Lines have fully reopened and services are returning to normal.
Rail passengers are facing delays of up to 40 minutes heading into London Paddington due to signalling problems between Maidenhead and Slough.
The signalling fault means trains have to run at a reduced speed on all lines heading towards Paddington.
Operator Great Western Railway is warning trains may be cancelled, delayed or revised.
Disruption is expected until noon.
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The crash, which took place at about 7am today (Thursday), involved three vehicles. One man sadly died as a result of the collision and his next of kin have been informed.