Double-stack rail refers to a form of freight transportation where two layers or "stacks" of intermodal containers are placed one on top of the other on specially designed rail cars. This method of transportation efficiently maximizes the carrying capacity of each rail car and is particularly advantageous for long-haul freight transportation. The rail cars used for double-stacking have a depressed center, which allows the containers to be stacked without exceeding the height restrictions imposed by tunnels and bridges on the rail network.
Adopting the double-stack rail system has led to significant economic and environmental benefits. By doubling the cargo capacity on a single train, operators can move the same amount of goods with fewer trips, resulting in cost savings and reduced fuel consumption. Furthermore, this translates to lower greenhouse gas emissions and reduced congestion on rail networks. While the initial investment in infrastructure, such as specialized rail cars and the modification of existing structures to accommodate taller trains, might be substantial, the long-term efficiencies gained make double-stack rail a preferred choice for many rail operators worldwide.
In 1984, container trains began breaking through cost, capacity and service barriers by using specially engineered rail cars that could carry two tiers of containers instead of one -- significantly reducing the locomotive power, track capacity and train crews required by conventional intermodal trains to move a comparable payload.
The double-stack rail car's unique design also significantly reduced damage in transit, and provided greater cargo security by cradling the lower containers so their doors cannot be opened. And a succession of large, new domestic container sizes was introduced to further enhance shipping productivity for customers.
And the innovations continued 20 years later, according to Tom Shurstad, president of Pacer Stacktrain, which was part of Pacer International. Pacer, in 2004 the largest wholesale provider of double-stack rail service in North America, acquired the pioneering double-stack rail network in 1999 from global ocean carrier APL, which had developed and introduced the concept.
Pacer Stacktrain managed a large fleet of advance-engineered rail cars and containers to provide transcontinental double-stack service, with underlying transport provided under contract with leading railroads. The result was an integrated North American distribution network supported by multiple railroads, connecting virtually all major commercial centers and offering more than 500 weekly departures.
"Double-stack innovation began with equipment technology," said Shurstad. "Now industry focus has evolved to an entirely different area of innovation -- to improving global supply-chain efficiency through better process, information and collaboration," he said. "For example, we have opened new Pacer Stacktrain service routes for customers and pioneered a cross-border intermodal product that streamlines the movement of general merchandise between the United States and Mexico. We consider U.S.-Mexico trade a particular focus area for future growth."
According to Kevin Ohme, manager of Crossborder Intermodal for C.H. Robinson Worldwide, one of North America's largest third-party logistics companies, Pacer's recently introduced Mexico services illustrate the company's commitment to innovation. He cited PacerMex NonStop, an expedited service designed to move consumer goods between Mexico and points in the U.S. Midwest and Northeast. "PacerMex NonStop provides us a reliable alternative to existing services. We find that the program can help customers reap additional value by avoiding delays and the handling costs at the border," Ohme said. "Because inspections occur at the final destination, we bypass the congestion in Laredo."
Equipment leadership has continued, also. Today, Pacer Stacktrain operates the largest and most diversified domestic container fleet in North America. The company has significantly increased the size of its equipment fleet since acquiring the double-stack rail network in 1999, and has been a leader in the development of high-capacity, 53-foot steel containers with 110-inch-high doors. By introducing newer, lighter-weight steel containers with reengineered, damage-resistant walls that increase reliability and further reduce cargo damage, Pacer is facilitating more efficient and cost effective cargo handling for customers.
"As a result of this continuing drive for improved service," said Shurstad, "today's double-stack rail network offers unprecedented value through better end-to-end transit reliability, shipment visibility, fuel efficiency, and improved cargo security."
Double-stack rail service proved to be pivotal to the growth of containerized intermodal freight in North America. The total volume of intermodal shipments has grown three-fold since the mid-1980s, according to the Intermodal Association of North America.
For freight intermediaries -- the intermodal marketing companies, ocean carriers, and other third parties that market end-to-end transportation services to businesses that ship product worldwide -- introduction of the double-stack train revolutionized their business.
"The double-stack alternative was more cost-effective than the basic container-on-flat car, piggyback, or truck for cross-country moves," according to Ron Lefcourt, president of Alliance Shippers, one of North America's leading intermodal marketing companies. "Double-stack service significantly reduced cargo damage and claims," said Lefcourt. "And that helped us sell intermodal services to the skeptics."
To illustrate the continuing attractiveness of the double-stack mode for both international and domestic freight moving throughout North America, Pacer Stacktrain says it now carries more than one million containers per year. "The company accounts for approximately 20 percent of all international and domestic container moves in North America," Shurstad said. "Overall, the double-stack market has grown more than 100-fold since 1984, and now accounts for about 70 percent of all intermodal shipments."
Shurstad said much of the growth of Pacer Stacktrain's volumes -- and the growth experienced by other providers -- has been the result of conversion of freight from long-haul trucks to intermodal transport. "We expect to see this growth continue," he said, "reflecting both modal conversions and growth of the total intermodal market."
While always deflecting credit to the many contributors who enabled the introduction of Stacktrain rail service, Pacer International's chief executive officer, Don Orris, is widely considered the "Father of Stacktrain Service" for his role in the early 1980s, as head of APL's intermodal department, in sponsoring the development and implementation of the Stacktrain network.
And about 50 of Orris' colleagues who worked with him in 1984 at APL are still associated with Pacer Stacktrain today. Tom Shurstad is one of them.
"Many intermodal veterans still remember the illustrated news stories that ran in those early days after Don Orris decided to demonstrate to customers how double-stack technology could reduce in-transit damage for fragile merchandise such as electronics," recalls Shurstad. "He had us load up a container with a dinner table, all set with crystal, china and silverware, and rail it across the country. Everything arrived intact, and Don made his point about the Stacktrain's 'Smooth Move!'
"We all take a lot of pride in the contributions that double-stack technology has brought to our industry," Shurstad said. "For our part, Pacer Stacktrain has taken seriously its commitment to provide continued leadership, innovation and investment. We will continue to expand the service network, systematically improve quality, upgrade equipment, increase the total fleet size, and introduce innovative services designed to keep freight flowing -- which is the chief concern of many customers today."
He noted that the company also stations intermodal experts at rail terminals throughout its network to expedite its customers' shipments.