Final answer:
The mandatory left turn sign indicates traffic in the left lane must turn left and is marked by an arrow pointing left. This sign is vital for traffic safety and pedestrian safety at intersections.
Step-by-step explanation:
The sign that indicates traffic in the left lane must turn left at the intersection ahead is commonly known as a mandatory left turn sign.
This sign is often characterized by an arrow pointing left, clearly indicating that vehicles in the respective lane have to follow the direction of the arrow and make a left turn.
It is crucial for traffic safety that drivers obey such signage to prevent accidents and ensure an orderly flow of traffic, especially in high-risk areas such as intersections near campuses where pedestrian safety is a major concern.
Recognizing and following traffic signs are essential skills for drivers and an important part of road safety education.