Disruption is being caused to railway services travelling to Chichester and Horsham following two incidents on the lines.
Southern Rail said lines travelling to Chichester were blocked after a train broke down earlier this morning (April 17).
The train has since been moved and lines have been re-opened but delays to services are expected to continue until 8.30am.
Disruption is also being reported on the Sutton to Horsham line.
Southern said lines between the two stations had been blocked following a signalling problem at Epsom.
Replacement buses have been requested and are expected to run between Horsham and Dorking calling at Ockley and Holmwood.
Engineers are working to fix the issue and services are expected to be delayed or cancelled until about 9am, the rail provider added.