X0202 SCHEDULE 13D/A 0000921895-22-000291 0001640809 XXXXXXXX LIVE 7 Common Stock, par value $0.01 per share 04/20/2026 false 0000352825 350060109 FOSTER L B CO

415 HOLIDAY DR PITTSBURGH PA 15220

ARON R. ENGLISH 206-227-3078 22NW, LP 590 1st Ave. S, Unit C1 Seattle WA 98104 RYAN NEBEL 212-451-2300 OLSHAN FROME WOLOSKY LLP 1325 Avenue of the Americas New York NY 10019 0001640809 N 22NW Fund, LP b WC N DE 261745.00 0.00 261745.00 0.00 261745.00 N 2.5 PN 0001694297 N 22NW, LP b OO N DE 261745.00 0.00 261745.00 0.00 261745.00 N 2.5 PN 0001770575 N 22NW Fund GP, LLC b OO N DE 261745.00 0.00 261745.00 0.00 261745.00 N 2.5 OO 0001783663 N 22NW GP, Inc. b OO N DE 261745.00 0.00 261745.00 0.00 261745.00 N 2.5 CO 0001770436 N English Aron R. b PF OO N X1 262650.00 0.00 262650.00 0.00 262650.00 N 2.5 IN 0001888106 N Hirai-Hadley Bryson b PF N X1 991.00 0.00 991.00 0.00 991.00 N 0.01 IN Common Stock, par value $0.01 per share FOSTER L B CO 415 HOLIDAY DR PITTSBURGH PA 15220 Item 3 is hereby amended and restated to read as follows: The Shares purchased by 22NW Fund were purchased with working capital (which may, at any given time, include margin loans made by brokerage firms in the ordinary course of business). The aggregate purchase price of the 261,745 Shares beneficially owned by 22NW Fund is approximately $2,910,604, excluding brokerage commissions. The Shares directly owned by Mr. English were purchased with personal funds (which may, at any given time, include margin loans made by brokerage firms in the ordinary course of business). The aggregate purchase price of the 905 Shares directly owned by Mr. English is approximately $10,000, excluding brokerage commissions. The Shares directly owned by Mr. Hirai-Hadley were purchased with personal funds (which may, at any given time, include margin loans made by brokerage firms in the ordinary course of business). The aggregate purchase price of the 991 Shares directly owned by Mr. Hirai-Hadley is approximately $15,195, excluding brokerage commissions. Item 5(a) is hereby amended and restated to read as follows: The aggregate percentage of Shares reported owned by each person named herein is based upon 10,458,591 Shares outstanding as of March 19, 2026, which is the total number of Shares outstanding as reported in the Issuer's proxy statement on Schedule 14A filed with the Securities and Exchange Commission on April 10, 2026. As of the date hereof, 22NW Fund directly beneficially owned 261,745 Shares, constituting approximately 2.5% of the Shares outstanding. As of the date hereof, Mr. English directly beneficially owned 905 Shares, constituting approximately 0.01% of the Shares outstanding. As of the date hereof, Mr. Hirai-Hadley directly beneficially owned 991 Shares, constituting approximately 0.01% of the Shares outstanding. 22NW, as the investment manager of 22NW Fund, may be deemed to beneficially own the 261,745 Shares owned by 22NW Fund, constituting approximately 2.5% of the Shares outstanding. 22NW GP, as the general partner of 22NW Fund, may be deemed to beneficially own the 261,745 Shares owned by 22NW Fund, constituting approximately 2.5% of the Shares outstanding. 22NW Inc., as the general partner of 22NW, may be deemed to beneficially own the 261,745 Shares owned by 22NW Fund, constituting approximately 2.5% of the Shares outstanding. Mr. English, as the Portfolio Manager of 22NW, Manager of 22NW GP and President and sole shareholder of 22NW Inc., may be deemed to beneficially own the 261,745 Shares owned by 22NW Fund, which, together with the Shares he directly beneficially owns, constitutes an aggregate of 262,650 Shares, constituting approximately 2.5% of the Shares outstanding. Item 5(c) is hereby amended and restated to read as follows: The transactions in the Shares by the Reporting Persons since the filing of Amendment No. 6 to the Schedule 13D are set forth in Exhibit 1 and are incorporated herein by reference. All of such transactions were effected in the open market unless otherwise noted therein. Item 5(e) is hereby amended and restated to read as follows: As of April 20, 2026, the Reporting Persons ceased to beneficially own more than 5% of the outstanding Shares. Item 7 is hereby amended to add the following exhibit: 1 - Transactions in Securities. 22NW Fund, LP /s/ Aron R. English 04/21/2026 22NW, LP /s/ Aron R. English 04/21/2026 22NW Fund GP, LLC /s/ Aron R. English 04/21/2026 22NW GP, Inc. /s/ Aron R. English 04/21/2026 English Aron R. /s/ Aron R. English 04/21/2026 Hirai-Hadley Bryson /s/ Bryson O. Hirai-Hadley 04/21/2026