A traffic light is supposed to reduce confusion and prevent crashes, but when it malfunctions, either showing conflicting signals, going dark, cycling erratically, or failing to detect cars, it can create a dangerous “everyone guesses” situation at an intersection.
In California, collisions caused by defective or improperly maintained traffic signals can involve multiple layers of liability, including negligent drivers and, in some cases, a public entity responsible for the signal’s operation and maintenance.
How Malfunctioning Traffic Signals Cause Serious Collisions
Traffic signal failures can lead to a variety of collisions, because it misinforms and confuses every approaching driver and depending on the congestion and design of the intersection, accidents such as high-speed collisions, T-bone crashes, pedestrian strikes, and chain-reaction collisions can happen at a moment’s notice.
Common malfunction scenarios include:
Conflicting green lights- Two directions get a green at the same time.
No signal / dark intersection- A power failure or internal fault leaves the light out entirely.
Stuck signal- The light stays red indefinitely (leading drivers to run it) or stays green too long.
Rapid cycling or inconsistent timing- Sudden changes cause rear-end collisions or risky “beat the light” behavior.
Broken pedestrian signals- “Walk” signals don’t activate or give insufficient crossing time.
Faulty detection systems- Inductive loops/cameras fail to detect vehicles, so the light doesn’t change.
Signal head misalignment- A light aimed incorrectly gives misleading information.
Even when a signal is malfunctioning, drivers still have legal duties at intersections. That’s where fault often becomes a shared (and heavily disputed) issue.
Who Has the Right-of-Way In These Situations?
When a signal is completely out (dark), drivers often argue about who “should have gone.” In practice, drivers who arrive first have the right-of-way and are urged to proceed with caution in the event a negligent driver is trying to maneuver their way around the intersection.
California’s Vehicle Code sets baseline rules for intersections and traffic control devices, including the requirement to obey official traffic control devices and rules governing signal lights and right-of-way. Relevant codes often implicated in these cases include:
CVC § 21450 (steady red signal duties)
CVC § 21451 (green and yellow signal rules)
CVC § 21452 (flashing red and flashing yellow rules)
CVC § 21453 (red light violations)
CVC § 21800 (right-of-way at intersections, including uncontrolled intersections)
Even if the light is acting up, a driver who speeds through, fails to yield, or doesn’t proceed with caution may still be found primarily (or partially) at fault. Additionally, it is important to note that police may cite one or more drivers for failing to yield or failing to use due care even if the signal failure started the chaos.
Injuries Commonly Seen in Signal-Related Crashes
Because many of these collisions happen in the middle of intersections, some of the most common injuries in these types of accidents tend to be severe. For instance, should you or a loved one have sustained any of the following injuries, it is urged to seek medical assistance immediately.
Traumatic brain injuries (TBI) and concussions
Neck/back injuries, herniated discs
Fractures (arms, ribs, hips, legs)
Internal injuries and organ damage
Lacerations, scarring, and soft tissue injuries
Wrongful death
Can You Sue the Government for a Car Accident Caused by a Broken Traffic Signal?
If a public entity (city, county, Caltrans, etc.) owned or controlled the intersection/signal and a dangerous condition contributed to the crash, then accident victims can file a claim against the government to recover compensation. However, the claim must demonstrate negligence and liability as outlined in the following California’s Government Code provisions:
Gov. Code § 835 (liability for dangerous condition of public property)
Gov. Code § 830 (definitions, including “dangerous condition”)
Gov. Code § 835.2 (constructive notice—when an entity “should have known”)
Gov. Code § 830.6 (design immunity, a common defense in roadway cases)
Public entities frequently defend these cases by arguing the condition wasn’t “dangerous,” or that the issue was a design decision protected by immunity.
Evidence That Can Make or Break a Malfunctioning Signal Case
These claims are evidence-heavy. Helpful proof can include:
Traffic camera / nearby business video (shows the signal behavior and the collision)
911/dispatch logs (calls about “light is out” or “stuck on red”)
Signal timing and phasing data (maintenance records, event logs, controller cabinet data)
Work orders and repair history (prior complaints and response times)
Police report/witness statements (especially witnesses who noticed the malfunction)
Photos/videos taken immediately after the crash (signal dark, flashing, conflicting, etc.)
Vehicle data (EDR/“black box,” dashcam)
Expert analysis (traffic engineering / human factors)
Tip: If you can do so safely, record a short video of the signal right after the crash (or have a passenger do it). Malfunctions can be intermittent, so early documentation is critical.
What to Do After a Suspected Malfunctioning Signal Crash
Call 911 and request medical assistance.
Tell the officer you believe the signal malfunctioned (conflicting lights, dark signal, stuck cycle, etc.).
Take photos/video of the signal and intersection (from a safe location).
Get witness contact info, especially anyone who saw the signal malfunction.
Seek medical care the same day if possible.
Avoid recorded statements to insurers until you understand the liability picture.
Talk to a lawyer early if a public entity may be involved due to the 6-month claim deadline.
Talk to a California Personal Injury Lawyer
Malfunctioning traffic signal cases can move fast especially when government claim deadlines, maintenance records, and video evidence are involved. If you or a loved one was harmed in a car accident in California, it’s important to speak with a lawyer from Frank Penney Injury Lawyers today to understand your legal options.
Our skilled car accident lawyers can investigate whether the intersection had prior complaints, obtain controller/event data, preserve footage, and identify every potentially responsible party. Contact us today at 888-888-0566 or by filling out our online contact form to schedule your free consultation.