Greg C. Gantt
President and Chief Executive Officer at Old Dominion Freight Line
Good morning, and welcome to our fourth quarter conference call. With me on the call today is Adam Satterfield, our CFO. After some brief remarks, we'll be glad to take your questions.
Old Dominion finished 2021 with outstanding fourth quarter financial performance that resulted in new Company records for annual revenue and profitability. The fourth quarter of 2021 was our fourth straight quarter with double-digit revenue growth and the sixth straight quarter of double-digit growth in earnings per diluted share. We are encouraged by the momentum in our business and believe that we are uniquely positioned to win additional market share in 2022. We can do this by continuing to execute on the same strategic plan that has driven our history of long-term profitable growth. This strategy is centered on our ability to deliver a value proposition of superior service at a fair price to our customers.
The OD family of employees work through every challenge thrown its way in 2021, and continue to deliver best-in-class service, while skillfully managing the 19.4% growth in our LTL shipments per day for the full year. I can assure you that delivering on time without damage is a significant accomplishment with this type of volume growth. That is why I'm so proud that in 2021, we once again earned the MASTIO Quality Award, which recognizes us as the national number one LTL carrier for the 12th straight year, providing superior service not only allows us to win market share, it also supports our long-term pricing strategy.
We have consistently focused on improving our yields at the individual account level to both offset our cost inflation and support further investment in our business. This approach has helped strengthen our financial position over time and allow us to do something that others in our industry have not consistently invest in new capacity.
We have historically invested 10% to 15% of our revenue in capital expenditures each year, and we expect to spend approximately $825 million this year. We believe consistent and long-term investments in capacity are valued by customers, as an integral component of quality service and these investments are also necessary to support our ongoing market share initiatives.
We simply never want our service center network to be a limiting factor to growth, which is why we have spent over $1.8 billion over the past 10 years to expand our service center capacity across the nation. We currently have approximately 15% to 20% of spare capacity in our network. Although, our 2022 capital expenditure plan includes another $300 million to further expand our service center capacity to stay ahead of our anticipated growth curve.
There are, of course, two other ingredients in the capacity equation, our fleet and our people. We intend to spend $485 million for new tractors and trailers this year. We would frankly like to spend more, but we have been limited by several suppliers that are facing manufacturing challenges. We are fortunate -- we're fortunate to enter the pandemic with one of the youngest fleets in our industry, and as a result, we can continue to use existing equipment that otherwise would have been replaced this year.
This strategy may continue to cost us a little more in maintenance and repair costs as it did in 2021, but we believe our current fleet and these additions will be sufficient to accommodate our expected growth. As we have done in recent quarters, we also expect to continue to utilize purchase transportation to supplement the capacity of our people and our equipment.
The final ingredient and the most important piece of our strategic plan is the investment that we continuously make in our people. The OD family of employees grew by 20% in 2021, which including adding over 1,700 drivers in a challenging labor market. We expect that 2022 will be another big recruiting year for OD. While the labor market remains challenging, we are confident in our ability to add to our team, due to our outstanding company culture. In addition, we offer a rewarding pay and benefits package, and soon expect to make company record discretionary contribution to our employees 401(K) retirement plan.
Our long-term strategic plan is straightforward. Difficult for others to successfully replicate and builds on itself year-after-year. Our success over the years has proven the flywheel effect of our strategic plan, and we believe it will spin even faster in 2022. We are encouraged by the opportunities ahead, and we are confident that the disciplined execution of this strategic plan will produce further profitable growth and increase shareholder value.
Thank you for joining us this morning, and now Adam will discuss our fourth quarter financial results in greater detail.