Diesel locomotive break down. Hydraulic transmission for locomotives was developed in Germany. There is still debate over the relative merits of hydraulic vs. electrical transmission systems: advantages claimed for hydraulic systems include lower weight, high reliability, and lower capital cost. By the 21st century, for diesel locomotive traction worldwide the majority of countries used diesel–electric designs, with diesel hydraulic designs not found in use outside Germany and Japan, and some neighbouring states, where it is used in designs for freight work. In Germany and Finland, diesel–hydraulic systems have achieved high reliability in operation. In the UK the diesel–hydraulic principle gained a poor
Diesel locomotive use of biodiesel). Diesel locomotive pollution has been of particular concern in the city of Chicago. The "Chicago Tribune" reported levels of diesel soot inside locomotives leaving Chicago at levels hundreds of times above what is normally found on streets outside. Residents of several neighborhoods are most likely exposed to diesel emissions at levels several times higher than the national average for urban areas. In 2008, the United States Environmental Protection Agency (EPA) mandated regulations requiring all new or refurbished diesel locomotives to meet Tier II pollution standards that slash the amount of allowable soot by 90% and require an