A three runway Heathrow; 700 more planes a day; can it really be quieter as is claimed

Here’s an odd thing.  The number of flights at Heathrow has more than doubled since the 1980s yet, according to official statistics, the number of people annoyed by the noise has fallen from 1.2million in 1980 to around 250,000.  http://www.heathrow.com/file_source/HeathrowNoise/Static/Noise_Action_Plan.pdf

But this is more than an historical curiosity. 

It matters for the future because the Department for Transport’s National Policy Statement, Heathrow Airport and Sir Howard Davies all argue that if a third runway – with 700 more flights a day – is built fewer people will be annoyed by noise from Heathrow than are today.

In my view, the apparent contradiction is down to the inadequate way noise annoyance has been measured. 

The noise of each aircraft is measured and the number of planes going overhead counted.  The noise is then averaged out over a 16 hour day but – and this is the critical point – too much weight has been given to the noise of individual aircraft and not enough weight to the number of planes passing overhead.  In 2003 HACAN published The Quiet Con which found that, using this measurement, one Concorde passing overhead once every two hours caused as much annoyance as a 757 flying over one every two minutes.  That is not how people hear noise.  http://hacan.org.uk/resources/reports/hacan.the_quiet_con.pdf

It is this which has allowed official figures to show that the numbers impacted by noise have fallen significantly while the number of planes using Heathrow has risen equally significantly.  And also why it can be claimed the number of people annoyed by the noise from a 3 runway Heathrow will be less than are currently affected.

I do, though, see signs of change in the air.  The Airports Commission, under Howard Davies, did a good job in updating the noise metrics.  And the Government’s recent consultation on airspace policy built upon that.

There are two critical changes that are proposed.

One is the recommendation that, in assessing noise annoyance, in addition to averaging out the noise, decision-makers should take account of the number of aircraft going over head and the loudness of each individual plane.

Secondly, the cut-off point of where people start to get annoyed has been lowered.  It used to be where the noise averaged out at 57 decibels over a 16 hour day.  That was unrealistically low.  It excluded places like Putney and Fulham where aircraft noise is clearly a problem.

The new cut-off point, expected to be announced by the Department for Transport (DfT) shortly, is likely to be 54 or 51 decibels.  It is backed up by research the DfT commissioned from the CAA.  This shows that 9% of people are highly annoyed when the noise averages out at 54 decibels and 7% at 51 decibels.  http://publicapps.caa.co.uk/docs/33/CAP%201506%20FEB17.pdf.  In geographical terms around that goes as far as about Clapham to the east and about 16 miles to the west: around 65,000 people in total.  The lower average of 51% extends about as far as Peckham.

The expected new metrics are not perfect.  For example, they do not adequately measure the real level of annoyance of people in areas that may just have planes for part of the year but, when they do so, are badly hit.  Places such as Teddington and Ealing are overflown for about 30% of the time in a typical year (when an east wind blows).  They fall outside the annual noise annoyance contours. There needs to be a metric to capture their situation.  But, on the whole, the new metrics have the potential to reflect more accurately the situation on the ground.

So is it at all possible that a three runway Heathrow – with 700 more flights a day – will be quieter than the two runway airport is today?  Individual planes will become less noisy, operational practices will improve and noise annoyance will be measured more accurately.

But, over the last quarter of a century, the problem for residents has been the sheer volume of planes going overhead.  700 more with a third runway.  Of course that number includes landings and take-offs and it is not 700 over any one community.  And measures to increase the angle of descent and ascent will assist.  And creative thinking about respite will be important; indeed will be essential.

But it is that 700 figure which worries communities.  It is like 700 dark clouds on the horizon.  It is the basis of community opposition to a third runway.

Comments are closed.