That’s totally out of order

Environmental aspects of the 51m consultation response, part 12

In my blog It’s on the level (posted 8 Jul) I made some comments about the colour gradings (red, yellow and grey) that HS2 Ltd has used in the AoS to classify dwellings at risk from noise annoyance from HS2; in particular, these comments were addressed at the noise level thresholds that have been specified. In Appendix 18 to the 51m alliance response to the public consultation (available here) Southdowns Environmental Consultants Ltd has made some enlightening observations on this topic, and so I thought that I would take this and the next couple of blogs to revisit this subject in the light of this additional information.

In order to conform to the practice used in the AoS any levels that I specify in the blogs on this topic will be the equivalent continuous noise level over an eighteen-hour period (dBA L_{eq, 18hr} or L_{Aeq, 18hr}); for convenience, I will use just dBA to represent this value (unless quoting from another document that uses a fuller form).

In this blog, I will look at the highest level set by HS2 Ltd, which is termed in the AoS as “high noise level exposure” and indicated by a red dot on the noise maps in section 3.5 of Volume 2 of the AoS. The criterion set for this rating is specified in paragraph 6.1.1 on page 48 of Appendix 5 to the AoS (available here) as “a free field noise level greater than or equal to 73 dB L_Aeq,18hr”. This level is justified by a footnote on the same page, which says “This criterion for railway noise exposure has been used in the past by Defra, to identify First Priority Locations for Noise Action Planning as part of The Environmental Noise (England) Regulations 2006”.

My comments on this criterion in It’s on the level were that it was “pretty loud” and “at least as loud as living at the end of a Heathrow runway”. In fact it is so loud that Southdowns is crying “foul”, citing the Defra Noise Action Plan for Major Railways (available here), and specifically paragraph 5.07 on page 17 which states with regard to the 73 dBA threshold level that it “should only be used for the purposes of identifying First Priority Locations for investigation in the context of this Noise Action Plan and should not be used for any other purpose or in any other policy context”.

(The same statement also appears in the Noise Action Plan for the London Agglomeration, which is also cited by Southdowns).

Using this threshold for an “other purpose” and in another “policy context” is precisely what HS2 Ltd has done. The Southdowns report calls the project definition of a threshold using this level “unprecedented” and describes its inclusion in the AoS assessment “questionable and open to challenge”. It also says

“In summary, application of the NAP First Priority Location criterion level to the HS2 project breaches Defra’s explicit preclusion on its use outside the context of Noise Action Plans for the initial prioritisation of the management of noise from existing sources. It is considered that this level represents an extreme and very high noise level for the assessment of noise impacts from new development outside existing dwellings.”

The report also says that

“The Noise Action Plans indicate that in due course relevant rail authorities will be asked to examine other Important Areas which do not contain First Priority Locations and where noise levels thus fall below 73 dB L_Aeq,18hr . The stated anticipated year of HS2 opening is 2026 and it is considered therefore that the focus of Noise Action Plans should have moved on by then and that the focus will be on addressing the management of environmental noise at levels below HS2’s threshold value for High Noise Levels, given that the Noise Action Plans are scheduled for review at least once every five years.”

The Southdowns report suggests an alternative criterion for “high noise level exposure”:

“Most European railway noise limits do not exceed a daytime level of 65 dB L_Aeq,T and it is concluded that a more appropriate project definition of ‘high’ daytime noise level would be 65 dB L_Aeq,T and that the HS2 ‘High Noise Level’ criterion detracts from the substantive impacts that properties will experience at levels below a daytime noise level of 73 dB L_Aeq,18hr.”

As I said in the title to this blog, HS2 Ltd is “totally out of order”.