FINAL RULES on exhaust emissions issued by the US Environmental Protection Agency are estimated to add $252000 to the whole-life cost of a locomotive - though the impact will be gradual as the tighter standards are phased in between 2000 and 2005.

There are three levels, or tiers, of standards. Tier 0 applies to locos and engines built between 1973 and 2001, but only when remanufactured. Tier 1 covers production in the period 2002-04. All locos built from 2005 must conform to Tier 3 emission limits, or those in force at the time. A 2003 loco remanufactured in 2023 would only have to meet Tier 1, provided it was not fitted with an engine produced after 2004. Electric and steam locos are excluded altogether, along with diesel units built prior to 1973. The EPA says they ’do not contribute significantly to the emissions problem.’

Tier 1 engines are expected to continue in service until about 2040, by which time rail-generated nitrous oxide (NOx) emissions should have been cut by 60% compared to 1995, hydrocarbons by 50%, and particulates by 46%. Across the USA, this would amount to 650000 tonnes less NOx, and 12000 tonnes less particulates - barely 1% of the current national output from all transport modes.

Total average annual cost to operators is expected to be $80m, which the EPA points out is only 0·2% of 1995 freight revenues. The rules are seen by manufacturers and operators as a reasonable compromise, and similar standards may be adopted elsewhere. o