The decreases in tonnage per day for the three and nine months ended September 30, 2024, compared to the same prior-year periods, are primarily related to the soft market environment related to prolonged weakness in industrial production, which has resulted in lower average weight per shipment levels as well as lower daily shipment levels. Total shipments, which decreased 0.7% and 4.0% for the three- and nine-month periods ended September 30, 2024, respectively, on a per-day basis, were impacted by changes in the Asset-Based business mix as well as the softer freight environment.
The increases in total billed revenue per hundredweight, including fuel surcharges, for the three and nine months ended, compared to the same periods of 2023, were also driven by lower weight per shipment, which generally increases revenue per hundredweight, offset partially by lower fuel surcharge revenue associated with lower fuel prices, compared to the prior-year periods. The pricing environment for LTL shipments continues to be rational. Excluding the impact of fuel surcharges, the percentage increase in billed revenue per hundredweight on our traditional LTL-rated freight was in the high single-digits and low-double digits, respectively, for the three and nine months ended September 30, 2024, compared to the same periods of 2023. Prices on accounts subject to deferred pricing agreements and annually negotiated contracts which were renewed during the three and nine months ended September 30, 2024, increased approximately 4.6% and 5.0%, respectively, compared to the same periods of 2023. The Asset-Based segment implemented a general rate increase on its LTL base rate tariffs of 5.9% effective on September 9, 2024, although the rate changes vary by lane and shipment characteristics.
The Asset-Based segment’s average nominal fuel surcharge rate decreased by approximately 5 percentage points and 3 percentage points in the three- and nine-month periods ended September 30, 2024, compared to the same periods of 2023. During periods of changing diesel fuel prices, the fuel surcharge and associated direct diesel fuel costs also vary by differing degrees. Depending upon the rates of these changes and the impact on costs in other fuel- and energy-related areas, operating margins could be impacted. Whether fuel prices fluctuate or remain constant, operating results may be adversely affected if competitive pressures limit our ability to recover fuel surcharges. In periods of declining fuel prices, fuel surcharge percentages also decrease, which negatively impacts the total billed revenue per hundredweight measure and, consequently, revenues. The revenue decline may be disproportionate to the change in our fuel costs. The segment’s operating results will continue to be impacted by further changes in fuel prices and related fuel surcharges.
Asset-Based Operating Income
The Asset-Based segment generated operating income of $64.0 million and $190.3 million for the three and nine months ended September 30, 2024, respectively, compared to $74.8 million and $165.6 million, respectively, for the same periods of 2023. Compared to the prior-year periods, the Asset-Based segment’s operating ratio deteriorated by 1.1 percentage points for the three months ended September 30, 2024, primarily reflecting the decline in revenue, and improved 1.4 percentage points for the nine months ended September 30, 2024, primarily reflecting decreased operating expenses as a result of cost control efforts to reduce utilization of outside resources and optimize internal resources, and pausing the freight handling pilot test program at ABF Freight during third quarter 2023, as further discussed in the following paragraphs.
Asset-Based Operating Expenses
Labor costs, which are reported in operating expenses as salaries, wages, and benefits, amounted to 50.5% and 50.4% of Asset-Based segment revenues for the three- and nine-month periods ended September 30, 2024, respectively, compared to 48.2% and 48.0%, respectively, for the same periods of 2023. Salaries, wages, and benefits increased $0.9 million and $18.4 million for the three and nine months ended September 30, 2024, respectively, compared to the same periods of 2023, due to contract rate increases under the 2023 ABF NMFA, as previously discussed in the Asset-Based Revenues section. On July 1, 2023, wage rates increased 13.1% and the health, welfare and benefits rate increased 4.0% on August 1, 2023, for a blended increase of 9.1% during the third quarter 2023. On July 1, 2024, wages increased another 2.5% and benefits increased 2.9% on August 1, 2024, for a blended increase of 2.7% in third quarter 2024. The increases in salaries, wages, and benefits from the union contract rates were offset in part, by improved productivity, as measured by shipments per DSY hour, a decrease in headcount to align with lower shipment levels, and by lower utilization of purchased transportation as discussed later in this section.
The Asset-Based segment manages costs with shipment levels; however, a number of factors impact DSY productivity, including the effect of freight profile and mix changes, utilization of local delivery agents, and efficiency of personnel. Shipments per DSY hour improved for the first nine months of 2024, compared to the same period of 2023, primarily due