by Prue Bray on 15 October, 2018
After all the vegetation on the M4 embankment was removed as part of the smart motorway project, I contacted Highways England for some more information. They have now replied. They haven’t said much about measuring noise levels without the trees there, but have answered pretty much everything else. The bad bit is that it looks like residents are going to have to have a year between removal of the existing noise barrier and its replacement with new better barrier.
In full they say
Dear Councillor Bray,
Thanks you for email of the 26 September regarding vegetation removal and noise from the M4. We have also received several emails from local residents in the area and we are working our way through responses to everyone who has contacted us.
Firstly, we accept that we should have provided better advance notice and explanation of these works and will ensure that this is done in future in all locations where vegetation clearance and other potentially disruptive works near to residential houses are taking place. The removal of trees and plants along the motorway is an unavoidable part of the project and we do understand local concerns about this. The difficulty we have with this is that we are restricted in when we can clear vegetation (i.e. outside the nesting season, which has just finished). Also, to deliver the project we effectively need to rebuild and/or re-profile the embankments which unfortunately cannot be done if significant amounts of vegetation is retained.
To answer your specific questions, baseline noise readings were taken south of Laburnum Road in 2014 showing average day time noise levels (over a 1hr period) at 64 dB in that location, although instantaneous levels could be higher. It was retested in 2017 and a 15 min average of 63 dB was shown – again, instantaneous levels may be higher. It is important to note that the noise attenuation in this location is provided by the Environmental Barrier at the top of the embankment and not from the vegetation.
A full suite of ecological surveys were undertaken across the scheme in 2016, 2017 and 2018 to inform the requirements of the Development Consent Order for the project. In this specific area, no instances of either protected or invasive species were found. However, prior to clearance the area was fully inspected by a licensed ecologist (we operate a permit system that requires the ecologist sign off before we proceed with any vegetation clearance) and permission was granted.
To answer the specific questions from residents.
1 We are scheduled to begin new landscaping in this area in April 2020, after the new environmental barrier has been installed. This will include replanting, where possible, as set out in the Discharge of Requirement 9 of the Development Consent Order.
2 The upgraded taller environmental (noise) barrier is scheduled to be installed at the end of the verge phase, to be completed by the end of March 2020.
3 The barrier needs to be removed and the new embankment built up and the roadworks at motorway level complete before the new environmental barrier is installed. The whole works phase in this section is due to start in May 2019 and be complete in March 2020. So unfortunately, there will be a period of time where there will not be a noise barrier at this location.
4 Further vegetation clearance will be happening everywhere up to the highway boundary between J10 and J11 and the works are all planned for this winter period. We will ensure that notifications go out in good time where they are close to residential properties.
5 The drainage in this location is being upgraded as part of the project and the maintenance responsibility during the smart motorway works transfers from the existing Roads Maintainer to the Smart Motorway Contractor.
6 The motorway effectively moves slightly to the north and the embankment is re-profiled – made steeper – as a consequence.
7 The new embankment is an engineered slope which needs to be cut into the existing embankment from the base level up in order to provide sufficient support for the upgraded motorway. Less vegetation has actually been removed so far than was indicated in the clearance drawings and we have asked our contractors to examine how they can achieve the works while removing less vegetation generally.
I hope these responses are helpful. We will improve our notification process and ensure that local residents are better informed about works in the future. If you would like a meeting so we can explain these points further, please do get in touch and we will arrange to visit you.
Thank you once again for your email, if I can be of any more assistance to you please do not hesitate to contact me.2 Comments