Perhaps you were right all along, perhaps not

Environmental aspects of the 51m consultation response, part 17

I now plan to return to the previous series of blogs and continue my review of what Southdowns Environmental Consultants Ltd has said in Appendix 18 to the 51m alliance response to the public consultation (available here), which refers to criticisms that I have already made in earlier blogs.

In A little bit of magic (posted 17 May) and “We don’t believe you” (posted 25 May) I queried why no support had been provided in the AoS for the assumption made by HS2 Ltd that noise emissions from the next generation of high speed trains will be reduced by 3 dB overall due to “anticipated noise control improvements”.

The Southdowns report delivers the following verdict:

“… there is no guarantee that the claimed reduction in TSI emission noise limits will be delivered. Indeed, the Noise Action Plans indicate that the limits for start-up, pass-by and stationary noise are not expected to change. If the emission limits were to be delivered, however, then it is not unreasonable to expect that the reduced noise levels should be built into the base engineering case from the outset.”

So Southdowns appears to think that the delivery of the noise reduction is by no means certain.

In an attempt to get more clarity on this topic from HS2 Ltd, I asked for information on the basis for the assumed 3 dB reduction at a technical seminar led by the Chief Engineer of HS2 Ltd in early April. A written response reached me soon after I had posted “We don’t believe you”. This answer referred me to a document published in 2008, Technical Specification for Interoperability (TSI) relating to the rolling stock sub-system of the trans-European high speed rail system covered by EU Commission Decision 2008/232/CE (available here), and specifically paragraph (on page L 84/250), which says:

“It is recommended that in the case of new rolling stock to be ordered after 1 January 2010 Section and Section of this TSI is applied with a reduction of 2 dB(A) at a speed of 250km/h, and 3 dB(A) at speeds of 300km/h and 320km/h.”

Since paragraph is the one that specifies the maximum pass-by noise of a trainset, then this does seem to offer the 3 dB reduction that HS2 Ltd is claiming (although not specifically at 360 kph). I must say that I find this a strange provision to be in a technical specification; I have read a good number of such documents in my time and have never before seen one that offered a “post-dated cheque”, which is what the 3 dB appears to be.

However, as is so often the way in such documents, all is not totally clear because the same paragraph also says:

“This recommendation will serve only as a basis for revising section in the context of the TSI revision process mentioned in section 7.1.10.”

There is no 7.1.10, but 7.1.9 appears to be the paragraph in question as it says:

“In conformity with Article 6(3) of Directive 96/48/EC as modified by Directive 2004/50/EC, the Agency shall be responsible for preparing the review and updating of TSIs and making appropriate recommendations to the Committee referred to in Article 21 of this Directive in order to take account of developments in technology or social requirements. In addition, the progressive adoption and revision of other TSIs may also impact this TSI. Proposed changes to this TSI shall be subject to rigorous review and updated TSIs will be published on an indicative periodic basis of 3 years.

“The Agency shall be notified of any innovative solutions being considered by an applicant according to section 6.1.4 or 6.2.3, or by notified bodies when the applicant failed to do so in order to determine its future inclusion within the TSI.

“Then the Agency shall proceed according to section 6.1.4 or 6.2.3.”

I think that this means that HS2 Ltd can claim the 3 dB decrease in source noise (subject to my quibble about whether it extends to calculations at 360 kph), but that there is no guarantee if and when the limits in the Directive will be changed. What do you think it means?

However, the case for the 3 dB reduction becomes somewhat more uncertain if you consult an earlier version of the TSI for the rolling stock sub-system for high-speed railways, adopted in 2002 by EU Commission Decision 2002/735/EC (available here). This quotes (in paragraph 4.1.8 on page L245/419) exactly the same emission noise limits as the 2008 version of the TSI and permits (in paragraph 7.4.2 on page L245/445) the same 2 dB/3 dB reduction to be made for orders placed after a certain date. However this date is 1st January 2005, a whole five years earlier than is specified in the latest version.

So what might this be telling us? If the EU Commission expected train manufacturers to have achieved noise reductions by 2005 they must have been disappointed, otherwise they surely would have reduced the limits specified in paragraph of the 2008 version. That the Commission would have done this, had such reductions been achieved, is indicated by the following in paragraph 7.4.2 of the 2002 specification:

“This recommendation will serve as a basis for revising Section 4.1.8. in the context of the TSI revision process.”

So, if the prediction made in 2002 was wrong, what faith can we have that the 2008 prediction is any better?

I can’t help thinking that, instead of just gratefully grabbing the 3 dB offered by the TSI as a way of improving the impact figures, it would have been much better if the authors of the AoS had provided an explanation/justification of what they had done and had assessed the degree of technical risk involved.

Acknowledgement: I am grateful to Terry Brennan for alerting me to the contents of paragraphs 4.1.8 and 7.4.2 of 2002/735/EC.


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