All South West Train services from Dorking to London Waterloo have been cancelled until further notice due to signalling problems.
The issues have caused platforms 1 to 4 to be closed at the London terminus.
Customers are being advised to use Southern services, which will accept South West tickets.
On other routes from Surrey, Southern Rail reports most trains operating as normal.
Meanwhile on the roads, a broken down vehicle on the M25 clockwise at junction 8 (Reigate) has closed one lane, causing delays of up to ten minutes between junctions 7 and 8.
Slow traffic is also being reported on the A243 northbound at Leatherhead.
Further east, the M25 clockwise between junctions 4 and 6 is experiencing delays of up to 15 minutes caused by an earlier accident which closed a lane. Delays are expected until 8am.
