From TFL website:

DARTMOUTH ROAD, SE23: Routes 122 176 and 197 are diverted northbound only and subject to moderate delays from 1000 Monday 27 October for about 3 weeks due to Victorian water mains replacement works.
DIVERSION
Towards Forest Hill:
From Kirkdale diverted ahead via Kirkdale, Sydenham Hill, Sydenham Rise, Routes 176 and 197 then divert left into London Road to line of route, Route 122 diverts right into London Road, Devonshire Road to line of route.