This chapter explains what Illinois' traffic signals, lane signals, and pavement markings mean and when you may legally proceed. It covers steady red/yellow/green lights, flashing red and yellow lights, turn arrows, pedestrian "Walk"/"Don't Walk" signals, and overhead lane-control signals used on expressways.
Pavement-marking questions are heavily tested: solid vs. broken white lane lines, single vs. double yellow center lines, no-passing zones, two-way left-turn lanes, and railroad-crossing markings. Know which lines you may cross to pass or turn and which you may never cross.
A frequent mistake is treating a flashing yellow light as a full stop — it only calls for caution, not a stop. Another is forgetting that at a signal that has stopped working entirely, every direction must treat the intersection as an all-way stop.
What's the difference between a flashing red light and a flashing yellow light?⌄
A flashing red light means you must stop completely, yield to traffic in the intersection, and then go when it is safe — treat it like a stop sign. A flashing yellow light only warns you to proceed with caution; it does not require a full stop.
When am I allowed to cross a double yellow center line?⌄
Double solid yellow lines mark opposite-direction traffic and normally may not be crossed, but you may cross them to make a left turn into or out of an alley, private road, driveway, or street.
What should I do at an intersection where the traffic signal is not working?⌄
Treat the intersection as an all-way stop: come to a complete stop, then look and yield the right-of-way before entering, unless a law-enforcement officer is directing traffic differently.