This is Marlborough Hill, Kingsdown, the secret road through the BRI. The sign says "New Road Layout Ahead"
The changed layout was a narrowing of the road, so as to discourage cars from driving the wrong way down a one way street without noticing. It is based on two assumptions: the driver notices, and that the driver cares. For those drivers who do need to use this high-performance route from Kingsdown to Marlborough Street -and hence the M32- the main problem with this new road layout is that the road is now too narrow for you to squeeze past bicycles. Fortunately, it's a very steep hill and bicycles will be grateful for any excuse to rest.