Work has started on a 45 million pound project to double a twelve mile length of track between Swindon and Kemble stations.
There has been just a single railtrack between the two stations since the late 1960s, when one of the tracks was removed to save money.
Network rail says the work should be finished by march and will mean up to four trains per hour will be able to run in each direction.
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Bitterly cold dry and bright.
Dry and bright but bitterly cold.
Clear skies over North Devon, Somerset and Dorset will bring a sharp frost. Tomorrow will start cold but the sun will improve things