You get a feeling for stuff on the road. A situation might make you uneasy for reasons unclear. The brain is a wondrous thing, able to recognise sets of circumstances that have proved hazardous in the past, sometimes before we are able to process them consciously. So don’t ignore these instincts – roll off for a moment and take stock.
Less spookily, your peripheral vision can be an excellent additional input. The human eye is better-tuned to small movements at the edge of its vision, like a wheel turning on a parked car, or a pedestrian emerging from behind a bus. Focusing hard on a main central vision point can enhance the peripheral sight – something jugglers know about, and useful when filtering.