This Annual Report on Form 10-K (“Form 10-K”) is being filed by Federal Signal Corporation and its subsidiaries (referred to collectively as the “Company,” “we,” “our” or “us” herein, unless the context otherwise indicates) with the United States (“U.S.”) Securities and Exchange Commission (the “SEC”), and includes comments made by management that may contain words such as “may,” “will,” “believe,” “expect,” “anticipate,” “intend,” “plan,” “project,” “estimate” and “objective” or similar terminology, or the negative thereof, concerning the Company’s future financial performance, business strategy, plans, goals and objectives. These expressions are intended to identify forward-looking statements within the meaning of Section 27A of the Securities Act of 1933, as amended (the “Securities Act”), Section 21E of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), and the Private Securities Litigation Reform Act of 1995. Forward-looking statements include information concerning the Company’s possible or assumed future performance or results of operations and are not guarantees. While these statements are based on assumptions and judgments that management has made in light of industry experience as well as perceptions of historical trends, current conditions, expected future developments and other factors believed to be appropriate under the circumstances, they are subject to risks, uncertainties and other factors that may cause the Company’s actual results, performance or achievements to be materially different.

Federal Signal Corporation, founded in 1901, was reincorporated as a Delaware corporation in 1969. The Company designs, manufactures and supplies a suite of products and integrated solutions for municipal, governmental, industrial and commercial customers. The Company’s portfolio of products that it manufactures includes (i) vehicles and equipment for maintenance and infrastructure end-markets, including sewer cleaners, industrial vacuum loaders, vacuum- and hydro-excavation trucks (collectively, “safe-digging trucks”), street sweepers, waterblasters,waterblasting equipment, road-marking and line-removal equipment, dump truck bodies, trailers, metal extraction support equipment and safetymulti-purpose tractors, and security systems, including technology-based products and solutions for the(ii) public safety market. Following the acquisition of substantially all of the assetsequipment, such as vehicle lightbars and operations of Joe Johnson Equipment, Inc.sirens, industrial signaling equipment, public warning systems and Joe Johnson Equipment (USA), Inc. (collectively, “JJE”) in 2016,general alarm/public address systems. In addition, the Company also distributesengages in the sale of parts, service and re-sells products manufactured by other companies, which include refuse and recycling collection vehicles, camera systems, ice resurfacing equipment and snow-removal equipment. In addition, we sell parts and provide service, repair, equipment rentals and training as part of a comprehensive aftermarket offering to ourits customers. Federal Signal Corporation and its subsidiaries operate 14The Company operates 23 principal manufacturing facilities in five countries around the world and provideprovides products and integrated solutions to customers in all regions of the world.

Products manufactured and supplied, and services rendered, by the Company are divided into two major operatingreportable segments: the Environmental Solutions Group and the 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. Corporate contains those items that are not included in our operatingthe Company’s reportable segments.

During the Company’s discontinuedyear ended December 31, 2023, the Company completed the acquisitions of substantially all of the assets and operations is included in Note 18 – Discontinued Operations toof Trackless Vehicles Limited and Trackless Vehicles Asset Corp, and the accompanying consolidated financial statementswholly-owned subsidiary Work Equipment Ltd. (collectively, “Trackless”) and is incorporated herein by reference.substantially all of the assets and operations of Blasters, Inc. and Blasters Technologies, LLC (collectively, “Blasters”).

Depending primarily on the type and geographic location of the end-customer, the Environmental Solutions Group uses either a dealer network including JJE, or direct sales to serve customers. The acquisition of TBEI increased the number of dealers within our network and also added additional direct sales resources. The dealer network serves both municipal and industrial end markets.end-markets. Within municipal markets, the majority of ourthe Company’s dealers operate exclusively in their assigned territory. In conjunction with selling vehicles to end-customers, dealer representatives demonstrate vehicle functionality and capability and provide vehicle service. In addition to selling products manufactured by the Company, JJE is a distributorcertain of our businesses distribute and re-sell products manufactured by other companies. The Company believes its regional, national and global dealer networks for vehicles is a distinguishing factor from its competitors. The Company has an ownership interest in certain dealers.

No single customer accounted for 10% or more of the Company’s net sales in any year within the three-year period ended December 31, 2017. Of the $1,018.0 million total orders reported in 2017, approximately 35% were from U.S. municipal and governmental customers, 42% were from U.S. commercial and industrial customers and 23% were from non-U.S. customers.

The Company purchases a wide variety of raw materials from around the world for use in the manufacture of its products, although the majority of currentits purchases are currently from North American sources. To minimize risks relating to availability, price and quality of key products and components, the Company is party to numerous strategic supplier arrangements. Although certain materials are obtained from either a single-source supplier or a limited number of suppliers, the Company has generally identified alternative sources to minimize the interruption of its business in the event of supply disruptions. However, a transition to a new supplier may cause the Company to incur supply disruptions and unanticipated costs.

TheAs of December 31, 2023, the Company employed approximately 3,1004,500 people in its businesses at December 31, 2017,located in five countries, with the Company’s U.S. hourly workersemployees accounting for approximately 52%54% of its total workforce. Approximately 18%As of December 31, 2023, approximately 9% of the Company’s U.S. hourly workers were represented by unions at December 31, 2017. We believeunions.

The Company endeavors to establish environmentally-friendly policies and objectives, and believes that these actions are also consistent with cost-effective operating practices. With the application of these policies, the Company believes it complies with federal, state and local provisions that have been enacted or adopted regulating the discharge of materials into the environment, or otherwise relating to the protection of the environment. The Company endeavors to establish environmentally-friendly policies and objectives, and believes that these actions are also consistent with cost-effective operating practices. Capital expenditures in 20172023 attributable to compliance with such laws were not material. The Company also believes that the overall impact of compliance with environmental regulations will not have a material adverse effect on our financial position, results of operations or cash flow.

Certain of the CompanyCompany’s businesses are susceptible to the influences of seasonal factors, including buying orpatterns, delivery patterns. Thepatterns and productivity influences from holiday periods and weather. In general, the Company tends to have lower equipment sales in the first calendar quarter of each year compared to other quarters as a result of these influences.factors. In addition, rental income and parts sales are generally higher in the second and third quarters of the year, because many of the Company’s products are used for maintenance activities in North America, where usage is typically lower during periods of harsher weather conditions.

The following is a list of the Company’s executive officers, including their ages, business experience and positions as of February 1, 2018:2024:

We may occasionally make forward-looking statements and estimates such as forecasts and projections of our future performance or statements of our plans and objectives. These forward-looking statements may be contained in, but are not limited to, filings with the SEC, including this Form 10-K, press releases made by us and oral statements made by our officers. Actual results could differ materially from those contained in such forward-looking statements. Important factors that could cause our actual results to differ from those contained in such forward-looking statements include, but are not limited to, the risks described below.

In 2017,2023, we generated approximately 75%78% of our net sales in the U.S. Our ability to be profitable depends heavily on varying conditions in the U.S. governmental and municipal markets, as well as the overall U.S. economy. The industrial markets in which we compete are subject to considerable cyclicality, and move in response to cycles in the overall business environment. Many of our customers are municipal government agencies, and as a result, we are dependent on municipal government spending. Spending by our municipal customers can be affected by federal, state and local political circumstances, budgetary constraints, changing priorities, actual or potential government shutdowns and other factors. The U.S. government and municipalities depend heavily on tax revenues as a source of spending and accordingly, there is a historical correlation that suggests a lag of one to two years between the condition of the U.S. economy and our sales to the U.S. government and municipalities. Therefore, downturns in the U.S. economy are likely to result in decreases in demand for our products. During previous economic downturns, we experienced decreases in sales and profitability, and we expect our business to remain subject to similar economic fluctuations in the future. In addition, the extent of any potential changes to policies, tax laws and regulations and how any such changes may impact of the enactment of the Tax CutsCompany’s financial results and Jobs Act of 2017 (the “2017 Tax Act”) on the U.S. economyoperations, is currently uncertain. ChangesFor example, the Organization for Economic Co-operation and Development has issued Pillar Two model rules introducing a new global minimum corporate tax of 15% intended to be effective on January 1, 2024. While the U.S. has not yet adopted the Pillar Two rules, various non-U.S. governments are enacting legislation. As currently designed, Pillar Two would apply to our worldwide operations. We currently do not expect these rules to materially increase our global tax costs because we do not have material operations in federal, statejurisdictions with tax rates lower than the Pillar Two minimum. We continue to monitor U.S. and local tax revenues which may result fromglobal legislative action related to Pillar Two for potential impacts.

Government administrations and agencies, political figures, the 2017 Tax Act mayinvestment community, employees and other stakeholders have had an increased focus on sustainability issues and initiatives. Regulatory and other legal changes in laws in response to such matters could require material efforts and costs by us, and our suppliers, to comply with such changes. The costs of compliance with the various laws, regulations and policies applicable to us could be significant and penalties for non-compliance could significantly impact on demand for our products.business.

Our business is subject to fluctuations in demand and changing international economic, legal and political conditions that are beyond our control. In 2017,2023, approximately 25%22% of our net sales were to customers outside the U.S. and we expect a significant portion of our revenues to come from international sales in the foreseeable future. Operating in the international marketplace exposes us to a number of risks, including the need to comply with U.S. and foreign laws and regulations applicable to our foreign operations, such as the Foreign Corrupt Practices Act, the United Kingdom (“U.K.”) Bribery Act and their counterparts in other foreign jurisdictions in which we operate, restrictive domestic and international trade regulations, including the imposition of tariffs and trade barriers on our products, changes in these laws, regulations and policies by the U.S. and foreign governments,governments. In addition, we may be exposed to risks and adverse economic effects associated with changes in tax laws, geopolitical conflicts, actual or threatened imposition of tariffs or trade barriers on our products or materials incorporated into our products, actual or threatened trade disputes, including so-called “trade wars,” political and economic instability in the jurisdictions in which we operate, foreign receivables collection risk and local labor market conditions, and, in some cases, international hostilities. The costs of compliance with these various laws, regulations and policies can be significant and penalties for non-compliance could significantly impact our business.conditions.

We are subjectexposed to a numberinflation effects, which could negatively affect our business, financial condition and results of restrictive debt covenants.

Economic downturns result in tighter credit markets, which could adversely affect our customers’ ability to secure financing or to secure financing at favorable terms or interest rates necessary to proceed or continue with purchases of our products and services. Further, certain government agencies, including the U.S. Treasury, have previously implemented and may continue to implement policies that have resulted and may continue to result in significantly increased interest rates and borrowing costs. Our customers’ or potential customers’ inability to secure financing for projects could result in the delay, cancellation or downsizing of new purchases or the suspension of purchases already under contract, which could cause a decline in the demand for our products and services and negatively impact our financial position, results of operations or cash flow.

We place a high priority on developing new products and services, as well as enhancing our existing products and services. As a result of these efforts, we may be required to expend substantial research, development and marketing resources, and the time and expense required to develop a new product or service or enhance an existing product or service are difficult to predict. We may not succeed in developing, introducing or marketing new products or services or product or service enhancements. In addition, we cannot be certain that any new or enhanced product or service will generate sufficient revenue to justify the expense and resources devoted to the related product diversification effort.

We continue to evaluate opportunities to restructure our business and rationalize our manufacturing operations in an effort to optimize our cost structure. These actions could result in significant charges that could adversely affect our financial condition and results of operations. Future actions could result in restructuring and related charges, including but not limited to impairments, employee termination costs and charges for pension and other postretirement contractual benefits and pension curtailments that could be significant and could have an adverse effect on our financial condition, results of operations or cash flow.

Our ability to operate our businesses and implement our strategies depends in part on the efforts of our executive officers and other key employees. In addition, our future success will depend on, among other factors, our ability to attract and retain qualified personnel. The loss of the services of any key employee or the failure to attract or retain other qualified personnel could have a material adverse effect on our business or business prospects.

Additionally, availability of labor in the markets in which we operate has declined in recent years and competition for such labor has increased. A significant increase in wages paid by competitors for employees similar to our dealer network work force could result in insufficient availability of workers and/or increase our labor costs. In the inabilityevent prevailing wage rates continue to increase in the markets in which we operate, we may be required to concurrently increase the wages paid to our employees to maintain the quality of our dealers to secure adequate access to capitalwork force and customer service. If the supply of skilled labor is constrained or our costs of attracting and maintaining a workforce increase, our profit margins could adversely affect our business.

As a portion of our workforce is unionized, we are subject to risk of work stoppages and other labor relations matters. As of December 31, 2017,2023, approximately 18%9% of our U.S. hourly workers were represented by labor unions and were covered by collective bargaining agreements with various unions. Many of these agreements include provisions that limit our ability to realize cost savings. Any strikes, threats of strikes or other organized disruptions in connection with the negotiation of new labor agreements or other negotiations could materially adversely affect our business as well as impair our ability to implement further measures to reduce costs and improve production efficiencies. In addition, the stoppage of work for a prolonged period of time at one, or several, of our principal manufacturing facilities, due to public health concerns, or any other reason, could materially adversely affect our business.

Our funding obligations and pension expense for our defined benefit pension plans are driven by the performance of assets set aside in trusts for these plans, the discount rate used to value the plans’ liabilities, actuarial assumptions and experience and legal and regulatory funding requirements. Changes in these factors could have an adverse impact on our financial condition, results of operations or cash flow. In addition, a portion of our pension plan assets are invested in equity securities, which can experience significant declines if financial markets weaken. The level of the funding of our defined benefit pension plan liabilities was approximately 80%88% as of December 31, 2017.2023. Funding of the Company’s U.S. defined benefit pension plan is determined in accordance with guidelines set forth in the Employee Retirement Income Security Act (“ERISA”). The current year funding status was impacted by a lower discount rate than in the prior year.Act. Our future pension expenses and funding requirements could increase significantly due to the effect of adverse changes in the discount rate, asset values or the estimated expected return on plan assets. In addition, we could become legally required to make increased cash contributions to the pension plans, and these contributions could be material and negatively affect our cash flow.

We, like other manufacturers, continue to face heavy governmental regulation of our products, especially in the areas of the environment and employee health and safety. Increased public awareness and concern regarding climate change and other related matters at numerous levels of government in various jurisdictions may lead to additional international, national, regional and local legislative and regulatory responses, and compliance with any new rules could be difficult and costly. These regulations could include environmental requirements applicable to manufacturing and vehicle emissions and regulations impacting our supply chain both nationally and internationally. Complying with environmental, safety and safety requirementsother regulations has added and will continue to add to the cost of our products, and could increase the capital required to support our business.business and could affect the products and services that we offer. While we believe that we are in compliance in all material respects with these laws and regulations, we may be adversely impacted by costs, liabilities or claims with respect to our operations under existing laws or those that may be adopted. These requirements are complex, change frequently and have tended to become more stringent over time. Therefore, we could incur substantial costs, including cleanup costs, fines and civil or criminal sanctions as a result of violation of, or liabilities under, environmental laws and safety regulations. Further, climate change regulations at the federal, state or local level or in international jurisdictions could require us to limit emissions, change our manufacturing processes or product offerings, or undertake other activities which may require us to incur additional expense. These requirements may increase the cost of our products, which may diminish demand for those products. In addition,Additionally, uneven application of environmental, or safety and other regulations could place our products at a cost or features disadvantage, which could reduce our revenues and profitability.

None.

As of December 31, 2017,2023, the Company utilized ten17 principal manufacturing plants located throughout the U.S., as well as two in Europe, onethree in Canada and one in South Africa. The Company also leases facilities within the U.S., Europe and Canada from which we provide sales, service and/or equipment rentals. As of December 31, 2017,2023, the Company devoted approximately 1.62.5 million square feet to manufacturing and 0.71.2 million square feet to sales, service, warehousing and office space. Of the total square footage, approximately 77%84% is devoted to the Environmental Solutions Group and 23%16% to the Safety and Security

The information concerning the Company’s legal proceedings included in Note 1113 – Legal Proceedings to the accompanying consolidated financial statements is incorporated herein by reference.

Not applicable.

As of January 31, 2018,2024, there were 1,5971,463 holders of record of the Company’s common stock.

Information concerning the Company’s equity compensation plans is included under Item 12 of Part III of this Form 10-K.

Management’s Discussion and Analysis of Financial Condition and Results of Operations (“MD&A”) is designed to provide information that is supplemental to, and shall be read together with, the consolidated financial statements and the accompanying notes contained in this Form 10-K. Information in MD&A is intended to assist the reader in obtaining an understanding of (i) the consolidated financial statements, (ii) the Company’s business segments and how the results of those segments impact the Company’s results of operations and financial condition as a whole and (iii) how certain accounting principles affect the Company’s consolidated financial statements.

The Company is a leading global manufacturer and supplier of (i) vehicles and equipment for maintenance and infrastructure end-markets, including sewer cleaners, industrial vacuum loaders, safe-digging trucks, street sweepers, waterblasting equipment, road-marking and line-removal equipment, dump truck bodies, trailers, metal extraction support equipment and trailersmulti-purpose tractors, and (ii) public safety security and communication equipment, such as lights,vehicle lightbars and sirens, industrial signaling equipment, public warning systems and warninggeneral alarm/public address systems. Following the acquisition of JJE in 2016, the Company also distributes and re-sells products manufactured by other companies, which include refuse and recycling collection vehicles, camera systems, ice resurfacing equipment and snow-removal equipment. In addition, we sellengage in the sale of parts, service and provide service, repair, equipment rentals and training as part of a comprehensive aftermarket offering to our customer base. We operate 1423 manufacturing facilities in five countries around the world and provide products and integrated solutions to municipal, governmental, industrial and commercial customers in all regions of the world.

Conditions in our end markets remained strong throughout 2023, with demand for our products and services at unprecedented levels. We continued to focus on executingexecute against its key long-term objectives, includingour organic growth initiatives, and with contributions from our recent value-added acquisitions and additional efficiency gains resulting from the application of our eighty-twenty initiatives, we were able to sustain a high level of financial performance. As the year progressed, we saw improvement in supply chain conditions, which facilitated increased production levels at several of our facilities and, despite some lingering supply chain-related operational inefficiencies, we were able to deliver record financial results for our stockholders, with double-digit year-over-year top line and earnings growth, margin expansion and significant improvement in cash flow generation.

Included among the Company’s highlights in 2023 were the following:

The following table summarizes our Consolidated Statements of Operations as of, and for the years ended, December 31, 2023, 2022 and 2021, and illustrates the key financial indicators used to assess our consolidated financial results:

Net sales for the year ended December 31, 2023 increased by $287.9 million, or 20%, compared to the prior year.year, inclusive of the effects of acquisitions, pricing actions and increased chassis sales. The Environmental Solutions Group reported a net sales increase of $247.3 million, or 21%, primarily due to a $66.2 million improvement in aftermarket revenues and increases in sales of street sweepers, sewer cleaners, refuse trucks, multi-purpose tractors, metal extraction support equipment, industrial vacuum loaders, safe-digging trucks, trailers and road-marking and line-removal equipment of $38.6 million, $35.0 million, $31.1 million, $21.4 million, $17.2 million, $16.3 million, $15.5 million, $10.5 million and $7.4 million, respectively. Partially offsetting these improvements was a reduction in sales of hoists and waterblasting equipment of $7.9 million and $5.1 million, respectively, as well as a $6.4 million unfavorable foreign currency translation impact. Within the Environmental Solutions Safety and Security Systems

Group, net sales increased by $201.9$40.6 million, or 41%, largely due to the addition of $109.4 million of net sales from the TBEI acquisition, approximately $54.7 million of incremental net sales resulting from the prior-year JJE acquisition, including increases in rental income and sales of used equipment, and improved domestic sales of sewer cleaners and vacuum trucks. In the Safety and Security Systems Group, net sales decreased by $11.3 million, or 5%17%, primarily due to lowerimprovements in sales into globalof public safety marketsequipment, industrial signaling equipment and decreased saleswarning systems of outdoor warning systems.$22.7 million, $11.0 million and $6.8 million, respectively.

For the year ended December 31, 2017,2023, cost of sales increased by $152.5$182.6 million, or 29%17%, compared to the prior year, largely due to an increase of $162.1$162.3 million, or 42%17%, within the Environmental Solutions Group, primarily driven byrelated to increased sales volumes, additional costinclusive of sales from the TBEI acquisition and the effects of a full year of JJE activity in the current-year period compared with seven months last year, recognition of approximately $0.8 million more expense associated with purchase accounting effectsacquisitions, increased chassis costs and a $6.5$3.2 million increase in depreciation expense, largely resulting from depreciation on rental equipment acquired in the JJE transaction. This increase was partially offset by a decrease in cost of sales of $9.6$6.2 million or

For the year ended December 31, 2017,2023, gross profit increased by $38.1$105.3 million, or 21%31%, compared to the prior year, primarily due to a $39.8$85.0 million improvement inwithin the Environmental Solutions Group partially offset byand a $1.7$20.3 million reductionincrease within the Safety and Security Systems Group. Gross marginprofit as a percentage of net sales (“gross profit margin”) for the year ended December 31, 20172023 was 24.6%26.1%, compared to 25.9%24.0% in the prior year, largely due to incremental depreciation expense and purchase accounting expense effects, partially offsetprimarily driven by gross margin improvementimprovements within the Environmental Solutions Group and Safety and Security Systems Group related to the savings associated with materialof 220 basis points and labor cost reduction initiatives.180 basis points, respectively.

For the year ended December 31, 2017,2023, SEG&A expenses increased by $22.4$38.4 million, or 18%22%, compared to the prior year, primarily represented by a $21.0due to increases of $16.8 million, increase$6.3 million and $15.3 million within the Environmental Solutions Group, largely the result of the addition of expenses of businesses acquired in the current and prior year, a $4.7 million increase in amortization expense and strategic investments in our sales force to support our organic growth initiatives. SEG&A expenses with the Safety and Security Systems Group decreased by $0.6 millionand Corporate, respectively. As a percentage of net sales, SEG&A expenses increased from 12.0% in comparison to the prior year, while Corporate SEG&A expenses increased by $2.0 million, primarily driven byto 12.2% in the recognition of $0.7 million in executive severance costs, increased legal expenses associated with hearing loss litigation and higher employee incentive compensation costs, partially offset by lower pension expenses.current year.

Operating income for the year ended December 31, 20172023 increased by $9.4$63.7 million, or 16%40%, to $67.1 million, primarily driven by a $18.3 million operating income improvement within the Environmental Solutions Group, associated with increased sales volumes, a $6.2 million operating income contribution from TBEI and the effects of including a full year of operating income from JJE in 2017, compared to only seven months in the prior year. TBEI’s operating income contribution in the current-year period included the effects of amortization expense on intangible assets acquired, which, coupled with the increased JJE activity, contributed to an increase in the Environmental Solutions Group’s depreciation and amortization expense of $11.2 million. In addition, there was a $0.8 million increase in purchase accounting expense effects and a $0.5 million increase in acquisition-related costs in the current year. Within the Safety and Security Systems Group, operating income in the year ended December 31, 2017 was unchanged from the prior year, at $27.0largely due to the $105.3 million with reductions in SEG&A expenses and restructuring expenses of $0.6 million and $1.1 million, respectively, offsetting a $1.7 million decreaseimprovement in gross profit. In addition toprofit, partially offset by the $2.0$38.4 million increase in SEG&A expenses, corporate expensesa $2.3 million increase in the year ended December 31, 2017 also includedamortization expense and a $6.1 million pension settlement charge, a $0.8$0.9 million increase in acquisition-related expenses and higher expenses associated with hearing loss litigation.costs. Consolidated operating margin for the year ended December 31, 2017, inclusive of the incremental depreciation and amortization, purchase accounting expense effects, pension and hearing loss settlement charges and acquisition costs,2023 was 7.5%13.0%, compared to 8.2%11.2% in the prior year.

Interest expense for the year ended December 31, 20172023 increased by $5.4$9.4 million, or 284%91%, compared to the prior year, largely due to higher average debt levels following the acquisition of TBEI. For further discussion, see Note 7 – Debt to the accompanying consolidated financial statements.an increase in interest rates.

For the year ended December 31, 2017, other2023, Other expense (income) expense,, net, totaled $1.2increased by $2.2 million of income, largelycompared to the prior year, primarily due to a $1.0 million increase in net periodic pension expense, a $0.8 million increase in estimated environmental remediation costs associated with a business discontinued in 2009, and a $0.4 million increase in foreign currency transaction gains, whereas for the year ended December 31, 2016, $1.3 million of income was reported, largely related to a gain on the settlement of a foreign currency forward contract and interest income on a loan provided to a customer.losses.

Net income for the year ended December 31, 2017, compared with $39.4 million in the prior year, largely due to the improved operating income, the $16.9 million reduction in income tax expense and the absence of $0.3 million in debt settlement charges in connection with the Company’s prior-year debt refinancing, partially offset2023 increased by the $5.4 million increase in interest expense, associated with higher average debt levels following the acquisition of TBEI, and the $0.1 million reduction in other income.

ForAdjusted EBITDA for the year ended December 31, 2016, gross profit decreased by $42.52023 was $286.0 million, or 19%, consisting of reductions withincompared to $215.0 million in the Environmental Solutions Group and the Safety and Security Systems Group of $36.4 million and $6.1 million, respectively. Grossprior year. Adjusted EBITDA margin for the year ended December 31, 2016 decreased to 25.9%2023 was 16.6%, from 29.4% in the prior year, largely due to reduced operating leverage due to lower sales volumes, unfavorable sales mix, with fewer sales into industrial markets and a higher concentration of sales of products manufactured by other companies, which tend to carry lower margins, as well as purchase accounting expense effects, within the Environmental Solutions Group.

The following table summarizes the Environmental Solutions Group’s operating results as of, and for the years ended, December 31, 2017, 20162023, 2022 and 2015:2021:

Total orders increased by $331.5$133.8 million, or 70%9%, for the year ended December 31, 2017.2023, inclusive of the effects of acquisitions and pricing actions. U.S. orders increased by $295.9$73.1 million, largelyor 6%, primarily due to improvements in orders for sewer cleaners, vacuum trucks and street sweepers, road-marking and line-removal equipment, dump truck bodies, multi-purpose tractors, industrial vacuum loaders and refuse trucks of $49.7$26.9 million, $43.1$22.9 million, $19.5 million, $12.0 million, $9.5 million and $32.5$6.4 million, respectively, as well as the impact of the TBEI acquisition, which contributed $151.9 million of orders. Street sweeper and sewer cleaner orderrespectively. Additionally, aftermarket demand increased by $43.2 million. Partially offsetting these improvements were primarily driven by increased demand within municipal and

The following table summarizes the Safety and Security Systems Group’s operating results as of, and for the years ended, December 31, 2017, 20162023, 2022 and 2015:2021:

Total orders increased by $12.1$44.1 million, or 6%18%, for the year ended December 31, 2017. In the aggregate,2023. U.S. orders increased by $6.9$16.9 million, or 11%, compared to the prior year, driven by increasesimprovements in orders of outdoorfor public safety equipment, warning systems public safety products and industrial productssignaling equipment of $3.4$10.8 million, $2.9$4.9 million and $0.6$1.2 million, respectively. Non-USNon-U.S. orders increased by $5.2$27.2 million, largelyor 31%, primarily due to a $6.8$23.9 million increaseimprovement in orders for public safety equipment, inclusive of a large fleet order from international industrial markets, including oil and gas and coal markets, partially offset by a $1.6customer in Mexico, as well as a $2.8 million decreaseimprovement in orders of international public safety products.for warning systems.

Corporate operating expenses were $32.3$39.5 million, $23.4$24.5 million and $26.0$22.5 million for the years ended December 31, 2017, 20162023, 2022 and 2015,2021, respectively.

The Company useduses its cash flow from operations to fund growth and to make capital investments that sustain its operations, reduce costs, or both. Beyond these uses, remaining cash is used to pay down debt, repurchase shares, fund dividend payments and make pension contributions. The Company may also choose to invest in the acquisition of businesses. In the absence of significant unanticipated cash demands, we believe that the Company’s existing cash balances, cash flow from operations and borrowings available under the Amended 20162022 Credit Agreement will provide funds sufficient for these purposes. The net cash flows associated with the Company’s rental equipment transactions are included in cash flow from operating activities. Subsequent to the acquisition of JJE, net cash flows from rental equipment transactions may become more significant, and as such, cash flow from operating activities may not be directly comparable with amounts reported in periods prior to the acquisition.