It's a pretty sophisticated resource, with maps produced by postcode, time of day, major roads excluded or included etc.
What's interesting about the article that accompanied the piece in TimeOut is that it showed that Londoners find road noise to be their great source of irritation. In a world obsessed by anti-social behaviour laws and apparently over-run by block-parties and noisy-neighbours, it's actually traffic that is the most anti-social beast in town. I doubt I'd get very far trying to put in an ASBO on cars and scooters, but research like the London Noise project - funded by DEFRA - does give designers and architects the tools to try to reduce the impact road noise has on our lives.
On another point, I think it's also fascinating that even though we have become such visual beasts - spending so much of our time staring at screens - anti-social behaviour is still essentially a majority aural problem. It's very easy to close your eyes. It's bloody hard to close your ears. One feels that there perhaps needs to be a rebalancing of effort here. So much time and money is spent improving the 'look' of our cities - the visual environment - but given this fact that it's the aural that affects our perception of calm and peace, perhaps more ought to be spent on the 'sound' of our cities too.