Idaho · Handbook chapter 3 · 5 min read
Chapter 3: Signs, signals and pavement markings
Idaho's regulatory, warning, work zone and guide signs, barricades, traffic lights, flashing arrows, pedestrian hybrid beacons, and the yellow and white lines painted on the road.
Why this chapter matters
The Idaho knowledge test covers highway signs by shape and symbol, traffic signals and pavement markings. Learn the sign colors, what each light means, and which lines you may cross.
Who controls traffic
Signals, signs and pavement markings are traffic control devices, and you must also obey police officers, highway workers and school crossing guards. Uniformed school safety patrols, wearing a badge or "School Patrol" insignia and holding STOP or other signs, must be obeyed too.
Sign colors and shapes
| Type | Look |
|---|---|
| Regulatory | Mostly black and white, some red and white |
| Warning | Mostly black on yellow diamonds; school signs may be fluorescent yellow-green |
| Work zone | Orange and black |
| Guide | Green for directions and distance, blue for services, brown for recreation and history |
Regulatory signs
- STOP: stop at the marked stop line. With no line, stop before the crosswalk on the near side. With neither, stop where you can see traffic on the cross road before you enter it.
- YIELD: slow down and give the right-of-way to vehicles and pedestrians; stop if needed. If people are in or about to enter the crosswalk, stop until they have crossed.
- DO NOT ENTER: you may not enter from your direction.
- SPEED LIMIT: the maximum under ideal conditions.
- KEEP RIGHT: the road is divided ahead; stay right of the island or barrier.
Work zones
- Expect uneven pavement, narrow lanes, gravel and equipment; workers may be inches from traffic, night and day.
- Fines for speeding increase in work zones where signs say so. Do not follow closely, and keep distractions down.
- ROAD CLOSED means only authorized vehicles may enter. ROAD CLOSED TO THRU TRAFFIC or LOCAL TRAFFIC ONLY means you may enter only if you need to stop inside the zone.
- Never drive around or move barriers to cross a closed road.
- The slow-moving vehicle emblem marks farm or construction equipment; slow down and approach with care.
Common warning signs
- Open range: livestock may roam freely and have the right-of-way.
- 3-way (T) intersection: you must turn left or right, and you must stop and yield to drivers from the other two directions.
- Crossroad, signal ahead, merging traffic, added lane and lane ends (merging traffic must yield).
- Two-way traffic: a divided highway changes to a two-lane, two-way road. Divided highway ends: watch for oncoming cars.
- School zone and school crossing: watch for children, slow down and obey crossing guards. Penalties are higher for school zone speeding.
- Pedestrian crossing: people on foot have the right-of-way.
- Hill: a steep downgrade; check your brakes. Slippery when wet: slow down in wet weather. Low clearance: little room overhead.
- No passing zone: a yellow pennant on the left side of the road.
- Share the road: placed under a bicycle sign where there are no bike lanes.
- The railroad Emergency Notification System sign gives a phone number and crossing number to report a problem or stalled vehicle.
Barricades
Red and white barricades are permanent; orange and white are temporary. The meaning is the same. A V pattern means the road is closed. Stripes sloping down to the left mean pass on the left; sloping down to the right mean pass on the right.
Traffic signals
| Signal | Meaning |
|---|---|
| Steady red | Stop before the stop line, crosswalk or intersection. You may turn right after stopping unless a sign forbids it |
| Flashing red | Same as a STOP sign |
| Steady red arrow | No turn in that direction until a green or yellow allows it |
| Steady yellow | The light is about to turn red; stop if you safely can, or clear the intersection if you are already in it |
| Flashing yellow | Slow down and go with caution |
| Steady yellow arrow | The turn signal is ending |
| Flashing yellow arrow | Turn after yielding to oncoming traffic and pedestrians |
| Green | Go, but yield to oncoming traffic and pedestrians when turning left, and do not enter unless there is room to clear the intersection |
A "doghouse" signal is usually for protected left turns. If a signal is dark or not working, treat the intersection as a four-way stop.
Pedestrian hybrid beacons (HAWK)
Two red lights over one yellow. The beacon is dark until a pedestrian pushes the button, then shows flashing yellow (slow down), steady yellow (prepare to stop) and two steady reds (stop at the line). When the reds flash alternately, stop, yield to anyone in the crosswalk, and go when it is clear.
Pavement markings
- Dashed yellow center line: either direction may cross to pass when safe.
- Double solid yellow: no passing. You may cross only to turn left into or out of a driveway or business.
- Solid and dashed yellow: only drivers on the dashed side may pass.
- Shared center turn lane: solid and dashed yellow on each side; for left turns (and U-turns where allowed) only, never for travel.
- Solid white edge line: marks the road edge, helpful at night.
- Dashed white lines: separate lanes going the same way; never straddle them.
- Solid white lane line: avoid changing lanes. Double solid white: lane changes prohibited.
- Solid white line with a bicycle symbol: a bike lane, ridden in the direction of traffic. Dashed bike lane lines let drivers turning right merge into the bike lane, yielding to any bicyclist already there. Green paint marks where bikes and cars cross paths.
Frequently asked questions
What color are Idaho work zone warning signs?
Orange with black lettering or symbols.
What should I do when a traffic light is out?
Treat the intersection as a four-way stop.
Can I turn right on a red light in Idaho?
Yes, after a full stop and yielding to cross traffic, unless a sign prohibits it.
May I cross a double yellow line?
Only to turn left into or out of a driveway or business entrance. You may not pass.
What does a flashing yellow arrow mean?
You may turn after yielding to oncoming traffic and to pedestrians in the crosswalk.
Based on the Idaho Driver's Handbook (July 2026), Highway and Vehicle Knowledge: Signs, Signals and Pavement Markings.