
                                +44 20 7440 2330


                                 With a copy to:

                              Marc Weingarten, Esq.
                            Schulte Roth & Zabel LLP
                                919 Third Avenue
                            New York, New York 10022
                                 (212) 756-2000


--------------------------------------------------------------------------------
                  (Name, Address and Telephone Number of Person
                Authorized to Receive Notices and Communications)

                         (Continued on following pages)

                                September 8, 2008
--------------------------------------------------------------------------------
             (Date of Event which Requires Filing of This Statement)

If the filing person has previously filed a statement on Schedule 13G to report
the acquisition that is the subject of this Schedule 13D, and is filing this
schedule because of Rule 13d-1(e), 13d-1(f) or 13d-1(g), check the following
box. [ ]

NOTE: Schedules filed in paper format shall include a signed original and five
copies of the schedule, including all exhibits. See Rule 13d-7 for other parties
to whom copies are to be sent.

--------------------------
* The remainder of this cover page shall be filled out for a reporting person's
initial filing on this form with respect to the subject class of securities, and
for any subsequent amendment containing information which would alter
disclosures provided in a prior cover page. The information required on the
remainder of this cover page shall not be deemed to be "filed" for the purpose
of Section 18 of the Securities Exchange Act of 1934 ("Act") or otherwise
subject to the liabilities of that section of the Act but shall be subject to
all other provisions of the Act (however, see the Notes).

                               (Page 1 of 8 Pages)




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CUSIP NO.      89346D107            SCHEDULE 13D           PAGE 2 OF 8 Pages
--------------------------------------------------------------------------------

--------------------------------------------------------------------------------
    1       NAME OF REPORTING PERSON
            I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY)
            The Children's Investment Fund Management (UK) LLP
--------------------------------------------------------------------------------
    2       CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*       (a) [ ]
                                                                    (b) [ ]
--------------------------------------------------------------------------------
    3       SEC USE ONLY

--------------------------------------------------------------------------------
    4       SOURCE OF FUNDS*

            AF
--------------------------------------------------------------------------------
    5       CHECK IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO
            ITEMS 2(d) or 2(e)                                          [X]

--------------------------------------------------------------------------------
    6       CITIZENSHIP OR PLACE OF ORGANIZATION

            England
--------------------------------------------------------------------------------
    7       SOLE VOTING POWER

                                  -0-
--------------------------------------------------------------------------------
 NUMBER OF                 8      SHARED VOTING POWER
  SHARES
BENEFICIALLY                      14,117,400
  OWNED BY            ----------------------------------------------------------
    EACH                   9      SOLE DISPOSITIVE POWER
 REPORTING
PERSON WITH                       -0-
                      ----------------------------------------------------------
                           10     SHARED DISPOSITIVE POWER

                                  14,117,400
--------------------------------------------------------------------------------
    11      AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

            7.1%
--------------------------------------------------------------------------------
    12      CHECK IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES
            CERTAIN SHARES*
                                                                        [ ]
--------------------------------------------------------------------------------
    13      PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

            7.1%
--------------------------------------------------------------------------------
    14      TYPE OF REPORTING PERSON*

            PN
--------------------------------------------------------------------------------





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CUSIP NO.      89346D107            SCHEDULE 13D           PAGE 3 OF 8 Pages
--------------------------------------------------------------------------------

--------------------------------------------------------------------------------
    1       NAME OF REPORTING PERSON
            I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY)
            The Children's Investment Fund Management (Cayman) Ltd.
--------------------------------------------------------------------------------
    2       CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*       (a) [ ]
                                                                    (b) [ ]
--------------------------------------------------------------------------------
    3       SEC USE ONLY

--------------------------------------------------------------------------------
    4       SOURCE OF FUNDS*

            AF
--------------------------------------------------------------------------------
    5       CHECK IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO
            ITEMS 2(d) or 2(e)                                          [X]

--------------------------------------------------------------------------------
    6       CITIZENSHIP OR PLACE OF ORGANIZATION

            Cayman Islands
--------------------------------------------------------------------------------
    7       SOLE VOTING POWER

                                  -0-
--------------------------------------------------------------------------------
 NUMBER OF                 8      SHARED VOTING POWER
  SHARES
BENEFICIALLY                      14,117,400
  OWNED BY            ----------------------------------------------------------
    EACH                   9      SOLE DISPOSITIVE POWER
 REPORTING
PERSON WITH                       -0-
                      ----------------------------------------------------------
                           10     SHARED DISPOSITIVE POWER

                                  14,117,400
--------------------------------------------------------------------------------
    11      AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

            7.1%
--------------------------------------------------------------------------------
    12      CHECK IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES
            CERTAIN SHARES*
                                                                        [ ]
--------------------------------------------------------------------------------
    13      PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

            7.1%
--------------------------------------------------------------------------------
    14      TYPE OF REPORTING PERSON*

            CO
--------------------------------------------------------------------------------





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CUSIP NO.      89346D107            SCHEDULE 13D           PAGE 4 OF 8 Pages
--------------------------------------------------------------------------------

--------------------------------------------------------------------------------
    1       NAME OF REPORTING PERSON
            I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY)
            The Children's Investment Master Fund
--------------------------------------------------------------------------------
    2       CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*       (a) [ ]
                                                                    (b) [ ]
--------------------------------------------------------------------------------
    3       SEC USE ONLY

--------------------------------------------------------------------------------
    4       SOURCE OF FUNDS*

            WC
--------------------------------------------------------------------------------
    5       CHECK IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO
            ITEMS 2(d) or 2(e)                                          [X]

--------------------------------------------------------------------------------
    6       CITIZENSHIP OR PLACE OF ORGANIZATION

            Cayman Islands
--------------------------------------------------------------------------------
    7       SOLE VOTING POWER

                                  -0-
--------------------------------------------------------------------------------
 NUMBER OF                 8      SHARED VOTING POWER
  SHARES
BENEFICIALLY                      14,117,400
  OWNED BY            ----------------------------------------------------------
    EACH                   9      SOLE DISPOSITIVE POWER
 REPORTING
PERSON WITH                       -0-
                      ----------------------------------------------------------
                           10     SHARED DISPOSITIVE POWER

                                  14,117,400
--------------------------------------------------------------------------------
    11      AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

            7.1%
--------------------------------------------------------------------------------
    12      CHECK IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES
            CERTAIN SHARES*
                                                                        [ ]
--------------------------------------------------------------------------------
    13      PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

            7.1%
--------------------------------------------------------------------------------
    14      TYPE OF REPORTING PERSON*

            CO
--------------------------------------------------------------------------------





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CUSIP NO.      89346D107            SCHEDULE 13D           PAGE 5 OF 8 Pages
--------------------------------------------------------------------------------

--------------------------------------------------------------------------------
    1       NAME OF REPORTING PERSON
            I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY)
            Christopher Hohn
--------------------------------------------------------------------------------
    2       CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*       (a) [ ]
                                                                    (b) [ ]
--------------------------------------------------------------------------------
    3       SEC USE ONLY

--------------------------------------------------------------------------------
    4       SOURCE OF FUNDS*

            AF
--------------------------------------------------------------------------------
    5       CHECK IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO
            ITEMS 2(d) or 2(e)                                          [X]

--------------------------------------------------------------------------------
    6       CITIZENSHIP OR PLACE OF ORGANIZATION

            United Kingdom
--------------------------------------------------------------------------------
    7       SOLE VOTING POWER

                                  -0-
--------------------------------------------------------------------------------
 NUMBER OF                 8      SHARED VOTING POWER
  SHARES
BENEFICIALLY                      14,117,400
  OWNED BY            ----------------------------------------------------------
    EACH                   9      SOLE DISPOSITIVE POWER
 REPORTING
PERSON WITH                       -0-
                      ----------------------------------------------------------
                           10     SHARED DISPOSITIVE POWER

                                  14,117,400
--------------------------------------------------------------------------------
    11      AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

            7.1%
--------------------------------------------------------------------------------
    12      CHECK IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES
            CERTAIN SHARES*
                                                                        [ ]
--------------------------------------------------------------------------------
    13      PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

            7.1%
--------------------------------------------------------------------------------
    14      TYPE OF REPORTING PERSON*

            IN
--------------------------------------------------------------------------------





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CUSIP NO.      89346D107            SCHEDULE 13D           PAGE 6 OF 8 Pages
--------------------------------------------------------------------------------


The Schedule 13D filed on August 15, 2008 (the "Schedule 13D") by The Children's
Investment Fund Management (UK) LLP, an English limited liability partnership,
The Children's Investment Fund Management (Cayman) Ltd., a Cayman Islands
exempted company, The Children's Investment Master Fund, a Cayman Islands
exempted company, and Christopher Hohn (together, the "Reporting Persons")
relating to the shares ("Shares") of common stock of TransAlta Corporation (the
"Issuer"), is hereby amended as set forth below by this Amendment No. 1 to the
Schedule 13D.


ITEM 3.           SOURCE AND AMOUNT OF FUNDS OR OTHER CONSIDERATION

Item 3 of the Schedule 13D is hereby amended and restated as follows:

        A total of approximately $439,399,739.99, including commissions (using
an exchange rate of US $1.00 = Cdn $1.0698, the exchange rate in effect on
September 8, 2008, according to Bloomberg), was paid to acquire the Shares
reported herein. The source of funds used to acquire such Shares was the general
working capital of the TCI Fund.

ITEM 5.           INTEREST IN SECURITIES OF THE ISSUER

Paragraphs (a), (b), and (c) of Item 5 of the Schedule 13D are hereby amended
and restated as follows:

        (a) As of the close of business on September 8, 2008, the Reporting
Persons beneficially owned an aggregate of 14,117,400 Shares, constituting
approximately 7.1% of the Shares outstanding.

        The aggregate percentage of Shares beneficially owned by the Reporting
Persons is based upon 197,600,000 Shares outstanding, which is the total number
of Shares issued and outstanding as of June 30, 2008 as reported in the Issuer's
Form 6-K filed on August 4, 2008.

        (b) Each of the Reporting Persons share power to vote and direct the
disposition of the Shares held by the TCI Fund.

        (c) Information concerning transactions in the Shares effected by the
Reporting Persons during the past sixty days is set forth in Appendix A hereto
and is incorporated herein by reference.






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CUSIP NO.      89346D107            SCHEDULE 13D           PAGE 7 OF 8 Pages
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                                   SIGNATURES

        After reasonable inquiry and to the best of my knowledge and belief, I
certify that the information set forth in this statement is true, complete and
correct.

Dated:  September 10, 2008


                                          THE CHILDREN'S INVESTMENT FUND
                                          MANAGEMENT (UK) LLP


                                          /s/ Christopher Hohn
                                          ------------------------------
                                          Christopher Hohn
                                          Managing Partner



                                          THE CHILDREN'S INVESTMENT FUND
                                          MANAGEMENT (CAYMAN) LTD.


                                          /s/ David DeRosa
                                          ------------------------------
                                          David DeRosa
                                          Director



                                          THE CHILDREN'S INVESTMENT MASTER
                                          FUND


                                          /s/ David DeRosa
                                          ------------------------------
                                          David DeRosa
                                          Director


                                          /s/ Christopher Hohn
                                          ------------------------------
                                          Christopher Hohn









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CUSIP NO.      89346D107            SCHEDULE 13D           PAGE 8 OF 8 Pages
--------------------------------------------------------------------------------


                                   APPENDIX A

                   TRANSACTIONS IN THE SHARES EFFECTED BY THE
             REPORTING PERSONS SINCE THE FILING OF THE SCHEDULE 13D
           (UNLESS OTHERWISE STATED, ALL TRANSACTIONS WERE EFFECTED IN
                                THE OPEN MARKET)


The Children's Investment Master Fund


Date of Trade            Shares Purchased (Sold)            Price per Share(1)
  15-Aug-08                      342,300                         33.216
  18-Aug-08                       12,900                         33.824
  20-Aug-08                       14,300                         33.835
  21-Aug-08                          200                         34.450
  02-Sep-08                      175,200                         33.477
  03-Sep-08                    1,123,800                         33.479
  05-Sep-08                      200,000                         31.513
  08-Sep-08                      158,200                         31.962


























----------------
(1) US dollar amounts calculated using exchange rates in effect on the date of
    trade.