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. ________)*

                                 CSX Corporation
-------------------------------------------------------------------------------
                                (Name of Issuer)

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

                                    126408103
-------------------------------------------------------------------------------
                                 (CUSIP Number)


        Mr. Christopher Hohn            Mr. Alexandre Behring
        The Children's Investment       3G Capital Partners Ltd.
        Fund Management (UK) LLP        c/o 3G Capital Inc.
        7 Clifford Street               800 Third Avenue
        London W1S 2WE                  31st Floor
        United Kingdom                  New York, New York 10022
        +44 20 7440 2330                (212) 893-6727


                                 With a copy to:

        Marc Weingarten, Esq.           Stephen Fraidin, Esq.
        David Rosewater, Esq.           Andrew E. Nagel, Esq.
        Schulte Roth & Zabel LLP        Kirkland & Ellis LLP
        919 Third Avenue                153 East 53rd Street
        New York, New York 10022        New York, New York 10022
        (212) 756-2000                 (212) 446-4800



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

                         (Continued on following pages)

                                December 12, 2007
 ------------------------------------------------------------------------------
             (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 20 PAGES)






-------------------------------------------------------------------------------
CUSIP NO.      126408103            SCHEDULE 13D           PAGE 2 OF 20 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) [X]
                                                                    (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)                                         [ ]

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

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

                                  -0-
-----------------------------------------------------------------------------
 NUMBER OF                 8      SHARED VOTING POWER
  SHARES
BENEFICIALLY                      17,796,998
  OWNED BY            -------------------------------------------------------
    EACH                   9      SOLE DISPOSITIVE POWER
 REPORTING
PERSON WITH                       -0-
                      -------------------------------------------------------
                           10     SHARED DISPOSITIVE POWER

                                  17,796,998
-----------------------------------------------------------------------------
    11      AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

            4.2%
-----------------------------------------------------------------------------
    12      CHECK IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES
            CERTAIN SHARES*
                                                                        [X]
-----------------------------------------------------------------------------
    13      PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

            4.2%
-----------------------------------------------------------------------------
    14      TYPE OF REPORTING PERSON*

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






-------------------------------------------------------------------------------
CUSIP NO.      126408103            SCHEDULE 13D           PAGE 3 OF 20 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) [X]
                                                                    (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)                                         [ ]

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

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

                                  -0-
-----------------------------------------------------------------------------
NUMBER OF                 8       SHARED VOTING POWER
  SHARES
BENEFICIALLY                      17,796,998
  OWNED BY            -------------------------------------------------------
    EACH                   9      SOLE DISPOSITIVE POWER
 REPORTING
PERSON WITH                       -0-
                      -------------------------------------------------------
                           10     SHARED DISPOSITIVE POWER

                                  17,796,998
-----------------------------------------------------------------------------
    11      AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

            4.2%
-----------------------------------------------------------------------------
    12      CHECK IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES
            CERTAIN SHARES*
                                                                        [X]
-----------------------------------------------------------------------------
    13      PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

            4.2%
-----------------------------------------------------------------------------
    14      TYPE OF REPORTING PERSON*

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






-------------------------------------------------------------------------------
CUSIP NO.      126408103            SCHEDULE 13D           PAGE 4 OF 20 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) [X]
                                                                    (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)                                         [ ]

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

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

                                  -0-
-----------------------------------------------------------------------------
NUMBER OF                 8       SHARED VOTING POWER
  SHARES
BENEFICIALLY                      17,796,998
  OWNED BY            -------------------------------------------------------
    EACH                   9      SOLE DISPOSITIVE POWER
 REPORTING
PERSON WITH                       -0-
                      -------------------------------------------------------
                           10     SHARED DISPOSITIVE POWER

                                  17,796,998
-----------------------------------------------------------------------------
    11      AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

            4.2%
-----------------------------------------------------------------------------
    12      CHECK IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES
            CERTAIN SHARES*
                                                                        [X]
-----------------------------------------------------------------------------
    13      PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

            4.2%
-----------------------------------------------------------------------------
    14      TYPE OF REPORTING PERSON*

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





-------------------------------------------------------------------------------
CUSIP NO.      126408103            SCHEDULE 13D           PAGE 5 OF 20 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) [X]
                                                                    (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)                                         [ ]

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

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

                                  -0-
-----------------------------------------------------------------------------
NUMBER OF                 8       SHARED VOTING POWER
  SHARES
BENEFICIALLY                      17,796,998
  OWNED BY            -------------------------------------------------------
    EACH                   9      SOLE DISPOSITIVE POWER
 REPORTING
PERSON WITH                       -0-
                      -------------------------------------------------------
                           10     SHARED DISPOSITIVE POWER

                                  17,796,998
-----------------------------------------------------------------------------
    11      AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

            4.2%
-----------------------------------------------------------------------------
    12      CHECK IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES
            CERTAIN SHARES*
                                                                        [X]
-----------------------------------------------------------------------------
    13      PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

            4.2%
-----------------------------------------------------------------------------
    14      TYPE OF REPORTING PERSON*

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




-------------------------------------------------------------------------------
CUSIP NO.      126408103            SCHEDULE 13D           PAGE 6 OF 20 PAGES
-------------------------------------------------------------------------------

-------------------------------------------------------------------------------
    1       NAME OF REPORTING PERSON
            I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY)
            3G Capital Partners Ltd.
-----------------------------------------------------------------------------
    2       CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*       (a) [X]
                                                                    (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)                                         [ ]

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

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

                                  -0-
-----------------------------------------------------------------------------
NUMBER OF                 8       SHARED VOTING POWER
  SHARES
BENEFICIALLY                      17,232,854
  OWNED BY            -------------------------------------------------------
    EACH                   9      SOLE DISPOSITIVE POWER
 REPORTING
PERSON WITH                       -0-
                      -------------------------------------------------------
                           10     SHARED DISPOSITIVE POWER

                                  17,232,854
-----------------------------------------------------------------------------
    11      AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

            4.1%
-----------------------------------------------------------------------------
    12      CHECK IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES
            CERTAIN SHARES*
                                                                        [X]
-----------------------------------------------------------------------------
    13      PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

            4.1%
-----------------------------------------------------------------------------
    14      TYPE OF REPORTING PERSON*

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






-------------------------------------------------------------------------------
CUSIP NO.      126408103            SCHEDULE 13D           PAGE 7 OF 20 PAGES
-------------------------------------------------------------------------------

-------------------------------------------------------------------------------
    1       NAME OF REPORTING PERSON
            I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY)
            3G Capital Partners, L.P.
-----------------------------------------------------------------------------
    2       CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*       (a) [X]
                                                                    (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)                                         [ ]

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

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

                                  -0-
-----------------------------------------------------------------------------
NUMBER OF                 8       SHARED VOTING POWER
  SHARES
BENEFICIALLY                      17,232,854
  OWNED BY            -------------------------------------------------------
    EACH                   9      SOLE DISPOSITIVE POWER
 REPORTING
PERSON WITH                       -0-
                      -------------------------------------------------------
                           10     SHARED DISPOSITIVE POWER

                                  17,232,854
-----------------------------------------------------------------------------
    11      AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

            4.1%
-----------------------------------------------------------------------------
    12      CHECK IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES
            CERTAIN SHARES*
                                                                        [X]
-----------------------------------------------------------------------------
    13      PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

            4.1%
-----------------------------------------------------------------------------
    14      TYPE OF REPORTING PERSON*

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





-------------------------------------------------------------------------------
CUSIP NO.      126408103            SCHEDULE 13D           PAGE 8 OF 20 PAGES
-------------------------------------------------------------------------------

-------------------------------------------------------------------------------
    1       NAME OF REPORTING PERSON
            I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY)
            3G Fund L.P.
-----------------------------------------------------------------------------
    2       CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*       (a) [X]
                                                                    (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)                                         [ ]

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

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

                                  -0-
-----------------------------------------------------------------------------
NUMBER OF                 8       SHARED VOTING POWER
  SHARES
BENEFICIALLY                      17,232,854
  OWNED BY            -------------------------------------------------------
    EACH                   9      SOLE DISPOSITIVE POWER
 REPORTING
PERSON WITH                       -0-
                      -------------------------------------------------------
                           10     SHARED DISPOSITIVE POWER

                                  17,232,854
-----------------------------------------------------------------------------
    11      AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

            4.1%
-----------------------------------------------------------------------------
    12      CHECK IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES
            CERTAIN SHARES*
                                                                        [X]
-----------------------------------------------------------------------------
    13      PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

            4.1%
-----------------------------------------------------------------------------
    14      TYPE OF REPORTING PERSON*

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




-------------------------------------------------------------------------------
CUSIP NO.      126408103            SCHEDULE 13D           PAGE 9 OF 20 PAGES
-------------------------------------------------------------------------------

-------------------------------------------------------------------------------
    1       NAME OF REPORTING PERSON
            I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY)
            Alexandre Behring
-----------------------------------------------------------------------------
    2       CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*       (a) [X]
                                                                    (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)                                         [ ]

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

            Brazil
-----------------------------------------------------------------------------
    7       SOLE VOTING POWER

                                  -0-
-----------------------------------------------------------------------------
NUMBER OF                 8       SHARED VOTING POWER
  SHARES
BENEFICIALLY                      17,232,854
  OWNED BY            -------------------------------------------------------
    EACH                   9      SOLE DISPOSITIVE POWER
 REPORTING
PERSON WITH                       -0-
                      -------------------------------------------------------
                           10     SHARED DISPOSITIVE POWER

                                  17,232,854
-----------------------------------------------------------------------------
    11      AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

            4.1%
-----------------------------------------------------------------------------
    12      CHECK IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES
            CERTAIN SHARES*
                                                                        [X]
-----------------------------------------------------------------------------
    13      PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

            4.1%
-----------------------------------------------------------------------------
    14      TYPE OF REPORTING PERSON*

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




-------------------------------------------------------------------------------
CUSIP NO.      126408103            SCHEDULE 13D           PAGE 10 OF 20 PAGES
-------------------------------------------------------------------------------

-------------------------------------------------------------------------------
    1       NAME OF REPORTING PERSON
            I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY)
            Gilbert H. Lamphere
-----------------------------------------------------------------------------
    2       CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*       (a) [X]
                                                                    (b) [ ]

-----------------------------------------------------------------------------
    3       SEC USE ONLY

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

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

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

            United States
-----------------------------------------------------------------------------
    7       SOLE VOTING POWER

                                  22,600
-----------------------------------------------------------------------------
 NUMBER OF                 8      SHARED VOTING POWER
  SHARES
BENEFICIALLY                      -0-
  OWNED BY            -------------------------------------------------------
    EACH                   9      SOLE DISPOSITIVE POWER
 REPORTING
PERSON WITH                       22,600
                      -------------------------------------------------------
                           10     SHARED DISPOSITIVE POWER

                                  -0-
-----------------------------------------------------------------------------
    11      AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

            22,600
-----------------------------------------------------------------------------
    12      CHECK IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES
            CERTAIN SHARES*
                                                                        [ ]
-----------------------------------------------------------------------------
    13      PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

            0.0%
-----------------------------------------------------------------------------
    14      TYPE OF REPORTING PERSON*

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





-------------------------------------------------------------------------------
CUSIP NO.      126408103            SCHEDULE 13D           PAGE 11 OF 20 PAGES
-------------------------------------------------------------------------------

-------------------------------------------------------------------------------
    1       NAME OF REPORTING PERSON
            I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY)
            Timothy T. O'Toole
-----------------------------------------------------------------------------
    2       CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*       (a) [X]
                                                                    (b) [ ]

-----------------------------------------------------------------------------
    3       SEC USE ONLY

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

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

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

            United States
-----------------------------------------------------------------------------
    7       SOLE VOTING POWER

                                  2,500
-----------------------------------------------------------------------------
 NUMBER OF                 8      SHARED VOTING POWER
  SHARES
BENEFICIALLY                      -0-
  OWNED BY            -------------------------------------------------------
    EACH                   9      SOLE DISPOSITIVE POWER
 REPORTING
PERSON WITH                       2,500
                      -------------------------------------------------------
                           10     SHARED DISPOSITIVE POWER

                                  -0-
-----------------------------------------------------------------------------
    11      AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

            2,500
-----------------------------------------------------------------------------
    12      CHECK IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES
            CERTAIN SHARES*
                                                                        [ ]
-----------------------------------------------------------------------------
    13      PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

            0.0%
-----------------------------------------------------------------------------
    14      TYPE OF REPORTING PERSON*

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





-------------------------------------------------------------------------------
CUSIP NO.      126408103            SCHEDULE 13D           PAGE 12 OF 20 PAGES
-------------------------------------------------------------------------------

ITEM 1.     SECURITY AND ISSUER

This  Schedule  13D relates to the shares of Common  Stock,  par value $1.00 per
share (the "Shares"), of CSX Corporation (the "Issuer"). The principal executive
office of the Issuer is located at 500 Water Street,  15th Floor,  Jacksonville,
FL 32202.

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"), with respect to the Shares owned by
the TCI Fund (as defined below) (the "TCI Shares");

          (ii) The Children's Investment Fund Management (Cayman) Ltd., a Cayman
Islands exempted company ("TCIF"), with respect to the TCI Shares;

          (iii) The Children's Investment Master Fund, a Cayman Islands exempted
company (the "TCI Fund"), with respect to the Shares directly owned by it;

          (iv)  Christopher  Hohn, with respect to the TCI Shares  (collectively
with TCIF UK, TCIF and the TCI Fund, the "TCI Reporting Persons");

          (v) 3G Capital  Partners Ltd., a Cayman Islands  exempted company ("3G
Capital  Ltd."),  with  respect to the Shares  owned by the 3G Fund (as  defined
below) (the "3G Shares");

          (vi) 3G Capital Partners,  L.P., a Cayman Islands limited  partnership
("3G Capital L.P."), with respect to the 3G Shares;

          (vii) 3G Fund L.P.,  a Cayman  Islands  limited  partnership  (the "3G
Fund"), with respect to the Shares directly owned by it;

          (viii) Alexandre Behring, with respect to the 3G Shares (collectively,
with 3G  Capital  Ltd.,  3G  Capital  L.P.  and the 3G Fund,  the "3G  Reporting
Persons");

          (ix) Gilbert H. Lamphere,  with respect to the 22,600 Shares  directly
owned by him;

          (x) Timothy T.  O'Toole,  with  respect to the 2,500  Shares  directly
owned by him; and

          (xi) Gary L. Wilson (together  with Messrs. Lamphere and O'Toole,  the
"Additional  Nominees," and collectively  with Alexandre Behring and Christopher
Hohn, the "Nominees").

(b) The address of the principal  business and principal  office for each of the
TCI Reporting  Persons,  the 3G Reporting  Persons and the  Additional  Nominees
(collectively, 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;

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




--------------------------------------------------------------------------------
CUSIP NO.      126408103            SCHEDULE 13D           PAGE 13 OF 20 PAGES
--------------------------------------------------------------------------------

          (v) 3G Capital  Ltd.:  36A Dr Roy's Drive,  P.O. Box 2510 George Town,
Grand Cayman, Cayman Islands, British West Indies;

          (vi) 3G Capital L.P.:  36A Dr Roy's Drive,  P.O. Box 2510 George Town,
Grand Cayman, Cayman Islands, British West Indies;

          (vii) The 3G Fund:  36A Dr Roy's  Drive,  P.O.  Box 2510 George  Town,
Grand Cayman, Cayman Islands, British West Indies;

          (viii) Mr. Behring:  800 Third Avenue,  31st Floor, New York, New York
10022;

          (ix) Mr.  Lamphere:  645 Fifth Avenue,  18th Floor, New York, New York
10022;

          (x) Mr. O'Toole: 55 Broadway, London, SW1H OBD, United Kingdom; and

          (xi) Mr. Wilson: 300 Delfern Drive, Los Angeles, California 90077.

(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.

The principal  business of 3G Capital Ltd. is serving as the general  partner of
3G Capital  L.P.  The  principal  business of 3G Capital  L.P. is serving as the
general  partner of the 3G Fund.  The  principal  business  of the 3G Fund is to
invest in securities.  The name,  citizenship,  present principal  occupation or
employment  and business  address of each director and  executive  officer of 3G
Capital Ltd. are set forth in Appendix B attached hereto.

Alexandre Behring is the Managing Director of 3G Capital Ltd.

Gilbert H. Lamphere is the Managing Director of Lamphere Capital Management.

Timothy T. O'Toole is the Managing Director of London Underground Ltd.

Gary L. Wilson is a private investor.

(d)  None of the  Reporting  Persons,  during  the  last  five  years,  has been
convicted in a criminal  proceeding  (excluding  traffic  violations  or similar
misdemeanors).

(e) None of the Reporting Persons, during the last five years, has been party to
a  civil  proceeding  of  a  judicial  or   administrative   body  of  competent
jurisdiction and as a result of such proceeding was or is subject to a judgment,
decree  or final  order  enjoining  future  violations  of,  or  prohibiting  or
mandating activities subject to, federal or state securities laws or finding any
violation with respect to such laws.

(f) (i)  Christopher  Hohn is a citizen of the United  Kingdom,  (ii)  Alexandre
Behring is a citizen of Brazil,  (iii)  Gilbert H.  Lamphere is a citizen of the
United States, (iv) Timothy T. O'Toole is a citizen of the United States and (v)
Gary L. Wilson is a citizen of the United States.

ITEM 3.     SOURCE AND AMOUNT OF FUNDS OR OTHER CONSIDERATION

The  source of funds  used to acquire  the TCI  Shares  reported  herein was the
general working capital of the TCI Fund. The source of funds used to acquire the
3G Shares  reported  herein was the general  working capital of the 3G Fund. The
source of funds used to acquire  the Shares  reported  herein held by Gilbert H.
Lamphere  and Timothy  T. O'Toole were their  respective  personal  funds.




--------------------------------------------------------------------------------
CUSIP NO.      126408103            SCHEDULE 13D           PAGE 14 OF 20 PAGES
--------------------------------------------------------------------------------

A total of (1) $762,251,613,  including commissions, was paid to acquire the TCI
Shares;  (2)  $707,588,338,  including  commissions,  was paid to acquire the 3G
Shares;  (3)  $1,004,063,  including  commissions,  was paid to acquire  Gilbert
Lamphere's Shares and (4) $105,705,  including commissions,  was paid to acquire
Timothy O'Toole's Shares, all as reported herein.

ITEM 4.     PURPOSE OF TRANSACTION

The TCI  Reporting  Persons and the 3G  Reporting  Persons  originally  acquired
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.  Messrs. Lamphere and O'Toole acquired their Shares in
connection  with becoming  nominees to the board of directors of the Issuer (the
"Board").

After multiple  unsuccessful attempts to engage the management or the Board in a
constructive  dialogue  regarding the  operations of the Issuer,  on October 16,
2007,  the TCI Reporting  Persons  delivered a letter to the Board setting forth
numerous  failings  in  the  Issuer's   operations,   corporate  governance  and
management,  and asking the Board to take the  following  actions:  separate the
Chairman and CEO roles; refresh the Board with new independent directors;  allow
shareholders to call special shareholder meetings; align management compensation
with shareholder  interests;  justify the capital spending plan to shareholders;
and provide to shareholders a plan to improve  operations.  On October 22, 2007,
the TCI  Reporting  Persons sent a second  letter to the Board  criticizing  the
Board for  allowing  representatives  of the Issuer to describe  the Issuer as a
"public service company" in communications to policymakers in Washington, DC and
also  criticizing a statement made by the Issuer's CEO that no industry of which
he was aware analyzes returns on investment capital on a replacement cost basis.
A copy of the  October  16 and the  October 22 letters  are  attached  hereto as
Exhibits 2 and 3, respectively, and incorporated by reference herein.

The Reporting Persons currently intend to conduct a proxy  solicitation  seeking
to elect the  Nominees  to the Board at the  Issuer's  2008 Annual  Meeting.  On
December 12, 2007, the TCI  Reporting  Persons  delivered a letter to the Issuer
informing the Issuer of their intention to propose  nominees for election to the
Board at the Issuer's 2008 Annual Meeting and requesting  certain documents from
the Issuer required under the Issuer's bylaws to be completed by nominees to the
Board  in  order  to  comply  with  a  formal  notification  process  for  Board
nominations set forth in the Issuer's bylaws.

Except  as set forth  herein or as would  occur  upon  completion  of any of the
actions discussed 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.





-------------------------------------------------------------------------------
CUSIP NO.      126408103            SCHEDULE 13D           PAGE 15 OF 20 PAGES
-------------------------------------------------------------------------------

ITEM 5.     INTEREST IN SECURITIES OF THE ISSUER

     (a) As of the close of business on December  18,  2007,  the TCI  Reporting
Persons  beneficially  owned an aggregate  of  17,796,998  Shares,  constituting
approximately  4.2%  of  the  Shares  outstanding,   the  3G  Reporting  Persons
beneficially owned an aggregate of 17,232,854 Shares, constituting approximately
4.1% of the  Shares  outstanding,  Gilbert  H.  Lamphere  beneficially  owned an
aggregate  of  22,600  Shares,   constituting  less  than  0.1%  of  the  Shares
outstanding, Timothy T. O'Toole beneficially owned an aggregate of 2,500 Shares,
constituting  less than 0.1% of the Shares  outstanding  (which  such Shares are
held in an Individual Retirement Account in his name, the custodian for which is
Citigroup Global Markets Inc.) and Gary L. Wilson beneficially owned no Shares.

On December 12, 2007,  TCIF UK and 3G Capital Ltd.  entered into an agreement to
coordinate  certain of their  efforts  with regard (i) the  purchase and sale of
Shares and/or options,  swaps or other derivative securities or instruments that
constitute or may by their terms create beneficial  ownership of common stock of
the Issuer (collectively, the "Securities") held by TCIF UK, 3G Capital Ltd. and
any investment funds,  managed accounts and other investment vehicles managed or
advised by either of them,  including  the other TCI  Reporting  Persons and the
other 3G  Reporting  Persons,  and (ii) the proposal of certain  actions  and/or
transactions  to the Issuer (the  "Letter  Agreement").  The terms of the Letter
Agreement are described in Item 6 of this Schedule 13D.

By  virtue  of the  Letter  Agreement,  the  TCI  Reporting  Persons  and the 3G
Reporting  Persons may be deemed to have formed a "group," within the meaning of
Section  13(d)(3) of the  Securities  Act of 1934.  Furthermore,  the Additional
Nominees  may be deemed a part of the  aforementioned  "group"  by virtue of the
contemplated  proxy  solicitation,  their  agreement  to be  nominees  and their
ownership of Shares (as  applicable).  Collectively,  the group may be deemed to
have voting control over a combined 8.3% of the Shares. However, each of the TCI
Reporting  Persons  expressly  disclaims  beneficial  ownership  of  the  Shares
beneficially  owned by the 3G Reporting Persons and the Additional  Nominees (as
applicable),  each of the 3G Reporting  Persons expressly  disclaims  beneficial
ownership of the Shares  beneficially owned by the TCI Reporting Persons and the
applicable  Additional  Nominees  (as  applicable),  and each of the  applicable
Additional  Nominees  expressly  disclaims  beneficial  ownership  of the Shares
beneficially  owned by the TCI Reporting  Persons,  the 3G Reporting Persons and
the other Additional Nominees.

The TCI Reporting  Persons are responsible for the  completeness and accuracy of
the information  concerning the TCI Reporting Persons contained herein,  but are
not responsible for the  completeness or accuracy of the information  concerning
the 3G Reporting  Persons or any of the Additional  Nominees  contained  herein,
except to the  extent  that the TCI  Reporting  Persons  know or have  reason to
believe  that such  information  is  inaccurate.  The 3G  Reporting  Persons are
responsible for the completeness and accuracy of the information  concerning the
3G  Reporting  Persons  contained  herein,  but  are  not  responsible  for  the
completeness or accuracy of the information concerning the TCI Reporting Persons
or any of the Additional  Nominees  contained herein,  except to the extent that
the 3G Reporting Persons know or have reason to believe that such information is
inaccurate.  Each  Additional  Nominee is responsible for the  completeness  and
accuracy of the information concerning such Additional Nominee contained herein,
but is not  responsible  for the  completeness  or accuracy  of the  information
concerning the TCI Reporting Persons,  the 3G Reporting  Persons,  or any of the
other  Additional  Nominees  contained  herein,  except to the extent  that such
Additional  Nominee  knows or has reason to  believe  that such  information  is
inaccurate.


--------------------------------------------------------------------------------
CUSIP NO.      126408103            SCHEDULE 13D           PAGE 16 OF 20 PAGES
--------------------------------------------------------------------------------

The  aggregate  percentage  of Shares  beneficially  owned by the TCI  Reporting
Persons,  the 3G Reporting  Persons and the  applicable  Additional  Nominees is
based upon 420,425,477 Shares  outstanding,  which is the total number of Shares
outstanding  as of  September  28, 2007 as reported  in the  Issuer's  Quarterly
Report on Form 10-Q for the period ended September 28, 2007.

     (b)  The  TCI  Reporting  Persons  share  power  to  vote  and  direct  the
disposition  of all of the TCI Shares.  Thus,  as of December 18, 2007,  the TCI
Reporting  Persons may be deemed to beneficially own 17,796,998  Shares, or 4.2%
of the  outstanding  Shares.  The 3G Reporting  Persons  share power to vote and
direct the  disposition of all of the 3G Shares.  Thus, as of December 18, 2007,
the 3G Reporting Persons may be deemed to beneficially own 17,232,854 Shares, or
4.1%  of  the  outstanding   Shares.   Alexandre  Behring,   by  virtue  of  his
relationships to 3G Capital Ltd., 3G Capital L.P. and 3G Fund (discussed in Item
2), may be deemed to have shared voting power and shared  dispositive power with
regard  to, and  therefore  may be deemed to  beneficially  own (as that term is
defined in Rule 13d-3 under the Act), the 3G Shares. Alexandre Behring disclaims
beneficial  ownership of the 3G Shares for all other purposes.  Gilbert Lamphere
has sole power to vote and direct the  disposition  of 22,600 Shares and Timothy
O'Toole has sole power to vote and direct the disposition of 2,500 Shares.

     (c) During the past sixty days, the TCI Reporting Persons have not effected
any transactions in Shares of the Issuer. Information concerning transactions in
the Shares  effected by the 3G Reporting  Persons and the applicable  Additional
Nominees during the past sixty days is set forth in Appendix A hereto.

     (d) No person  other  than the TCI  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 TCI Shares, no person other than the 3G 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 3G Shares and no person
other than each Additional  Nominee 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,
each Additional Nominee's respective Shares (as applicable).

     (e) Not applicable.

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

On  December  12,  2007 TCIF UK and 3G  Capital  Ltd.  entered  into the  Letter
Agreement to  coordinate  certain of their  efforts with regard (i) the purchase
and sale of  Securities  held by TCIF UK, 3G  Capital  Ltd.  and any  investment
funds,  managed  accounts and other  investment  vehicles  managed or advised by
either  of them,  including  the other TCI  Reporting  Persons  and the other 3G
Reporting Persons,  and (ii) the proposal of certain actions and/or transactions
to the Issuer.  Under the Letter Agreement,  certain matters will require mutual
agreement  of TCIF UK and 3G Capital  Ltd.:  (i) whether to run a proxy  contest
involving the Issuer and the selection and nomination of individuals to serve as
directors of the Issuer for such proxy  contest (as to which matters TCIF UK and
3G Capital Ltd. have agreed),  (ii) the making,  revising or  withdrawing of any
proposals  to the  Issuer  regarding  the  conduct  of its  business,  corporate
governance matters,  corporate transactions or otherwise, (iii) the admission or
withdrawal  of any  additional  members to the group being  formed by the Letter
Agreement,  and (iv) the conduct of any litigation or  investigation if the same
relates to the group conduct of the parties.

If the parties have agreed on a matter set forth in clauses  (i),  (ii) or (iii)
above,  TCIF  UK will  assume  decision-making  authority  with  respect  to the
execution of such matter, including with respect to (i) the conduct of any proxy
contest  involving the Issuer and (ii) the manner,  form,  content and timing of
any  communications  with the Issuer as well as any public  disclosures,  public
statements  or other third  party  communications  relating  to the Issuer,  the
Securities, the Letter Agreement and the activities of the TCI Reporting Persons
and the 3G Reporting Persons pursuant thereto.




--------------------------------------------------------------------------------
CUSIP NO.      126408103            SCHEDULE 13D           PAGE 17 OF 20 PAGES
--------------------------------------------------------------------------------

The Letter Agreement provides for certain shared and separate expenses,  as well
as termination  provisions  applicable  under certain  circumstances,  which are
specified  therein.  The  foregoing  is a summary  only and this summary and any
other references  herein to the Letter Agreement are qualified in their entirety
by the Letter Agreement,  which is attached hereto as Exhibit 4 and incorporated
herein by reference.

The TCI Reporting  Persons  currently  have  contractual  agreements  with eight
credit  counterparties:  Citigroup  Global  Markets  Limited,  Deutsche Bank AG,
Goldman Sachs International,  Merrill Lynch International, UBS AG, Credit Suisse
Securities  (Europe)  Limited,  JP Morgan  Chase Bank and  Morgan  Stanley & Co.
International  plc (f/k/a  Morgan  Stanley & Co.  International  Limited),  with
regard  to  cash-settled  equity  swaps  (the "TCI  Total  Return  Swaps")  that
reference Shares of the Issuer.  The TCI Total Return Swaps constitute  economic
exposure to approximately 11% of the Shares. These contracts do not give the TCI
Reporting Persons direct or indirect voting,  investment or dispositive  control
over any securities of the Issuer and do not require the counterparties  thereto
to acquire, hold, vote or dispose of any securities of the Issuer.  Accordingly,
the TCI Reporting  Persons disclaim any beneficial  ownership in securities that
may be referenced in such contracts or that may be held from time to time by any
counterparties to the contracts.

The 3G Reporting  Persons  currently  have  contractual  agreements  with Morgan
Stanley & Co.  International  plc with regard to cash-settled  equity swaps (the
"3G Total  Return  Swaps")  that  reference  Shares of the Issuer.  The 3G Total
Return Swaps constitute  economic exposure to approximately  0.8% of the Shares.
In addition, the 3G Reporting Persons currently have contractual agreements with
Morgan  Stanley  Capital  Services Inc. with regard to credit default swaps that
reference debt  securities of the Issuer.  The contracts  regarding the 3G Total
Return  Swaps and  credit  default  swaps do not give the 3G  Reporting  Persons
direct or indirect voting, investment or dispositive control over any securities
of the Issuer and do not require the  counterparties  thereto to acquire,  hold,
vote or dispose of any securities of the Issuer.  Accordingly,  the 3G Reporting
Persons  disclaim any beneficial  ownership in securities that may be referenced
in such contracts or that may be held from time to time by any counterparties to
the contracts.

In addition to the agreements  referenced above, the Reporting Persons may, from
time to time, enter into and dispose of additional  cash-settled  equity swap or
other similar derivative  transactions with one or more  counterparties that are
based upon the value of Common Stock of the Issuer,  which  transactions  may be
significant  in  amount.  The  profit,  loss  and/or  return on such  additional
contracts  may be wholly  or  partially  dependent  on the  market  value of the
Shares,  the  relative  value  of  Shares  in  comparison  to one or more  other
financial instruments, indexes or securities, a basket or group of securities in
which the Shares may be included, or a combination of any of the foregoing.

The Reporting  Persons have entered into a Joint Filing  Agreement,  dated as of
December 18, 2007 (the "Joint  Filing  Agreement"),  a copy of which is attached
hereto as Exhibit 1. The  Reporting  Persons have filed this  statement  jointly
pursuant to the Joint Filing Agreement in view of the Letter Agreement.

Except as described herein, there are no contracts, arrangements, understandings
or  relationships  (legal or otherwise) among the persons named in Item 2 hereof
and between such persons and any person with  respect to any  securities  of the
Issuer, including but not limited to transfer or voting of any other securities,
finder's  fees,  joint  ventures,  loan or option  arrangements,  puts or calls,
guarantees  of  profits,  divisions  of  profits  or  loss,  or  the  giving  or
withholding of proxies.




--------------------------------------------------------------------------------
CUSIP NO.      126408103            SCHEDULE 13D           PAGE 18 OF 20 PAGES
--------------------------------------------------------------------------------

ITEM 7.     MATERIAL TO BE FILED AS EXHIBITS

Exhibit 1.  Joint Filing Agreement.

Exhibit 2.  Letter from TCIF UK to the CSX Board of Directors
            dated October 16, 2007

Exhibit 3.  Letter from TCIF UK to the CSX Board of Directors
            dated October 22, 2007

Exhibit 4.  Letter Agreement between TCIF UK and 3G Capital Ltd.
            dated December 12, 2007





--------------------------------------------------------------------------------
CUSIP NO.      126408103            SCHEDULE 13D           PAGE 19 OF 20 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: December 18, 2007


                                        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

                                        3G CAPITAL PARTNERS, L.P.
                                        By:  3G Capital Partners Ltd.
                                        Its: General Partner

                                        /s/ Alexandre Behring
                                        ------------------------------
                                            Alexandre Behring
                                            Managing Director

                                        3G CAPITAL PARTNERS LTD.

                                        /s/ Alexandre Behring
                                        ------------------------------
                                        Alexandre Behring
                                        Managing Director

                                        3G FUND L.P.
                                        By:  3G Capital Partners, L.P.
                                        Its: General Partner

                                        By:  3G Capital Partners Ltd.
                                        Its: General Partner

                                        /s/ Alexandre Behring
                                        ------------------------------
                                            Alexandre Behring
                                            Managing Director

                                        /s/ Alexandre Behring
                                        ------------------
                                        Alexandre Behring

                                        /s/ Gilbert H. Lamphere
                                        ------------------------------
                                        Gilbert H. Lamphere

                                        /s/ Timothy T. O'Toole
                                        ------------------------------
                                        Timothy T. O'Toole

                                        /s/ Gary L. Wilson
                                        ------------------------------
                                        Gary L. Wilson





-------------------------------------------------------------------------------
CUSIP NO.      126408103            SCHEDULE 13D           PAGE 20 OF 20 PAGES
-------------------------------------------------------------------------------


                                  EXHIBIT INDEX

Exhibit 1.  Joint Filing Agreement.

Exhibit 2.  Letter from TCIF UK to the CSX Board of Directors
            dated October 16, 2007

Exhibit 3.  Letter from TCIF UK to the CSX Board of Directors
            dated October 22, 2007

Exhibit 4.  Letter Agreement between TCIF UK and 3G Capital Ltd.
            dated December 12, 2007





                                   APPENDIX A

                TRANSACTIONS EFFECTED DURING THE PAST SIXTY DAYS

               All transactions were effected in the open market.

3G PARTIES

-------------------------------------------------------------------------------
Name                 Date of Trade       Number of Shares    Price per Share

3G Fund, L.P.           10/11/07              359,000              42.08
3G Fund, L.P.           10/11/07               63,200              42.08
3G Fund, L.P.           10/12/07              235,500              42.51
3G Fund, L.P.           10/12/07               41,600              42.51
3G Fund, L.P.           10/15/07              214,000              42.56
3G Fund, L.P.           10/15/07               37,700              42.56
3G Fund, L.P.           11/1/07                68,000              43.57
3G Fund, L.P.           11/1/07               358,100              43.84
3G Fund, L.P.           11/1/07                63,200              43.84
3G Fund, L.P.           11/1/07                12,000              43.57
3G Fund, L.P.           11/2/07               425,000              43.33
3G Fund, L.P.           11/2/07                75,000              43.33
3G Fund, L.P.           11/5/07               255,000              43.84
3G Fund, L.P.           11/5/07                45,000              43.84
3G Fund, L.P.           11/7/07               510,000              43.94
3G Fund, L.P.           11/7/07                90,000              43.94
3G Fund, L.P.           11/8/07                85,000              43.94
3G Fund, L.P.           11/8/07                15,000              43.94
-------------------------------------------------------------------------------


ADDITIONAL NOMINEES

-------------------------------------------------------------------------------
Name                 Date of Trade       Number of Shares    Price per Share

Gilbert H. Lamphere     11/6/07                18,000               44.81
Gilbert H. Lamphere     11/13/07                4,600               42.92
-------------------------------------------------------------------------------


-------------------------------------------------------------------------------
Name                 Date of Trade       Number of Shares    Price per Share

Timothy T. O'Toole      12/6/07                2,500               42.30






                                   APPENDIX B

            DIRECTORS AND EXECUTIVE OFFICERS OF THE REPORTING PERSONS

The following sets forth the name,  position,  and principal  occupation of each
director and  executive  officer of 3G Capital Ltd.  Each such  individual  is a
citizen of Brazil.  Except as otherwise indicated,  the business address of each
director and officer is 800 Third Avenue,  31st Floor, New York, New York 10022.
To the best of the 3G Reporting Persons' knowledge,  except as set forth in this
Schedule  13D,  none of the  directors or executive  officers of 3G Capital Ltd.
owns any Shares.

Name                   Position             Principal Occupation
Alexandre Behring      Managing Director    Managing Director of 3G Capital Ltd.
Alexandre Perez        Director             Director of 3G Capital Ltd.
Luis Henrique Moura    Director             Director of 3G Capital Ltd.






                                    EXHIBIT 1
                             JOINT FILING AGREEMENT

The undersigned  acknowledge and agree that the foregoing  statement on Schedule
13D is filed  on  behalf  of each of the  undersigned  and  that all  subsequent
amendments  to this  statement on Schedule 13D may be filed on behalf of each of
the  undersigned  without  the  necessity  of  filing  additional  joint  filing
agreements.  The undersigned  acknowledge that each shall be responsible for the
timely filing of such  amendments,  and for the completeness and accuracy of the
information  concerning him or it contained herein and therein, but shall not be
responsible for the completeness and accuracy of the information  concerning the
others,  except to the extent that he or it knows or has reason to believe  that
such information is inaccurate.


     Dated: December 18, 2007


                                         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

                                         3G CAPITAL PARTNERS LTD.

                                         /s/ Alexandre Behring
                                         ------------------------------
                                         Alexandre Behring
                                         Managing Director

                                         3G CAPITAL PARTNERS, L.P.
                                         By:  3G Capital Partners Ltd.
                                         Its: General Partner

                                         /s/ Alexandre Behring
                                         ------------------------------
                                         Alexandre Behring
                                         Managing Director

                                         3G FUND L.P.
                                         By:  3G Capital Partners, L.P.
                                         Its: General Partner

                                         By:  3G Capital Partners Ltd.
                                         Its: General Partner

                                         /s/ Alexandre Behring
                                         ------------------------------
                                         Alexandre Behring
                                         Managing Director

                                         /s/ Alexandre Behring
                                         ------------------------------
                                         Alexandre Behring

                                         /s/ Gilbert H. Lamphere
                                         ------------------------------
                                         Gilbert H. Lamphere

                                         /s/ Timothy T. O'Toole
                                         ------------------------------
                                         Timothy T. O'Toole

                                         /s/ Gary L. Wilson
                                         ------------------------------
                                         Gary L. Wilson