If an obstacle is present, how far back should warning triangles be placed?

Answer: B — 500 feet

Warning triangles are a critical safety feature for commercial vehicles, especially when a driver is forced to stop on the side of the road due to an obstacle or breakdown. The proper placement of warning triangles helps alert oncoming traffic to the presence of a vehicle that may pose a hazard, allowing them to react appropriately. The correct distance for placing warning triangles, particularly in the case of an obstacle, is 500 feet back from the obstruction. This distance provides sufficient warning to drivers approaching the area, giving them the time they need to slow down and avoid potential collisions. Additionally, this distance is in line with guidelines provided by the Federal Motor Carrier Safety Administration (FMCSA), which emphasizes the importance of being visible from a significant distance in order to enhance safety for both the stopped vehicle and oncoming traffic. While other distances like 200 feet, 800 feet, or 1000 feet might seem like reasonable alternatives, they either do not provide enough warning time or are excessive, potentially leading to confusion or unnecessary barriers on the roadway. Hence, correctly positioning the triangles at 500 feet strikes the right balance between visibility and practicality.