Diesel-electric locomotives have been around in their current form since before World War II. Following the war, during which every available piece of railroad rolling stock was pressed into service, the railroads got back to the business of replacing their beloved (at least to enthusiasts) but comparatively inefficient steam fleets with diesels. Over the years, there have been steady improvements in horsepower, tractive effort, fuel economy, and reduced emissions. Now, recent developments in technology have brought the diesel-electric locomotive to a new level of productivity.
Such developments started in the early 1990s, when the Burlington Northern sparked a major motive power evolution by acquiring 350 EMD road locomotives fitted with a.c. traction motors. “Two for three” and “three for five” were a chief mechanical officer’s most-often-used way to describe how fewer units could haul the same amount of tonnage compared to a d.c.-traction locomotive. A.c. traction, with its fewer moving parts, also produced time savings on the shop floor, thereby increasing utilization.
Distributed power closely followed a.c. traction. The ability to strategically place remotely controlled locomotives throughout a consist as well as at the rear for pusher duty has enabled the railroads to be more productive by doing things like operating longer, heavier trains and eliminating helper districts.
Microprocessor control of such systems as engine management and traction (wheelslip) has further advanced locomotive efficiency. Computing power has grown to the point where every major locomotive subsystem is managed in some form by a microprocessor.
The genset locomotive—two or three microprocessor-controlled, modular prime mover/traction alternator assemblies in one unit—has become the 21st century equivalent of a.c. traction. Pioneered by National Railway Equipment Company (p. 18) and Union Pacific (and produced by Wabtec, RJ Corman RailPower, Brookville Equipment Corp., Progress Rail/EMD, and Railserve), a new generation of fuel efficient, low-emission, highly productive switchers and road units is changing how railroads buy and use motive power. Combine all these developments with technologies like AESS (automatic engine start-stop systems), engine preheating systems, and engineer-assist software, and the diesel-electric locomotive is arguably the most efficient, productive form of freight transportation ever devised.
A changing market
The locomotive market is moving in a new direction, according to “The Changing Locomotive Marketplace: Implications for Future Demand,” a reported presented by Oliver Wyman’s Jeffery P. Elliott at Railroad Financial Corp.’s Railroad Equipment Finance 2011 Conference in Palm Springs earlier this year.
“As the rail industry emerges from the economic downturn, what will drive new locomotive demand? Traditionally, North American locomotive purchases are closely related to growth in gross ton-miles,” says Elliott. “However, several issues could change the slope of the demand curve for the next few years. Among these are step-change improvements in operational integrity, network velocity and fluidity, and service reliability; rail traffic volume and pattern changes due to supply chain reconfiguration and modal issues; rail’s emergence as a ‘green’ alternative; new government regulations and their associated capital investment requirements (such as Positive Train Control); the complexity and cost of complying with U.S. Environmental Protection Agency Tier 4 diesel engine emissions regulations; and new fuel price fundamentals.”
“As customers redefine supply chains, ‘green’ has become a key differentiator, along with cost and security,” says Elliott. “Improvements in rail reliability and service have been noticed, and rail is getting a second look from customers that in the past would not consider it as an alternative. As well, there have been recent and continuing share gains from trucks. Bankruptcies and capacity reductions have impacted coverage and driven conversion to intermodal. Customers who diverted to intermodal to save money now like the service. Regulatory changes (for example, truck driver Hours of Service rules) are increasing the cost and complexity of truck solutions. Fuel price increases have enabled effective rail competition on shorter hauls.”
The need for lower emissions and better fuel economy is driving locomotive technology development. “Gensets have shown impressive performance in road switcher service,” Elliott says. “They offer significantly better fuel economy and tractive effort than conventional switchers [and] lower emissions, allowing railroads to access environmental grants and programs to mitigate acquisition costs. Outside of non-attainment areas or where government grants have been provided, genset economics have been more problematic, and the savings have not produced attractive returns. However, since returns are a function of fuel prices, higher fuel prices may improve the economics.”
Lowering locomotive life cycle cost has become the new standard for railroads, and Elliott points to several new technological developments, among which are special purpose locomotives. BNSF, for example, is testing GE’s ES44C4 locomotive, a six-axle unit with four traction motors. This locomotive “has a lower initial cost relative to current a.c. locomotives (comparable to a d.c. locomotive),” he says. It offers lower maintenance costs, high speed performance comparable to a six-axle a.c. locomotive, and lower tractive effort at lower speeds—a potentially attractive alternative for intermodal.”
Capturing and storing braking energy could be used to start heavier trains or to boost trains over a ruling grade and reduce the need for helpers. As well, builders have been incorporating improved and advanced fuel management into locomotive designs to further reduce fuel consumption. “Most of this work is being done with lower-horsepower units than what Class I’s are currently purchasing,” Elliott says.
The Tier 4 challenge
The EPA’s Tier 4 requirements “are intended to require aftertreatment for NOx and PM,” according to EMD’s David Brann. “Aftertreatment involves processing the exhaust after it leaves the engine to reduce emissions. Internal engine changes can minimize engine-out emissions, and reduce the operational complexity and cost of aftertreatment. Among these are tuning of the engine for NOx reduction, fuel injector refinements, and, possibly, exhaust gas recirculation. Aftertreatment means include SCR (Selective Catalytic Reduction) for NOx, and DOC (Selective Catalytic Reduction) and DPF (Diesel Particulate Filter) for PM.”
The EPA “has recognized that some things were not cost-effective on existing locomotives,” Brann says. “For example, major surgery on a locomotive, like a split cooling system to add low-temperature charge air cooling, or retrofitting of aftertreatment systems to older locomotives. Manufacturers have worked closely with EPA to describe what was possible with existing locomotive configurations.”
Tier 4 locomotives will be more expensive, Brann says. “There’s more hardware, plus the platinum-group metals in catalysts and PM filters. Aftertreatment devices may cost as much as or more than the engine itself. There will be higher operating costs stemming from additional fluids (for example, aqueous urea if SCR is used) and maintenance and replacement of aftertreatment components. Then, there are real packaging concerns. How do you fit all this stuff in a locomotive? Overhauls will be more expensive. Higher new locomotive and emissions kit development costs will have to be passed on to the customer.”
Hotstart aids Montana Rail Link
Under its National Clean Diesel Funding Assistance Program, the EPA has funded several locomotive idle reduction projects that use Hotstart APUs (Auxiliary Power Units). One current initiative involves the Missoula (Montana) Metropolitan Planning Organization, the Missoula City/Missoula County Health Department Air Quality Division, and Montana Rail Link. The project includes installation of APUs on 34 older locomotives that currently have no idle reduction technology and thus might idle 24 hours per day (on weekends) for 10 months of the year in MRL’s Missoula switchyards, “contributing unnecessarily to diesel use and emissions, and contributing significantly to an already-impaired local airshed,” according to the grant application. “Installation of the APUs would eliminate the need to idle unnecessarily during cold weather, improving Missoula’s airshed, and decreasing emissions-associated health risks.”
The Hotstart APUs are an EPA-verified idle reduction technology that reduces the need to idle the main diesel engine when temperatures fall below 40 degrees F, a condition that occurs year-round in Montana. Use of the APUs in place of the idling the main engines are expected to result in an annual reduction of 5,423 tons of emissions and save 471,676 gallons of diesel annually. Total project reductions over the expected life of the APUs (25,000 hours, or a minimum of 10.2 years) are 55,390 tons of emissions and 4.82 million gallons of diesel fuel. A video demonstration is available at www.hotstart.com.
Optimizing MU power
Improving productivity can also depend upon operating a locomotive or set of locomotives optimally, and a host of systems to assist locomotive engineers has been developed. “Freight trains are typically dispatched with enough locomotives in consist to make the ‘ruling grade’—often resulting in surplus power for most of the trip, with trailing locomotives operating at the same throttle setting as the lead unit,” notes EMD. The EMD SmartConsist™ Fuel Management System “automatically sets each locomotive to its optimal throttle position, improving fuel economy, cutting emissions, and reducing noise in the lead locomotive. SmartConsist™ is fully integrated within the EM2000™ locomotive control system and its operation is transparent to the crew. The engineer simply selects the desired throttle notch in the lead locomotive, and the most fuel efficient power settings are activated for each unit. SmartConsist™ continuously monitors and sets the most fuel efficient combinations to achieve the required power and tractive effort. SmartConsist™ “is suitable for both two- and three-unit locomotive consists, without unit isolation,” says EMD.
GE’s Trip Optimizer fuel management system is described as “an advanced energy management system that optimizes fuel consumption based on a specific train’s makeup and route.” It uses GPS, a digital track database, and advanced track algorithms that automatically learn the train’s characteristics throughout the trip. It evaluates train length, weight, grade, track conditions, weather, and locomotive performance “to calculate the most efficient way of running the train while maintaining smooth train handling. It calculates a fuel-optimal speed profile for the trip and then automatically controls the throttle to maintain that planned speed. Train crews retain responsibility for safe operation of the train and can engage or disengage the system at any time.” Trip Optimizer can be deployed on Evolution Series locomotives as a turnkey system, and can be combined with GE LOCOTROL® Distributed Power.
Invensys Rail Corp.’s LFO™ (Locomotive Fuel Optimizer) optimizes fuel economy and train handling in multiple-unit locomotive consists by automatically making individual throttle adjustments among the locomotives based on total power demand. It minimizes middle-notch (N3-N7) fuel inefficiencies without compromising total power, adhesion, or safety, Invensys says. LFO has delivered average fuel savings of 3% to 4% in tests. The system is compatible with all EMD and GE locomotive models, features automatic calibration, and will work seamlessly with dynamic brakes and PTC.
Changing out a piece of common, standard equipment like a locomotive starting battery can improve productivity. The Element™ SLS line of valve regulated locomotive starting batteries from GNB Industrial Power (a division of Exide Technologies) “utilizes proven Absolyte® VRLA technology to create the industry’s first low-maintenance railway diesel starting battery,” according to Sid Bakker, president of TPSC, distributor for GNB products. “Unlike the standard flooded battery where electrolyte is fully mobile (spillable), the electrolyte in the SLS battery is absorbed in glass mat separators. This design facilitates the oxygen recombination with virtually no loss of liquid, so no maintenance watering is required. Also, the batteries are non-spillable, eliminating damage to equipment, greatly reducing environmental concerns, and increasing personnel safety. It’s fully recyclable, and requires no gassing with proper use. This battery improves productivity through increased cold cranking amps and a longer maintenance cycle, compared to a flooded battery.”