Genset Locomotives: Implications for Type Testing in NSW

Abstract

All new locomotives need a “type” approval from the Environment Protection Authority to operate on the New South Wales rail network. To be approved, the locomotive type must meet noise criteria or:

• have noise emission performance consistent with current best practise

• have all reasonable and feasible measures for minimising non-compliance with the criteria and

• not result in unacceptable environmental impacts.

The noise criteria include overall A-weighted limits in all throttle settings, an overall Z-weighted limit for every throttle setting except for low idle, and limits on tonality for noise less than 1000 Hz. A multiple engine “genset” locomotive uses a system of at least two smaller engines to provide the same tractive effort provided by a large engine, and allows engines to be switched off when they are not needed. Two genset models can be used in NSW as they were approved by the EPA after testing against Environment Protection Licence noise criteria and best practise. In this paper I:

• briefly explain the testing and approval process for locomotives in NSW

• use a simple model to explore potential differences in exhaust noise tonality between gensets and conventional diesel-electric locomotives

• consider some implications of those differences.