Drivers in Dorset have been warned to prepare for major delays as temporary traffic lights are introduced on one of Wimborne's busiest historic bridges.Dorset Council is launching a six-week trial on Julian's Bridge this week in a bid to improve safety for pedestrians and test whether a separate footbridge may eventually be needed.The Grade I listed bridge, which dates back to the 17th century, crosses the River Stour and is considered too narro…