Street lights are not normally planned to light up the driving route (Rationale being headlights are preferred for that), but to disclose signs and hazards outside of the headlights' usual view. Because of the dangers discussed above, roadway lights are properly used only sparingly and only when a exacting situation justifies increasing the risk. This usually involves an intersection with several turning movements and much signage — situations where the driver must take in much information quickly that is not inside the beam of his headlights. In situations like that (A freeway junction or exit ramp) the intersection may receive lighting so that the driver can speedily see all the hazards, and in a well-designed plan there will be gradually increasing lighting for a quarter-minute or so both before the intersection and gradually decreasing lighting after it. The main stretches of a highway remain unlighted to preserve the driver's night vision and increase the visibility of oncoming headlights. If there is a sharp curve where the headlights will not illumine the road ahead, a roadway light on the outside of the curve is often justified.

If it is desired to truly light a roadway, perhaps because it carries weighty volumes of fast multilane traffic, then to avoid the dangers caused by casual placement of street lights, it should not be lit intermittently, as this requires repeated eye readjustment which implies eyestrain and provisional blindness when entering and leaving light pools. In this case the system is instead designed to eliminate the need for headlights. This is usually achieved with bright lights placed on high poles at close standard intervals so that there is a consistent light level all along the route. The lighting goes from curb to curb.

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