The A505 has been shut northbound between Baldock and Royston due to a fallen tree.
Herts Highways confirmed that the Royston Road stretch of dual carriage had been shut an hour ago, and it remains closed at this time.
Motorists are being diverted through Baldock.
The county has been hit by strong winds today as part of Storm Barney, with the Met Office issuing a weather warning for the eastern region.
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