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

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

                                  SCHEDULE 13D
                                 (Rule 13d-102)

             INFORMATION TO BE INCLUDED IN STATEMENTS FILED PURSUANT
            TO RULE 13d-1(a) AND AMENDMENTS THERETO FILED PURSUANT TO
                                  RULE 13d-2(a)

                    Under the Securities Exchange Act of 1934
                            (Amendment No. ________)*

                              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 2300


                                 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)

                                 August 6, 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 9 Pages)







--------------------------------------------------------------------------------
CUSIP NO. 89346D107              SCHEDULE 13D                PAGE 2 OF 9 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                     12,090,500
  OWNED BY            -------------------------------------------------------
    EACH                   9     SOLE DISPOSITIVE POWER
 REPORTING
PERSON WITH                      -0-
                      -------------------------------------------------------
                           10    SHARED DISPOSITIVE POWER

                                 12,090,500
-----------------------------------------------------------------------------
    11      AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

               6.1%
-----------------------------------------------------------------------------
    12      CHECK IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES
            CERTAIN SHARES*
                                                                        [ ]
-----------------------------------------------------------------------------
    13      PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

               6.1%
-----------------------------------------------------------------------------
    14      TYPE OF REPORTING PERSON*

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







--------------------------------------------------------------------------------
CUSIP NO.   89346D107            SCHEDULE 13D                PAGE 3  OF 9 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                     12,090,500
  OWNED BY            -------------------------------------------------------
    EACH                  9      SOLE DISPOSITIVE POWER
 REPORTING
PERSON WITH                      -0-
                      -------------------------------------------------------
                          10     SHARED DISPOSITIVE POWER

                                 12,090,500
-----------------------------------------------------------------------------
    11      AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

               6.1%
-----------------------------------------------------------------------------
    12      CHECK IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES
            CERTAIN SHARES*
                                                                        [ ]
-----------------------------------------------------------------------------
    13      PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

               6.1%
-----------------------------------------------------------------------------
    14      TYPE OF REPORTING PERSON*

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







--------------------------------------------------------------------------------
CUSIP NO.   89346D107            SCHEDULE 13D                PAGE 4 OF 9 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                     12,090,500
  OWNED BY            -------------------------------------------------------
    EACH                  9      SOLE DISPOSITIVE POWER
 REPORTING
PERSON WITH                      -0-
                      -------------------------------------------------------
                          10     SHARED DISPOSITIVE POWER

                                 12,090,500
-----------------------------------------------------------------------------
    11      AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

               6.1%
-----------------------------------------------------------------------------
    12      CHECK IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES
            CERTAIN SHARES*
                                                                        [ ]
-----------------------------------------------------------------------------
    13      PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

               6.1%
-----------------------------------------------------------------------------
    14      TYPE OF REPORTING PERSON*

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






--------------------------------------------------------------------------------
CUSIP NO.   89346D107            SCHEDULE 13D                PAGE 5 OF 9 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                     12,090,500
  OWNED BY            -------------------------------------------------------
    EACH                  9      SOLE DISPOSITIVE POWER
 REPORTING
PERSON WITH                      -0-
                      -------------------------------------------------------
                          10     SHARED DISPOSITIVE POWER

                                 12,090,500
-----------------------------------------------------------------------------
    11      AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

               6.1%
-----------------------------------------------------------------------------
    12      CHECK IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES
            CERTAIN SHARES*
                                                                        [ ]
-----------------------------------------------------------------------------
    13      PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

               6.1%
-----------------------------------------------------------------------------
    14      TYPE OF REPORTING PERSON*

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




--------------------------------------------------------------------------------
CUSIP NO.   89346D107            SCHEDULE 13D                PAGE  6 OF 9 Pages
--------------------------------------------------------------------------------

ITEM 1.           SECURITY AND ISSUER

          This Schedule 13D relates to the shares of Common Stock (the "Shares")
of TransAlta  Corporation (the "Issuer").  The principal executive office of the
Issuer is located at 110-12th  Avenue  S.W.,  Box 1900,  Station  "M",  Calgary,
Alberta, T2P 2M1, Canada.

ITEM 2.           IDENTITY AND BACKGROUND

          (a)  This statement is being filed by:

               (i)  The  Children's  Investment  Fund  Management  (UK) LLP,  an
English limited liability partnership ("TCIF UK");

               (ii) The Children's  Investment Fund Management  (Cayman) Ltd., a
Cayman Islands exempted company ("TCIF");

               (iii) The  Children's  Investment  Master Fund, a Cayman  Islands
exempted company (the "TCI Fund"); and

               (iv) Christopher  Hohn  (collectively  with TCIF UK, TCIF and the
TCI Fund, the "Reporting Persons").

          (b)  The address of the principal  business and  principal  office for
each of the Reporting Persons is:

               (i)  TCIF UK: 7 Clifford Street, London, W1S 2WE, United Kingdom;

               (ii) TCIF:  PO Box 309GT,  Ugland  House,  South  Church  Street,
George Town, Grand Cayman, Cayman Islands, British West Indies;

               (iii) The TCI Fund:  PO Box 309GT,  Ugland  House,  South  Church
Street, George Town, Grand Cayman, Cayman Islands, British West Indies; and

               (iv) Mr.  Hohn:  7  Clifford  Street,  London,  W1S  2WE,  United
Kingdom.

          (c)  The principal  business of both TCIF and TCIF UK is investing for
funds and accounts under its management. The TCI Fund falls under the management
of both TCIF and TCIF UK. The principal business of the TCI Fund is to invest in
securities.  Christopher  Hohn is the  Managing  Partner of TCIF UK and the 100%
owner of TCIF.

          (d)  None of the Reporting  Persons nor any of the individuals set
forth in Appendix B attached hereto has,  during the last five years,  been
convicted in a criminal proceeding (excluding traffic violations or similar
misdemeanors).

          (e)  On  June  11,  2008,  in the  case  of  CSX  CORPORATION  V.  THE
CHILDREN'S  INVESTMENT  FUND  MANAGEMENT  (UK) LLP,  ET AL in the United  States
District Court for the Southern District of New York, the Reporting Persons were
found to have  violated  Section 13 (d) of the  Securities  Exchange Act of 1934
(the  "Exchange  Act") for failing (i) to file a Schedule  13D within 10 days of
becoming,  or being deemed to have become, a beneficial owner of more that 5% of
the stock of CSX  Corporation by virtue of their  participation  in Total Return
Swaps  referencing  stock of CSX  Corporation,  and (ii) to timely disclose that
they were participants in a group with respect to stock of CSX Corporation.  The
Reporting  Persons were permanently  enjoined from future  violations of Section
13(d) of the Exchange Act and Regulation 13D thereunder.  The Reporting  Persons
are currently appealing this decision.




--------------------------------------------------------------------------------
CUSIP NO.  89346D107             SCHEDULE 13D                PAGE 7  OF 9 Pages
--------------------------------------------------------------------------------


          (f)  Christopher Hohn is a citizen of the United Kingdom.

ITEM 3.        SOURCE AND AMOUNT OF FUNDS OR OTHER CONSIDERATION

          A total of approximately $374,419,919.72, including commissions (using
an  exchange  rate of US $1.00 = Cdn  $1.0645,  the  exchange  rate in effect on
August  14,  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 4.        PURPOSE OF TRANSACTION

         The  Reporting  Persons  acquired  the  Shares  for  investment  in the
ordinary  course  of  business  because  they  believed  that the  Shares,  when
purchased,   were   undervalued   and   represented  an  attractive   investment
opportunity.

         The Reporting  Persons sent William D.  Anderson,  Chair of the Special
Committee  of the Issuer (the  "Special  Committee"),  a letter on July 29, 2008
(the "TCI  Letter")  stating  that the  Reporting  Persons  believed  a proposal
publicly  disclosed  by LS  Power  Equity  Partners  and  Global  Infrastructure
Partners  on July  21,  2008  to  acquire  the  Issuer  for  Cdn  $39 per  share
significantly  undervalued  the Issuer  and  urging  the  Issuer to  immediately
undertake an expeditious  review of strategic  alternatives and to take steps to
maximize  shareholder  value.  The TCI Letter  additionally  indicated  that the
Reporting  Persons would welcome an open dialogue with the Special  Committee as
it reviews its strategic  alternatives.  The TCI Letter is attached as Exhibit 2
to this Schedule 13D and is incorporated herein by reference.

          Except as set forth herein, the Reporting Persons have no present plan
or  proposal  that would  relate to or result in any of the matters set forth in
subparagraphs (a)-(j) of Item 4 of Schedule 13D. The Reporting Persons intend to
review their  investments in the Issuer on a continuing  basis and may engage in
discussions with  management,  the Board,  other  stockholders of the Issuer and
other  relevant  parties  concerning  the  business,   operations,   governance,
management,  strategy  and  future  plans of the  Issuer.  Depending  on various
factors  including,  without  limitation,  the Issuer's  financial  position and
strategic  direction,  the outcome of the discussions  referenced above, actions
taken by the Board, price levels of the Shares,  other investment  opportunities
available to the  Reporting  Persons,  conditions in the  securities  market and
general  economic  and industry  conditions,  the  Reporting  Persons may in the
future take such actions with respect to their investments in the Issuer as they
deem appropriate including, without limitation,  purchasing additional Shares or
selling  some or all of the Shares held by the  Reporting  Persons,  engaging in
short  selling of or any  hedging or similar  transactions  with  respect to the
Shares and/or  otherwise  changing  their  intention with respect to any and all
matters referred to in Item 4 of Schedule 13D.

ITEM 5.        INTEREST IN SECURITIES OF THE ISSUER





--------------------------------------------------------------------------------
CUSIP NO.  89346D107             SCHEDULE 13D                PAGE 8  OF 9 Pages
--------------------------------------------------------------------------------

          (a) As of the close of  business  on August 14,  2008,  the  Reporting
Persons  beneficially  owned an aggregate  of  12,090,500  Shares,  constituting
approximately 6.1% 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.

          (d)  No person other than the  Reporting  Persons is known to have the
right to receive or the power to direct the receipt of  dividends  from,  or the
proceeds from the sale of, the Shares.

          (e)  Not applicable.

ITEM 6.        CONTRACTS, ARRANGEMENTS, UNDERSTANDINGS OR RELATIONSHIPS
               WITH RESPECT TO SECURITIES OF THE ISSUER

         Except as set forth herein,  there are no contracts,  understandings or
relationships  among the persons named in Item 2 or between such persons and any
other person with respect to the Shares.

ITEM 7.        MATERIAL TO BE FILED AS EXHIBITS

Exhibit 1.  Joint Filing Agreement

Exhibit 2.  TCI Letter dated July 29, 2009






--------------------------------------------------------------------------------
CUSIP NO.  89346D107             SCHEDULE 13D                PAGE 9  OF 9 Pages
--------------------------------------------------------------------------------

                                   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:  August 15, 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






                                  EXHIBIT INDEX

Exhibit 1.  Joint Filing Agreement

Exhibit 2.  TCI Letter dated July 29, 2009




                                   APPENDIX A

                   TRANSACTIONS IN THE SHARES EFFECTED BY THE
                  REPORTING PERSONS DURING THE PAST SIXTY DAYS
           (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)

  8-Jul-08                  250,000                        $32.32
  9-Jul-08                  193,800                         32.59
 15-Jul-08                  200,000                         31.89
 16-Jul-08                  245,000                         31.22
 17-Jul-08                  200,000                         30.90
 18-Jul-08                  240,700                         32.12
 24-Jul-08                  570,000                         35.24
 25-Jul-08                  950,000                         34.30
 28-Jul-08                   92,300                         34.48
 29-Jul-08                  262,500                         34.41
 30-Jul-08                  205,300                         35.25
 31-Jul-08                   88,100                         34.85
  1-Aug-08                    4,400                         35.39
  5-Aug-08                  292,000                         34.26
  6-Aug-08                  485,000                         34.94
  7-Aug-08                  326,100                         34.56
  8-Aug-08                  338,900                         33.62
 11-Aug-08                  191,300                         33.23
 12-Aug-08                  500,000                         33.07
 13-Aug-08                  585,400                         32.84
 14-Aug-08                   41,400                         33.24

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





                                   APPENDIX B

             DIRECTORS AND EXECUTIVE OFFICERS OF REPORTING PERSONS

The following sets forth the name, position, and principal occupation of each
director and executive officer of The Children's Investment Master Fund and The
Children's Investment Fund Management (Cayman) Ltd. Except as otherwise
indicated, the business address of each director and officer is PO Box 309GT,
Ugland House, South Church Street, George Town, Grand Cayman, Cayman Islands,
British West Indies. To the best of the Reporting Persons' knowledge, except as
set forth in this Schedule 13D, none of the directors or executive officers of
either The Children's Investment Master Fund or The Children's Investment Fund
Management (Cayman) Ltd. owns any Shares.




                                                                                 
The Children's Investment Master Fund

Name                            Position                  Principal Occupation            Citizenship
Christopher Hohn                Director                  Investment Manager              United Kingdom
David DeRosa                    Director                  Financial Economist             United States
Linburgh Martin                 Director                  Accountant                      Cayman Islands

The Children's Investment Fund Management (Cayman) Ltd.

Name                            Position                  Principal Occupation            Citizenship
John Sutlic                     Director                  Accountant                      Canada
David DeRosa                    Director                  Financial Economist             United States
Linburgh Martin                 Director                  Accountant                      Cayman Islands