Overrun area

An overrun area is a portion of road surface that is designed to accommodate the turning circles of large vehicles, while ensuring tight geometry (to slow down speeds) for conventional vehicles. Although it is possible to drive over these areas, their appearance and design discourages people doing so. 

Overrun areas are typically found in the centre of roundabouts with tight 'continental geometry'; they allow buses and lorries to negotiate these roundabouts, while at the same time ensuring drivers of smaller vehicles have to slow down.