Explanation

"This hatched area is bordered by broken lines; in normal driving, there shouldn't be a need to enter or cross the hatched area. When exceptional circumstances arise (for example, the need to pass a temporary obstruction or a slow-moving vehicle), you may drive on a hatched area when you're sure that it's safe to do so. Where hatched areas are bordered by a solid line, you mustn't enter the area except in an emergency."