| Topic: | Re:Re:Re:Re:3rd runway noise in Chiswick | |
| Posted by: | Jeff Gear | |
| Date/Time: | 02/02/08 22:13:00 |
| Tom, My argument is along slightly different lines. Rather than forecasting noise in Grove Park in 2015, I was looking to determine meaningful numbers for the present noise levels experienced directly under the approach flight path. The spot I picked in Grove Park is analogous (same distance from runway threshold) to my own home's distance from a 3rd runway, and both directly beneath the approach. Best information available is the 2002 plots from the consultation. This shows 59dBA Leq for that spot. But the figure is a 16 hour average when the planes are only overhead for 8 hours, so during those "active" 8 hours the average noise level is surely 62dBA Leq. If a third runway is built that would approximate the average noise level in my bit of Chiswick while the planes are flying, which will be all day. If the landing intervals are doubled because of interleaved take-offs then 'my' average will drop back to 59dBA. The consultation map however indicates a figure of 54-55dBA for my area. That's why I think that even playing the average game the noise projections in the consultation are misleading. Err, wrong. I believe the basic problem at the heart of their numbers stems from using 16 hour averages where the planes are only overhead for 8 hours, which conveniently halves the average noise measure, or drops the number by 3dBA Leq. |