Fourth quarter revenue grew over 14% to $1.7 billion and adjusted earnings per share increased 23%, representing a great finish to our fiscal 2021 year, where revenue of $6.2 billion was accompanied by an adjusted earnings per share increase of 47% to $3.58.
I'm pleased with the progress we've made in enhancing our overall profitability as full year adjusted EBITDA margins reached a record 7.3% and fourth quarter adjusted EBITDA margins increased 40 basis points from prior year.
Going forward, we expect that ongoing concerns around COVID-19 variance will lead to incremental opportunities for our disinfection services, providing support for our adjusted EBITDA margins exceeding 6% in fiscal 2022 per our guidance.
This industry group, which was most impacted by the pandemic, generated 43% year-over-year revenue growth in the fourth quarter as air travel trends improved markedly over the prior year and we capitalized on new business opportunities, including the expansion of our parking operations at airports.
Our fourth quarter was also benefited from 21% growth in Technical Solutions revenue, reflecting growth in our emerging e-mobility business and improved access to client-site.
Technical Solutions backlog increased by 20% sequentially compared to the third quarter and reached a record level in the fourth quarter, driven by the transition to electric vehicles and the associated need for charging stations, our e-mobility business has significant long-term growth potential.
Key growth drivers for this business include federal stimulus funds designated for energy efficient projects as well as the recent passage of the federal infrastructure bill that included $7.5 billion toward deploying EV charging stations nationwide.
The total Elevate investment is estimated to be $150 million to $175 million and the initiatives is expected to be largely completed by the end of fiscal 2025.
In fiscal '22, we expect to invest approximately $80 million in Elevate, enabling us to significantly advance the implementation of our digital transformation.
For fiscal 2022, we forecast GAAP earnings per diluted share of $2.05 to $2.30 and adjusted earnings per share of $3.30 to $3.55.
Within this guidance, we assume an easing of COVID related disinfection services and work orders, leading us to project fiscal '22 adjusted EBITDA margins of 6.2% to 6.6%, inclusive of synergies from Able Services acquisition.
While earnings per share and margins are projected to decline from fiscal 2021, they are significantly above pre-pandemic levels and above our targeted long-term metrics we outlined in 2019 when we signaled an aspirational margin range of 5.5% to 6%.
Fourth quarter revenue increased 14.2% to $1.7 billion, primarily driven by one month of contribution from the acquisition Able Services, continued client demand for disinfection services and a generally improving economic environment.
GAAP income from continuing operations in the fourth quarter was $34.3 million or $0.50 per diluted share, compared to $53.1 million or $0.78 per diluted share in the same period last year.
The decrease in GAAP income reflects higher operating and corporate expenses, which included acquisition related costs of $19.7 million, initial investments in our Elevate initiative and a lower benefit from self-insurance adjustments related to prior years.
On an adjusted basis, fourth quarter income from continuing operations grew 25% to $58.2 million or $0.85 per diluted share compared to $46.7 million or $0.69 per diluted share in the fourth quarter of last year.
Corporate expenses were $40.9 million higher compared to the fourth quarter of fiscal 2020, due to acquisition-related expenses, a lower benefit from prior year self-insurance adjustments and costs related to hiring initiatives.
Corporate expenses in the fourth quarter of fiscal 2021 were also impacted by $10.3 million of initial investments in the Elevate transformation initiative that Scott mentioned, and that we will discuss more fully later on.
B&I revenue increased 17.5% year-over-year to $933 million, driven primarily by a one-month contribution from Able Services, increased office occupancy and the expansion of key accounts.
Excluding the contribution from Able, B&I revenue increased 4.7% from the prior period.
Operating profit in B&I declined 3% to $82.1 million from the same period last year, reflecting an easing in higher margin work orders.
Aviation revenue increased 43% to $201.7 million, marking the second consecutive quarter of robust year-over-year revenue growth.
Aviation operating profit increased to $13.2 million, compared to $3.5 million in last year's fourth quarter, driven by the significant rebound in revenue as well as our efforts to emphasize higher margin airport facility services.
Revenue within our Technology & Manufacturing segment was essentially flat year-over-year at $245.5 million, as new business starts were offset by reduced client demand for COVID related work orders and EnhancedClean.
However, operating margins for T&M improved to 10% in the fourth quarter, up 40 basis points from last year's fourth quarter benefiting from efficient labor management and contract expansions.
Education revenue declined 3.7% to $204.4 million, largely reflecting the timing of contract rebids.
Operating profit totaled $7.7 million, down from $15.1 million in last year's fourth quarter.
Moving forward, we anticipate Education segment profit margins will be approximately 6% in fiscal 2022, representing an increase of more than 100 basis points compared to pre-COVID levels, resulting from a sustained uplift in labor efficiency and higher disinfection revenue.
Revenue within our Technical Solutions segment grew 21% to [Technical Issues] million, aided by continued strong growth in our emerging electric vehicle charging infrastructure business, improved access to client sites and strengthened client demand for energy efficient solutions.
Segment operating income returned to profitability and generated an operating profit margin of 12.8%.
We ended the fourth quarter with $62.8 million in cash and cash equivalents, compared to $394.2 million with total debt of $1.06 billion as of October 31, 2021.
Our total debt to pro forma adjusted EBITDA, including standby letters of credit was 1.9 times at the end of the fourth quarter of fiscal 2021.
As for our dividends, I am pleased to report the Board approved a 2.6% increase in our quarterly dividend to $19.5 to be paid out in February.
As Scott mentioned, our guidance for full year fiscal 2022 adjusted income from continuing operations is a range of $3.30 to $3.55 per diluted share.
Please note that our adjusted earnings guidance excludes approximately $72 million in Elevate related expenses that are planned in fiscal 2022.
We expect that fiscal 2022 tax rate to be approximately 30% excluding any discrete items.
As a reminder, each workday represents approximately $7 million of labor expense.
Capital expenditures for fiscal 2022 are expected to be approximately $54 million, including $8 million related to Elevate investments.
We forecast depreciation to be approximately $50 million for the year.
This will improve the productivity of our frontline workforce and create digital connections with our clients and our teammates and will drive profitable growth, will accelerate organic revenue growth rates by close to 50% with sustainable adjusted EBITDA margins almost double where we started in 2015, while building on our significant cash flow.
To fund our acquisition strategy during 2020 vision, we upsized our credit facility from $800 million to $1.6 billion.
We also consistently increased our dividend for over 55 years.
Our journey started with a 3.8% adjusted EBITDA margin.
By 2019, our adjusted EBITDA margin expanded by 140 basis points to 5.2%.
Revenue grew by 23% to $6.5 billion and adjusted earnings per share grew 27%, reaching $2.05 per share.
We acted quickly and decisively, rapidly building and deploying new capabilities and mobilizing our teams to lead our clients through the unpredictable shutdowns and reopenings we've all experienced over the past 20 months.
These actions led to bottom line profitability beyond expectation, driving our pre-COVID adjusted EBITDA margin baseline from 5% up to 7.3% in 2021, while generating cumulative COVID-related revenues of $600 million over 2020 and 2021.
Our world has fundamentally changed over the past 20 months.
We have unrivaled competitive advantage anchored in our market leadership across all end markets and industries we serve, unparalleled reach with a large distributed network of people and branch offices to serve our clients across the US and UK, a unique portfolio of services spanning janitorial, engineering, parking, technical solutions and aviation services, a trusted reputation that we have earned over the last 110 years of long-lasting client relationship and a strong balance sheet that we will use strategically and opportunistically as expansion possibilities arise.
The total addressable market although very large at $250 billion is highly fragmented.
The $1 trillion bipartisan infrastructure bill that just passed will open doors for us.
In fact, it allocates $7.5 billion that could be used to construct EV charging stations.
We expect both higher education and K-12 schools to continue to invest in disinfection programs, while also focusing on indoor air quality.
However, our exposure to airports and not just airlines insulated us against the more severe impact as flight volumes dropped almost 90% during the peak.
Over the last few years, we've evolved from 45% airport clients and 55% airline clients to 55% airport clients and 45% airline clients as airports are less impacted by fluctuating passenger volume.
Estimates show that 1 billion square feet of net new US distribution warehouse space is needed to support e-commerce growth due to consumer demands.
This represents more than 100% growth in these types of facilities.
The accelerated growth of our technology clients with their expanded office footprint is best served by B&I and the branch network with roughly $300 million in annual revenue moving over.
M&D will maintain our large manufacturing clients and add distribution clients with roughly $400 million in annual revenue moving over.
We will build stronger HR capabilities by enhancing our HR shared services center that provides team members with support in HR related information 24/7, while we continue to evolve our broader HR capabilities.
Melanie is a visionary technology leader with more than 20 years of experience across diverse industries, including gaming, commercial real estate, manufacturing, healthcare and aviation.
The substantial increase in demand for disinfecting services combined with our team's continued strong operational execution and drive for labor efficiencies contributed to record adjusted EBITDA margins exceeding 7% in fiscal 2021.
This represents a more than 200 basis point improvement versus pre-COVID adjusted EBITDA margins in fiscal 2019.
While we anticipate an easing of these tailwinds as we emerge from the pandemic, we are confident that we can retain approximately 50 basis points to 70 basis points of uplift over the long-term as we expect to maintain a portion of both the disinfection related revenue and profitability along with a higher baseline level of labor efficiency.
As we build upon the improved positioning gained over the past 18 months, we are guiding to an adjusted EBITDA margin within a range of 6.2% to 6.6%.
This represents a meaningful improvement over our baseline pre-pandemic adjusted EBITDA margin of 5.2% reported in fiscal 2019, but lower than fiscal 2021 as the pandemic tailwinds ease and our business begins to normalize.
Our Elevate strategy includes a series of discrete transformational investments that total between $150 million to $175 million.
By design, the Elevate plan is front-end loaded as we plan to spend approximately $80 million in fiscal 2022 or by approximately $45 million in fiscal '23 and approximately $15 million in each of the following two years.
Of the $80 million planned in fiscal 2022, approximately $72 million will be a discrete expense and will be reported as items impacting comparability and as such will not be included in adjusted earnings per share guidance of $3.30 to $3.55.
The balance of approximately $8 million will be included in capital expenditures.
About 30% of the investments will be allocated toward workforce management and the investment in our people.
The remaining 20% will be used to fuel our organic growth initiatives and our go-to-market strategies, including investments in centralized platforms to support capabilities such as hyper sales targeting, price optimization and strategic account management.
Our goal is for Elevate to accelerate our organic revenue growth rate to the mid-single digit range, up approximately 50% versus our previous growth rate with potential upside from additional strategic acquisitions.
As revenue growth accelerates, we also anticipate a corresponding and gradual improvement to our adjusted EBITDA margins of approximately 20 basis points annually starting in fiscal 2023.
The related investments are expected to generate $110 million to $130 million in incremental adjusted EBITDA on a run rate basis by fiscal 2025, driving a projected internal rate of return of 28%.
To put this in perspective, at the conclusion of Elevate in fiscal 2025, we envision ABM will generate annual revenue of approximately $9 billion with a sustainable adjusted EBITDA margin of 7%, representing a significant improvement from our baseline level of $7 billion in revenue with a normalized adjusted EBITDA margin below 6%.
We are also targeting annualized free cash flow at a run rate of approximately $400 million by fiscal 2025.
Our goal is to be a roughly $9 billion business with [Technical Issues] sustainable adjusted EBITDA margins by the end of 2025.
From a growth perspective, our investments will drive organic growth rates, almost 50% higher than -- approaching 4% annually.
When factoring in our M&A strategy, we are targeting an overall compounded annual growth rate of over 10%.
The focus on the client experience through investments in customer-facing technology and innovation and a new retention strategy aim to improve our client retention rates to between 92% and 94%.

Summary:
Fourth quarter revenue increased 14.2% to $1.7 billion, primarily driven by one month of contribution from the acquisition Able Services, continued client demand for disinfection services and a generally improving economic environment.
GAAP income from continuing operations in the fourth quarter was $34.3 million or $0.50 per diluted share, compared to $53.1 million or $0.78 per diluted share in the same period last year.
On an adjusted basis, fourth quarter income from continuing operations grew 25% to $58.2 million or $0.85 per diluted share compared to $46.7 million or $0.69 per diluted share in the fourth quarter of last year.
As for our dividends, I am pleased to report the Board approved a 2.6% increase in our quarterly dividend to $19.5 to be paid out in February.