If a traffic signal is malfunctioning, slow down well before the intersection and treat it as a stop-controlled crossing: a completely dark signal and a flashing red both require a full stop, a flashing yellow means proceed with caution, and a signal stuck on red calls for a different approach entirely. Getting the category right in the first few seconds is what keeps you out of a collision or a citation.
Dark Signals Work Like a Four-Way Stop
A dark signal has lost power and shows no lights at all. It is the most dangerous malfunction because every approaching driver loses their usual cue about who goes first. In most states, you are required to come to a complete stop and treat the intersection exactly like a four-way stop sign.1Federal Highway Administration. Signalized Intersections Informational Guide, Second Edition
- Stop fully before the stop line or crosswalk.
- Yield to whichever vehicle arrived first. If two arrive together, yield to the driver on your right.
- Don’t assume the other drivers know the rule. Creep forward, make eye contact, and go only when it’s clearly safe.
Dark signals are hardest to spot at night or in heavy rain, when the missing lights blend into the background. The earlier you recognize the problem, the more time you have to brake smoothly rather than slam to a stop.
Flashing Red and Flashing Yellow
Some signals default to a flashing mode when something goes wrong, and the color tells you what to do.
Flashing Red
A flashing red means stop. Under the Manual on Uniform Traffic Control Devices, you stop at the stop line, or before the crosswalk if there isn’t one, or at the point nearest the intersecting road where you can see oncoming traffic. Then you proceed when it’s safe, following the same rules as at a stop sign.2Federal Highway Administration. 2009 Edition Chapter 4D – Traffic Control Signal Features
Flashing Yellow
A flashing yellow means proceed with caution. You do not have to stop, but you must yield to pedestrians in the crosswalk and to vehicles already in the intersection. If you’re turning left or making a U-turn, also yield to oncoming traffic close enough to be a hazard.2Federal Highway Administration. 2009 Edition Chapter 4D – Traffic Control Signal Features
When the Two Directions Show Different Colors
Intersections in flashing mode often give the busier road a flashing yellow and the side street a flashing red. If you’re on the flashing-red approach, you stop and wait for a safe gap; the flashing-yellow traffic has the right of way. Misreading that split is one of the most common sources of collisions at malfunctioning signals.
A Light That’s Stuck on Red
A light that stays red through multiple cycles is a different problem. The signal is technically working, but it isn’t registering that you’re there. Many intersections use inductive loop sensors or cameras to detect waiting vehicles, and motorcycles, bicycles, and some small cars don’t always trigger them.
- Reposition over the sensor. The detection loops are cut into the pavement near the stop line and are often visible as circular or rectangular saw cuts. Rolling forward or shifting slightly can trigger the cycle.
- Try flashing your high beams. Some newer camera-based systems respond to headlight flashes, though older inductive loops will not.
- Turn right instead, where right on red is permitted, and reroute to your destination.
Running a red light that’s merely slow to cycle is illegal in most states, and there is no general federal rule letting you proceed after a set amount of time. About 21 states have passed “dead red” laws that let motorcyclists, and sometimes all drivers, proceed through a stuck red after specific conditions are met: typically a full stop, at least one complete signal cycle or a set wait (often 90 to 120 seconds), confirmation that no conflicting traffic is approaching, and then a cautious entry into the intersection. If you ride, check whether your state has a dead-red provision before relying on one.
Pedestrians and Cyclists
Cyclists in all 50 states have to follow the same traffic rules as motor vehicles. A cyclist at a dark intersection stops. A cyclist at a flashing red stops before proceeding. A cyclist at a flashing yellow yields to pedestrians and to vehicles already in the intersection.
Pedestrians facing a flashing yellow may cross in a marked or unmarked crosswalk but must yield to vehicles already lawfully in the intersection.2Federal Highway Administration. 2009 Edition Chapter 4D – Traffic Control Signal Features At a dark signal there’s no walk indicator at all, so treat it as an uncontrolled crossing: make eye contact with drivers, wait for vehicles to stop, and cross quickly. At a large or busy intersection, walking to a different crossing can be the safer choice.
If a Crash Happens
Fault at a malfunctioning signal can fall on the drivers, the municipality, or both. Drivers are expected to treat a broken signal as a stop sign and proceed with caution. If you drive through a dark intersection without stopping and hit someone, you carry the primary fault, and the malfunction doesn’t excuse you. The same goes for a flashing red: not stopping is legally the same as running a stop sign.
A city can share fault when it knew about the malfunction and failed to fix it in a reasonable time. Multiple ignored reports followed by an injury can support a negligence claim. Suing a public agency is harder than a standard insurance claim, though. Most states have sovereign immunity rules that require a formal notice of claim within a short window, sometimes as little as 30 to 180 days after the incident, and missing that deadline can bar the claim entirely.
If you’re in a collision at a broken signal, document the scene. Photograph the signal, note the time and lighting, and collect contact information from witnesses. File a police report and specifically mention the malfunction so it enters the official record.
Reporting the Malfunction
Reporting a broken signal protects every driver who reaches that intersection after you. Most cities accept reports through a few channels:
- 311, where available, is usually the fastest route by phone or text.
- A city website or app, often with an option to attach photos.
- The local police non-emergency line, if your area doesn’t run a 311 system.
Give the exact cross streets rather than a vague description, say what the signal is doing (dark, flashing red, stuck on one color), and note how long you’ve seen the problem. If the situation is actively dangerous with heavy traffic and near-misses, call 911 so officers can direct traffic until the signal is repaired.