A38 in both directions is blocked, and there are long delays due to an accident near B3271 Liskeard Road. One of the vehicles involved has gone off the road.
Police say the road could be blocked for some time.
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Some people in North Prospect say they do not want to leave as the local housing association continues its regeneration.
A chilly start with bright spells and scattered showers. These will gradually ease off through the afternoon.
It will be cold and windy, with sunny spells and wintry showers gradually turning back to rain and slowly easing through the afternoon.