Welsh Liberal Democrat leader Kirsty Williams says scrapping the tolls on the Severn Bridges would cost the UK Government around £15m a year once the construction bill is paid in 2018 and debts associated with the bridges are settled.
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There will be a fresher feel with temperatures falling lower than on recent nights.
The accident between junction 24, Coldra, and 23A, Magor, has closed the eastbound carriageway.
Eloise Parry, 21, died after taking diet pills containing the poisonous Dinitrophenol (DNP).