Without more site specific detail we are unable to provide more information on the reasons fencing which obscures drivers' vision is being erected near traffic islands on the central reservation of dual carriageways.
Fencing may be erected on the Strategic Road Network for different reasons depending upon the needs of the location in question. The Highways Agency produce, maintain and apply standards and guidance for the different types of fencing used on the Strategic Road Network. These standards and site specific evaluations consider the risks and benefits before works commence.
Local Highway Authorities may choose to adopt these standards for use on the local road network.