C. Smith
Analyst · Stephens
Great. Thank you, David, and good morning. In the 2015 fourth quarter, marine transportation segment revenue declined 7% and operating income declined 16% as compared with the 2014 fourth quarter. The decline in revenue in the fourth quarter as compared to the prior year was primarily due to a 41% decline in the average cost of marine diesel fuel, an increase in inland marine delay days and an increase in available spot market days for certain offshore marine equipment. The marine transportation segment's operating margin was 22% compared with 24.3% for the 2014 fourth quarter. The inland sector contributed approximately 2/3 of marine transportation revenue, with the coastal sector contributing 1/3.
Inland marine weather presented several challenges during the quarter. In the first half of the quarter, we experienced flooding and strong crosscurrents at certain river crossings on the gulf intercoastal waterway as well as the closure of 2 major locks, which were reopened in mid-November.
Late in the quarter, high water on the Mississippi River system led to tow restrictions and the closure of the river near St. Louis during the final 3 days of the quarter. These conditions contributed to a 15% year-over-year increase in delay days. High water on the Mississippi River system is continuing into this quarter and, in fact, still impacting the industry in the fourth quarter. Despite these challenges, the inland sector generated an operating margin in the mid-20% range for the quarter.
In the coastal sector, the number of contract renewals was limited, but pricing on those that did renew were flat to up slightly. As David and Joe each mentioned, we continue to have equipment move into the spot market as customers are reluctant to agree to term contracts and they are increasingly confident that sufficient spot equipment will be available to handle their needs. We have been successful in keeping spot equipment employed at high levels of utilization, which for the quarter averaged over 90%. Nevertheless, even at high levels of utilization, unutilized days for equipment in the spot market have a negative financial impact relative to the contribution provided under time charter contracts. Additionally, voyage and positioning costs incurred in order to take advantage of spot opportunities can impact profitability. The fourth quarter operating margin for the coastal sector was in the mid-teens.
Over the course of 2015, we took delivery of 36 new tank barges, and when combined with the 6 pressure barges purchased in the first quarter, increased capacity by approximately 590,000 barrels. The number of barges we retired, including returned charter barges, totaled 26, removing approximately 380,000 barrels of capacity. We also transferred 2 coastal tank barges that were working inland back into the coastal fleet. The net result was an addition of 14 tank barges to our inland tank barge fleet and approximately 165,000 barrels of additional capacity.
In the 2016 first quarter, we expect to take delivery of 3 30,000 barrel inland tank barges, with a total capacity of approximately 90,000 barrels. We currently have no plans to build any tank barges beyond the first quarter, although we will continue to evaluate our needs throughout the year. We expect to retire or return 30 barges over the course of the year and in 2016, with approximately 17.6 million barrels of capacity, a reduction of approximately 365,000 barrels from the end of 2015. In addition to the inland retirements, we retired a 38-year-old ocean-going dry-bulk ATB on the last day of 2015. We expect this will have an approximate $1 million negative year-over-year earnings effect on 2016.
In the coastwise transportation sector, with respect to our new vessels, construction of our 4 coastal articulated tank barge and tugboat units continues to progress along the schedule we last presented. The first of our 4 planned ATBs, a 185,000-barrel, 10,000-horsepower ATB, entered service late in 2015. Our second new coastal vessel, also a 185,000-barrel ATB, is likely to deliver in mid-2016. Both 185,000-barrel ATBs are under multiyear customer contracts. We continue to expect delivery of the first 155,000-barrel ATB in late 2016, and our second 155,000-barrel ATB is scheduled to deliver by mid-second quarter 2017.
Additionally, we are building a coastal chemical barge that we expect to enter service in early 2017 as a replacement for equipment expected to retire simultaneously. The coastal equipment requirements that we expect to impact our 2016 results include a 150,000-barrel coastal barge that we retired at the end of 2015 and an 80,000-barrel ATB that we expect to retire in the first quarter of this year.
You may notice that our total capital expenditures for 2015 were $343 million, approximately $15 million higher than we had anticipated in our last earnings call. This was the result of progress payments on our new coastal units that we incurred in December 2015, a month earlier than anticipated.
Moving on to our diesel engine services segment. Revenue for the 2015 fourth quarter declined 65% from the 2014 fourth quarter, and we had a small operating loss for the segment. The segment's operating margin was a negative 0.6% compared with 5.4% for the 2014 fourth quarter. The marine and power generation operations contributed approximately 50% of the diesel engine services revenue in the fourth quarter, with an operating margin in the low double digits. Our land-based operations contributed roughly half of the diesel engine services segment's revenue in the fourth quarter, with a negative operating margin in the low to mid-teens. During the quarter, we recognized some costs related to consolidating our manufacturing facilities into a single location and to inventory adjustments, which led to a more significant operating loss. Also modestly impacting results was our finalization of the previously-announced sale of UE Compression LLC early in the 2015 fourth [ph] quarter.
On the corporate side of things, our cash flow remained strong during the quarter, which helped fund our marine equipment construction plans and $39 million of treasury stock purchases during the quarter. Any future decision to repurchase stock will be based on a number of factors, including the stock price, our long-term earnings and cash flow forecasts as well as alternative opportunities available to deploy capital, including acquisitions. On -- our 2016 capital spending guidance range is $220 million to $240 million, including completion of the 3-in-1 tank barges and 1-in-1 towboat to be delivered in 2016 and approximately $95 million in progress payments on new coastal equipment, including 1 185,000-barrel coastal ATB, 2 155,000-barrel coastal ATBs, 2 4,900-horsepower coastal tugboats and a new coastal petrochemical tank barge. The balance of $124 million to $144 million is primarily for capital upgrades and improvements to existing inland and coastal marine equipment and facilities as well as diesel engine services facilities. Total debt as of December 31, 2015, was $779 million, a $31.6 million decrease from September 30, 2015. Our debt-to-cap ratio at December 31, 2015, was 25.5% compared with 24% as of December 31, 2014. As of today, our debt stands at $734 million.
I'll now turn the call back over to David.