What do these zigzag lines at pedestrian crossings mean?

Explanation: The approach to, and exit from, a pedestrian crossing is marked with zigzag lines. You must not park on them or overtake the leading vehicle when approaching the crossing. Parking here would block the view for pedestrians and the approaching traffic.

Category: Road and Traffic Signs

References: The Official DVSA Guide to Driving: Section 6, Highway Code: Rule 191, Know Your Traffic Signs: Page 122