Which of the following is an example of a 'systemic' approach to safety, as opposed to a 'hot spot' approach?

1. Installing a traffic signal at the intersection with the highest crash count in the city
2. Adding left-turn lanes at all intersections on arterials that share risk characteristics associated with left-turn crashes
3. Conducting a detailed crash analysis at a single high-crash location
4. Implementing a speed reduction zone at a specific school