GWML - trains using relief lines only into Paddington this morning

[Jamiescott1]

This morning it seems that trains heading into Paddington on the gwml are switching from mains onto the relief lines at Slough until Southall for the journey into Paddington.
Trains are still running west bound on the mains.

Anyone know why?

 

[59CosG95]

This morning it seems that trains heading into Paddington on the gwml are switching from mains onto the relief lines at Slough until Southall for the journey into Paddington.
Trains are still running west bound on the mains.

Anyone know why?

Just checked the maps on OpenTrainTimes - trains are using the Up Main again.
Must have been engineering work.

 

[Mag_seven]

Just gone over a 20mph emergency speed restriction on the up main in the Airport Junction area. Suspect the line was closed earlier whilst it was put in place.

 

[Bedwyn32]

Think this is why. It is from the Network Rail section of SWR Tyrell information