A4232 through the bay

With anyone else, I'd explain. With you, it would be pointless!

The speed limit reductions has been used successfully on the M4 in Newport, but this is a different problem (that of easing stopping and starting, and aiding a steady stream of traffic) not related to noise pollution.

What is the relationship between traffic density, speed and actual noise level anyway? It won't be a linear relationship since perception of noise is logarithmic (hence the dB scale). I wonder if reducing the speed limit would even have a significant perceivable effect anyway. It's not as if the volume of traffic on the A4233 is currently excessive.

Drag (what causes sound waves) is proportional to the square of velocity and as you say sound is perceived in a log base 10 scale so halving of velocity would reduce noise by just 40% or so (log4)

I must admit it's my least favourite part of doing the bay circular walk, as the sound of vehicles is deafening and relentless. As with, let's face it, the whole of Cardiff it's the quality of the road surface that causes a lot of road noise, coupled with the fact that most modern cars have larger and wider wheels it all adds up to a loud constant roar.

By comparison the new widened M4 from junction 29 - 32 is whisper quiet, you don't have to walk too far into Cefn Onn before it recedes into the background. But I know they paid a lot of attention to the drainage and noise reduction on that stretch.

It's not as if the volume of traffic on the A4233 is currently excessive.

Simon, you don't commute in and out of Cardiff

Just to add that i find the noise deafening on the bay bridge, stops us wanting to walk all the way around the bay. We usually divert up to the next bridge. With the thought of the eastern link being built, the noise will increase significantly along these stretches for home owners. I cant see a problem in restricting the speed through this short section next to the bay and by the tunnels, especially as there are quite a few junctions in a short stretch of space.?

I am not a fuddy duddy but yep I agree with reducing the speed in certain stretches.
The tunnels for one are a 50mph limit but nobody does 50 in it.
In fact motor bikes and hot hatches use it to sound off their exhausts as they go through and speed up!
Average speed cameras at each bore.

On the circular walk, yes the next bridge is so much quieter and relaxing.

Have you ever walked across the original Severn bridge? strange sensation walking along beside a motorway.

The one time i walked it, it was closed to traffic so was very serene! Walking the bay bridge in San Francisco and Sydney harbor bridge was very different though, similar to Cardiff bay bridge

The A4232 is an essential road for Penarth, The Bay and Cardiff generally but playing Devils advocate for a moment why is it essential that the elevated section over the Taff and Ely has to have a 70 mph limit on a good bit of road which is not congested and flows well ?

The A4232 is an essential road for Penarth, The Bay and Cardiff generally but playing Devils advocate for a moment why is it essential that the elevated section over the Taff and Ely has to have a 70 mph limit on a good bit of road which is not congested and flows well ?

I agree, let's raise it to 100mph