Summary of Significant Accounting Policies (Policies)	6 Months Ended
Jun. 30, 2025
Accounting Policies [Abstract]
Organization and Description of the Business	Organization and Description of the Business Federal Signal Corporation was founded in 1901 and was reincorporated as a Delaware corporation in 1969. References herein to the “Company,” “we,” “our,” or “us” refer collectively to Federal Signal Corporation and its subsidiaries. Products manufactured and services rendered by the Company are divided into two reportable segments: Environmental Solutions Group and Safety and Security Systems Group. The individual operating businesses are organized as such because they share certain characteristics, including technology, marketing, distribution and product application, which create long-term synergies. These segments are discussed in Note 12 – Segment Information.
Basis of Presentation and Consolidation	Basis of Presentation and Consolidation The accompanying unaudited condensed consolidated financial statements represent the consolidation of Federal Signal Corporation and its subsidiaries included herein and have been prepared by the Company pursuant to the rules and regulations of the United States (“U.S.”) Securities and Exchange Commission (the “SEC”). Certain information and footnote disclosures normally included in financial statements prepared in accordance with U.S. generally accepted accounting principles (“GAAP”) have been condensed or omitted pursuant to such rules and regulations, although the Company believes that the disclosures presented herein are adequate to ensure the information presented is not misleading. Except as otherwise noted, these condensed consolidated financial statements have been prepared in accordance with the Company’s accounting policies described in the Company’s Annual Report on Form 10-K for the year ended December 31, 2024, and should be read in conjunction with those consolidated financial statements and the notes thereto. These condensed consolidated financial statements include all normal and recurring adjustments that we considered necessary to present a fair statement of our results of operations, financial condition, and cash flow. Intercompany balances and transactions have been eliminated in consolidation. The results reported in these condensed consolidated financial statements should not be regarded as necessarily indicative of results that may be expected for the entire year, which may differ materially due to, among other things, the risk factors described under Part I, Item 1A, Risk Factors, of the Company’s Annual Report on Form 10-K for the year ended December 31, 2024, which was filed with the SEC on February 26, 2025. While we label our quarterly information using a calendar convention whereby our first, second, and third quarters are labeled as ending on March 31, June 30, and September 30, respectively, it is our longstanding practice to establish interim quarterly closing dates based on a 13-week period ending on a Saturday, with our fiscal year ending on December 31. The effects of this practice are not material and exist only within a reporting year.
Recent Accounting Pronouncements and Accounting Changes	Recent Accounting Standard Adoptions In November 2023, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2023-07, Segment Reporting (Topic 280): Improvements to Reportable Segment Disclosures, which expands annual and interim disclosure requirements for reportable segments, including enhanced disclosures regarding significant segment expenses. ASU 2023-07 was effective for fiscal years beginning after December 15, 2023, and for interim periods within fiscal years beginning after December 15, 2024, with early adoption permitted. The Company adopted this ASU effective for the fiscal year ended December 31, 2024, and has included the required interim disclosures for all periods presented in Note 12 - Segment Information. Recent Accounting Pronouncements In December 2023, the FASB issued ASU 2023-09, Income Taxes (Topics 740): Improvements to Income Tax Disclosures, which expands the disclosure requirements for income taxes. ASU 2023-09 is effective prospectively for annual periods beginning after December 15, 2024, with early adoption and retrospective application permitted. The Company is currently evaluating the impact of adopting this guidance on its financial statement disclosures. In November 2024, the FASB issued ASU 2024-03, Income Statement - Reporting Comprehensive Income-Expense Disaggregation Disclosures (Subtopic 220-40), which requires entities to disclose, on an annual and interim basis, disaggregated information about certain income statement expense line items. ASU 2024-03 is effective prospectively for annual periods beginning after December 15, 2026, and for interim periods within fiscal years beginning after December 15, 2027, with early adoption and retrospective adoption permitted. The Company is currently evaluating the impact of adopting this guidance on its financial statement disclosures.
Use of Estimates	Use of Estimates The preparation of consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect (i) the reported amounts of assets and liabilities, (ii) the disclosure of contingent assets and liabilities at the date of the condensed consolidated financial statements, and (iii) the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates.
Fair Value Measurements	The Company uses a three-level fair value hierarchy that prioritizes the inputs used to measure fair value. This hierarchy maximizes the use of observable inputs and minimizes the use of unobservable inputs. Observable inputs are developed based on market data obtained from independent sources, while unobservable inputs reflect the Company’s assumptions about valuation based on the best information available in the circumstances. The three levels of inputs are classified as follows: •Level 1 — quoted prices in active markets for identical assets or liabilities; •Level 2 — observable inputs, other than quoted prices included in Level 1, such as quoted prices for markets that are not active, or other inputs that are observable or can be corroborated by observable market data; and •Level 3 — unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities, including certain pricing models, discounted cash flow methodologies, and similar techniques that use significant unobservable inputs. In determining fair value, the Company uses various valuation approaches within the fair value measurement framework. The valuation methodologies used for the Company’s assets and liabilities measured at fair value and their classification in the valuation hierarchy are summarized below. Cash Equivalents Cash equivalents primarily consist of time-based deposits and interest-bearing instruments with maturities of three months or less. The Company classified cash equivalents as Level 1 due to the short-term nature of these instruments and measured the fair value based on quoted prices in active markets for identical assets. Interest Rate Swaps As described in Note 5 – Debt, the Company may, from time to time, execute interest rate swaps as a means of fixing the floating interest rate component on a portion of its floating-rate debt. The Company classifies its interest rate swaps as Level 2 due to the use of a discounted cash flow model based on the terms of the contract and the interest rate curve (Level 2 inputs) to calculate the fair value of the swaps. Contingent Consideration As of June 30, 2025, the Company had contingent obligations to transfer up to $3.9 million, $4.8 million, and $15.0 million to the former owners of Blasters, Inc. and Blasters Technologies, LLC (collectively, “Blasters”); Standard; and Hog, respectively, if specified financial results are met over future reporting periods (i.e., an earn-out). The Blasters, Standard, and Hog acquisitions were completed on January 3, 2023, October 4, 2024, and February 12, 2025, respectively. The Blasters contingent earn-out payments, if earned, would be due to be paid annually, in each of the three years following the anniversary of the closing date. There was no contingent earn-out payable for the first or second annual measurement periods. The Standard contingent earn-out payment, if earned, would be due to be paid following the end of the performance period, which concludes on January 1, 2027. The Hog contingent earn-out payment, if earned, would be due to be paid following the end of the performance period, which concludes on December 31, 2025. The Company also previously had contingent obligations to transfer up to $7.5 million to the former owners of Deist Industries, Inc., Bucks Fabricating, LLC, Roll-Off Parts, LLC, and Switch-N-Go LLC (collectively, “Deist”) and up to C$6.0 million to the former owner of Trackless. The applicable performance period for the Deist earn-out ended on December 30, 2024, the third anniversary of the closing date. During the second quarter of 2025, the Company determined that no additional consideration was payable to the former owners of Deist. The applicable performance period for the Trackless earn-out ended on April 3, 2025, the second anniversary of the closing date. During the second quarter of 2025, the Company determined that, based on the achievement of certain financial results, the full amount of the contingent consideration had been earned, and paid an additional C$6.0 million (approximately $4.4 million) to the former owner of Trackless. See Note 2 - Acquisitions for additional information. Liabilities for contingent consideration are measured at fair value each reporting period, with the acquisition-date fair value included as part of the consideration transferred. Subsequent changes in fair value are included as a component of Acquisition and integration-related expenses, net on the Condensed Consolidated Statements of Operations. The Company uses an income approach to value the contingent consideration liability based on the present value of risk-adjusted future cash flows under either a scenario-based or option-pricing method, as appropriate. Due to the lack of relevant observable market data over fair value inputs, such as prospective financial information or probabilities of future events as of June 30, 2025, the Company has classified the contingent consideration liability within Level 3 of the fair value hierarchy outlined in ASC 820, Fair Value Measurements.

Summary of Significant Accounting Policies (Policies)

6 Months Ended

Jun. 30, 2025

Organization and Description of the Business

Federal Signal Corporation was founded in 1901 and was reincorporated as a Delaware corporation in 1969. References herein to the “Company,” “we,” “our,” or “us” refer collectively to Federal Signal Corporation and its subsidiaries.

Products manufactured and services rendered by the Company are divided into two reportable segments: Environmental Solutions Group and Safety and Security Systems Group. The individual operating businesses are organized as such because they share certain characteristics, including technology, marketing, distribution and product application, which create long-term synergies. These segments are discussed in Note 12 – Segment Information.

Basis of Presentation and Consolidation

The accompanying unaudited condensed consolidated financial statements represent the consolidation of Federal Signal Corporation and its subsidiaries included herein and have been prepared by the Company pursuant to the rules and regulations of the United States (“U.S.”) Securities and Exchange Commission (the “SEC”). Certain information and footnote disclosures normally included in financial statements prepared in accordance with U.S. generally accepted accounting principles (“GAAP”) have been condensed or omitted pursuant to such rules and regulations, although the Company believes that the disclosures presented herein are adequate to ensure the information presented is not misleading. Except as otherwise noted, these condensed consolidated financial statements have been prepared in accordance with the Company’s accounting policies described in the Company’s Annual Report on Form 10-K for the year ended December 31, 2024, and should be read in conjunction with those consolidated financial statements and the notes thereto.

These condensed consolidated financial statements include all normal and recurring adjustments that we considered necessary to present a fair statement of our results of operations, financial condition, and cash flow. Intercompany balances and transactions have been eliminated in consolidation.

The results reported in these condensed consolidated financial statements should not be regarded as necessarily indicative of results that may be expected for the entire year, which may differ materially due to, among other things, the risk factors described under Part I, Item 1A, Risk Factors, of the Company’s Annual Report on Form 10-K for the year ended December 31, 2024, which was filed with the SEC on February 26, 2025. While we label our quarterly information using a calendar convention whereby our first, second, and third quarters are labeled as ending on March 31, June 30, and September 30, respectively, it is our longstanding practice to establish interim quarterly closing dates based on a 13-week period ending on a Saturday, with our fiscal year ending on December 31. The effects of this practice are not material and exist only within a reporting year.

Recent Accounting Pronouncements and Accounting Changes

Recent Accounting Standard Adoptions

In November 2023, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2023-07, Segment Reporting (Topic 280): Improvements to Reportable Segment Disclosures, which expands annual and interim disclosure requirements for reportable segments, including enhanced disclosures regarding significant segment expenses. ASU 2023-07 was effective for fiscal years beginning after December 15, 2023, and for interim periods within fiscal years beginning after December 15, 2024, with early adoption permitted. The Company adopted this ASU effective for the fiscal year ended December 31, 2024, and has included the required interim disclosures for all periods presented in Note 12 - Segment Information.

Recent Accounting Pronouncements

In December 2023, the FASB issued ASU 2023-09, Income Taxes (Topics 740): Improvements to Income Tax Disclosures, which expands the disclosure requirements for income taxes. ASU 2023-09 is effective prospectively for annual periods beginning after December 15, 2024, with early adoption and retrospective application permitted. The Company is currently evaluating the impact of adopting this guidance on its financial statement disclosures.

In November 2024, the FASB issued ASU 2024-03, Income Statement - Reporting Comprehensive Income-Expense Disaggregation Disclosures (Subtopic 220-40), which requires entities to disclose, on an annual and interim basis, disaggregated information about certain income statement expense line items. ASU 2024-03 is effective prospectively for annual periods beginning after December 15, 2026, and for interim periods within fiscal years beginning after December 15,

2027, with early adoption and retrospective adoption permitted. The Company is currently evaluating the impact of adopting this guidance on its financial statement disclosures.

Use of Estimates

The preparation of consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect (i) the reported amounts of assets and liabilities, (ii) the disclosure of contingent assets and liabilities at the date of the condensed consolidated financial statements, and (iii) the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates.

Fair Value Measurements

The Company uses a three-level fair value hierarchy that prioritizes the inputs used to measure fair value. This hierarchy maximizes the use of observable inputs and minimizes the use of unobservable inputs. Observable inputs are developed based on market data obtained from independent sources, while unobservable inputs reflect the Company’s assumptions about valuation based on the best information available in the circumstances. The three levels of inputs are classified as follows:

•Level 1 — quoted prices in active markets for identical assets or liabilities;

•Level 2 — observable inputs, other than quoted prices included in Level 1, such as quoted prices for markets that are not active, or other inputs that are observable or can be corroborated by observable market data; and

•Level 3 — unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities, including certain pricing models, discounted cash flow methodologies, and similar techniques that use significant unobservable inputs.

In determining fair value, the Company uses various valuation approaches within the fair value measurement framework. The valuation methodologies used for the Company’s assets and liabilities measured at fair value and their classification in the valuation hierarchy are summarized below.

Cash Equivalents

Cash equivalents primarily consist of time-based deposits and interest-bearing instruments with maturities of three months or less. The Company classified cash equivalents as Level 1 due to the short-term nature of these instruments and measured the fair value based on quoted prices in active markets for identical assets.

Interest Rate Swaps

As described in Note 5 – Debt, the Company may, from time to time, execute interest rate swaps as a means of fixing the floating interest rate component on a portion of its floating-rate debt. The Company classifies its interest rate swaps as Level 2 due to the use of a discounted cash flow model based on the terms of the contract and the interest rate curve (Level 2 inputs) to calculate the fair value of the swaps.

Contingent Consideration

As of June 30, 2025, the Company had contingent obligations to transfer up to $3.9 million, $4.8 million, and $15.0 million to the former owners of Blasters, Inc. and Blasters Technologies, LLC (collectively, “Blasters”); Standard; and Hog, respectively, if specified financial results are met over future reporting periods (i.e., an earn-out). The Blasters, Standard, and Hog acquisitions were completed on January 3, 2023, October 4, 2024, and February 12, 2025, respectively. The Blasters contingent earn-out payments, if earned, would be due to be paid annually, in each of the three years following the anniversary of the closing date. There was no contingent earn-out payable for the first or second annual measurement periods. The Standard contingent earn-out payment, if earned, would be due to be paid following the end of the performance period, which concludes on January 1, 2027. The Hog contingent earn-out payment, if earned, would be due to be paid following the end of the performance period, which concludes on December 31, 2025.

The Company also previously had contingent obligations to transfer up to $7.5 million to the former owners of Deist Industries, Inc., Bucks Fabricating, LLC, Roll-Off Parts, LLC, and Switch-N-Go LLC (collectively, “Deist”) and up to C$6.0 million to the former owner of Trackless. The applicable performance period for the Deist earn-out ended on December 30, 2024, the third anniversary of the closing date. During the second quarter of 2025, the Company determined that no additional consideration was payable to the former owners of Deist. The applicable performance period for the Trackless earn-out ended on April 3, 2025, the second anniversary of the closing date. During the second quarter of 2025, the Company determined that, based on the achievement of certain financial results, the full amount of the contingent consideration had been earned, and paid an additional C$6.0 million (approximately $4.4 million) to the former owner of Trackless. See Note 2 - Acquisitions for additional information.

Liabilities for contingent consideration are measured at fair value each reporting period, with the acquisition-date fair value included as part of the consideration transferred. Subsequent changes in fair value are included as a component of Acquisition and integration-related expenses, net on the Condensed Consolidated Statements of Operations.

The Company uses an income approach to value the contingent consideration liability based on the present value of risk-adjusted future cash flows under either a scenario-based or option-pricing method, as appropriate. Due to the lack of relevant

observable market data over fair value inputs, such as prospective financial information or probabilities of future events as of June 30, 2025, the Company has classified the contingent consideration liability within Level 3 of the fair value hierarchy outlined in ASC 820, Fair Value Measurements.