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

                                 SCHEDULE 13G/A

                    Under the Securities Exchange Act of 1934
                               (Amendment No. 6)*

                                 L.B. Foster Co.
        -----------------------------------------------------------------
                                (Name of Issuer)

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

                                    350060109
                              --------------------
                                 (CUSIP Number)

                                December 31, 1998
        ----------------------------------------------------------------
             (Date of Event Which Requires Filing of this Statement)

Check the  appropriate box to designate the rule pursuant to which this Schedule
is filed:

      / X / Rule 13d-1(b)
      /   / Rule 13d-1(c)
      /   / Rule 13d-1(d)

*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 the
disclosures provided in a prior cover page.

The information required in 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 the section of the Act
but  shall be  subject  to all other  provisions  of the Act  (however,  see the
Notes).



SCHEDULE 13G/A CUSIP NO. 350060109 1. Names of Reporting Persons. I.R.S. Identification Nos. of above persons (entities only). Quaker Capital Management Corporation -------------------------------------------------------------------------- 2. Check the Appropriate Box if a Member of a Group (a) ----- (b) X ----- 3. SEC Use Only -------------------------------------------------------- 4. Citizenship or Place of Organization Pennsylvania --------------- Number of 5. Sole Voting Power 131,000 Shares --------------- Beneficially 6. Shared Voting Power 417,700 Owned by --------------- Each Reporting 7. Sole Dispositive Power 131,000 Person --------------- With: 8. Shared Dispositive Power 417,700 --------------- 9. Aggregate Amount Beneficially Owned by Each Reporting Person 548,700 ------- 10. Check if the Aggregate Amount in Row (9) Excludes Certain Shares -------- The Reporting Person disclaims beneficial ownership of 417,700 shares owned by its clients. 11. Percent of Class Represented by Amount in Row (9) 5.50% -------------- 12. Type of Reporting Person IA -------------- Page 2 of 4 Pages

SCHEDULE 13G/A CUSIP NO. 350060109 This constitutes Amendment No. 6 to the Schedule 13G of Quaker Capital Management Corporation filed with the Securities and Exchange Commission on February 5, 1993 relating to the Common Stock of L.B. Foster Co., as amended by Amendment No. 1 filed with the Commission on February 10, 1994, Amendment No. 2 filed with the Commission on February 14, 1995, Amendment No. 3 filed with the Commission on February 15, 1996, Amendment No. 4 filed with the Commission on February 11, 1997 and Amendment No. 5 filed with the Commission on February 12, 1998 (the "Schedule 13G"). Item 4 of the Schedule 13G is hereby amended and restated to read as follows: Item 4. Ownership --------- (a) The Reporting Person, in its capacity as investment adviser, may be deemed to be the beneficial owner of 417,700 shares of the Common Stock of the Issuer which are owned by various investment advisory clients of the Reporting Person in accounts over which the Reporting Person has discretionary authority. The filing of this report shall not be construed as an admission that the Reporting Person is, for purposes of Section 13(d) or 13(g) of the Act, the beneficial owner of these securities. Additionally, the Reporting Person and/or its principals own 131,000 shares of the Common Stock of the Issuer. (b) The shares covered by this report represent 5.50% of the Common Stock of the Issuer. (c) None of the clients of the Reporting Person is known to own more than 5% of the Common Stock of the Issuer. The Reporting Person has shared voting and dispositive power over 417,700 shares owned by its clients and held in accounts over which it has discretionary authority. The Reporting Person and/or its principals have sole voting and dispositive power over the 131,000 shares owned by the Reporting Person and/or its principals. Page 3 of 4 Pages

SCHEDULE 13G/A CUSIP NO. 350060109 Item 6 of the Schedule 13G is hereby amended and restated to read as follows: Item 6. Ownership of More than Five Percent on Behalf of Another Person --------------------------------------- 417,700 of the shares with respect to which this report is filed are owned by a variety of investment advisory clients of the Reporting Person, which clients are entitled to receive dividends on and the proceeds from the sale of such shares. No client is known to own more than 5% of the class. SIGNATURE 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. March 24, 1999 -------------------------------- Date /s/ Mark G. Schoeppner -------------------------------- Signature Mark G. Schoeppner, President -------------------------------- Name/Title Page 4 of 4 Pages