For more than a decade, diesel engine technology enhancements have helped railroads significantly cut fuel consumption and reduce emissions. Engine manufacturers have overhauled their products to meet Tier 1, then Tier 2, then Tier 3 emission standards as regulated by the U.S. Environmental Protection Agency. And now, those manufacturers are facing one of their greatest challenges yet: creating an engine that slashes particulate matter by 70 percent and nitrogen oxide (NOx) emissions by 76 percent from the current Tier 3 emission levels. The Tier 4 regulations will take effect Jan. 1, 2015.

The pending regulations aren’t the only thing keeping manufacturers on their toes. Many railroads are exploring the possibility of transitioning from diesel- to natural gas-fueled locomotives, and need engines that can run on both. They also continue to seek options for remote diagnostic capabilities. To that end, many suppliers are launching new products and tweaking existing ones to address regulatory issues and help railroads achieve their locomotive-efficiency needs.

Since introducing the Tier 2-compliant Evolution® Series locomotive in 2005, GE Transportation has upgraded the platform to meet Tier 3 emissions regulations and provide increased fuel efficiency. Now, the company is testing the Evolution Series Tier 4 locomotive.

“We haven’t changed the base platform, so we’re not really changing the engine itself,” says Tina Donikowski, GE’s vice president of Locomotive, Marine and Stationary Power & Drill.

The units will meet Tier 4 regulations without the use of aftertreatment, a system of filters, converters and chemicals that work like a catalytic converter in an automobile, says Edward Hall, engineering leader for GE’s engine development group. Instead, GE designed the engine using a combination of exhaust gas recirculation, air handling and high-pressure fuel system advancements, according to the company.

Two units have been in testing since last year and recently were sent — along with three other locomotives fresh off the production line — to Union Pacific Railroad, which will test them through summer’s end, says Heavy Haul Product Leader Len Baran. By year’s end, GE plans to send 20 pre-production Evolution Series Tier 4 locomotives to BNSF Railway Co. for another two years of testing, says Donikowski.

In the meantime, GE is developing the NextFuel™ Natural Gas Retrofit Kit, which is designed to enable existing Evolution Series locomotives to operate with dual-fuel capabilities. A retrofitted control system could automatically recognize if natural gas or diesel is being pumped into the engine, which then would be tuned accordingly, Baran says.

“With natural gas, it’s not the mechanics that are challenging; it’s the software and control strategy — what to inject, at what rate and what notch is the locomotive going out at when we do it,” adds Donikowski.

The NextFuel kit would provide a gas substitution rate of up to 80 percent, she says. GE recently shipped some demonstration kits to BNSF, which will test them for three to six months.

GE also is analyzing ways it can better use data obtained from the engine itself.

“There is all this information we can get from the systems and today, we only use the most basic form of it to keep the system running,” says Hall. “But if you look at that data in detail, you can start to optimize the system and get that last 1 percent of fuel efficiency, or use it in a diagnostic mode so you can tell what parts are going to go bad and when.”