I read an article recently about conspicuity for police officers working on the highway. It suggested that the reflective vests and jackets that we use to stand out and be identified by drivers at night were not very effective. A driver had to approach closely when using low beam headlights to see a reflection, and the reflections that were seen did not immediately suggest that what the driver was looking at was a pedestrian.
The problem with low beam headlights is that they initially illuminate the area of a pedestrians feet and by the time they reach the mid and upper body, it is too late for the driver to react to what they are seeing.
Tests in a driving simulator produced an even more surprising result. 60% of drivers who were warned that a pedestrian would appear during the simulation failed to see them on the roadway in time to avoid colliding with them. Often drivers report that the first indication that they had of a pedestrian being present on the highway is when they heard the sound of the collision with them.