Influence of Duty Cycles and Fleet Profile on Emissions From Locomotives in Canada

Analyses were carried out of the exhaust emissions from locomotives in Canadian railway operations based on data as of the end of 2001. The authors found that locomotive technology used in the fleet significantly influenced the emission factor while duty cycles had a lesser influence. This is because despite using less fuel for the horse-power produced, the newer diesel engines produce more emissions per unit of fuel consumed. Since 1997, there has been a significant change in the locomotive fleet profile as the Canadian Class I railways replace their 1970s’ era 3,000HP SD-40 type locomotives with modern fuel-efficient 4,300 to 6,000HP locomotives. The new locomotives being introduced, or when re-manufactured, after January 1^st 2000 meet the Tier 0 emission standards of the U.S. Environmental Protection Agency. Unlike the U.S.A. where the emissions limits are the subject of legislated standards, the current Canadian situation is a voluntary one aiming to keep, country-wide, locomotive emissions of oxides of nitrogen (NOx) below a cap of 115,000 tonnes per year. The authors’ analyses provide a database upon which trends and scenarios can be examined vis-a-vis the voluntary cap set by the Railway Association of Canada for the period 1995 to 2005 in its Memorandum of Understanding with Environment Canada regarding railway locomotive emissions.