Similar to stop and yield signs, traffic lights are designed to control the flow of traffic on the roadways. But because traffic signals rotate colors, the rules are more complicated than those that apply to stationary traffic signs. This article outlines the details of traffic light laws, some common exceptions to red light rules, and some possible penalties for red light violations.
In every state, traffic signals rotate between green, yellow, and red to control crossing flows of traffic. However, the details of state laws differ in terms of what they permit drivers to do when approaching different colors of signals.
Green signals. A green signal universally permits drivers facing the light to proceed through the intersection without stopping.
Yellow signals. A yellow signal is a warning that the light will soon turn to red. But state laws differ with regard to what drivers must do when approaching a yellow light. In some states, drivers can still enter and pass through an intersection when facing a yellow signal. So long as the vehicle's front wheels pass the limit line on the nearest side of the intersection prior to the light turning red, the driver can continue through the intersection without violating the law. However, some states prohibit drivers from entering the intersection after the light has switched to yellow. In these states, the vehicle's front wheels must pass the near limit line prior to the light turning yellow. Otherwise, the driver can get a ticket for running the light.
Red signals. Drivers approaching a red signal are required to stop. Drivers generally must stop prior to the nearest of the limit line, the pedestrian crosswalk, or the intersection itself. So, a driver can get a red-light ticket for rolling through a red light or just pulling too far forward prior to stopping.
Generally, states laws contain a few exceptions to the normal traffic signal rules. For instance, emergency vehicles are typically permitted to proceed through red lights (with caution). Also, state laws normally have exceptions for situations where a driver goes through a red light at the direction of a police officer or as part of a funeral procession.
But the exceptions that come into play most often relate to turning on a red light and motorcycles at signals that are triggered to switch by weight or infrared sensors.
Turn-on-red exceptions. After coming to a complete stop at a red light, drivers are generally permitted to make a right turn unless otherwise there's a sign specifically prohibiting it. In the past, many states prohibited drivers from making a right turn at a red light. However, all states now permit drivers to make a right turn at a red light (with the exception of New York City and cities in New York with populations of a million or more).
Many states also allow drivers to make a left turn on red if the driver is on a one-way street intersecting another one-way street proceeding left. And a few states permit drivers to make a left on red from a two-way street onto a one-way street.
With both red light turning exceptions (right and left turns), the driver must yield to intersecting traffic.
Motorcycle exceptions. Many states also have exceptions to the normal red light rules for small vehicles like bicycles and motorcycles. Many traffic signals are triggered to switch by weight or infrared sensors. These sensors work well for full-size vehicles but aren't so great at detecting smaller vehicles. If the motorcycle or bicycle is too small to register on the sensor, the light may never change. To address this issue, many states allow motorcyclists and bicyclists to proceed through a red light after waiting a reasonable amount of time if it is apparent that the signal is not going to change.
Traffic infraction tickets. In most states and cities, running a red light (or yellow light in states that don't allow it) is a traffic infraction. Depending on the jurisdiction, a red light ticket might carry a fine in the range of $100 to $500. A red light ticket is typically considered a moving violation, so the DMV will normally record the violation and might assess demerit points to the driver's record. In most states, getting too many traffic violations or demerit points within a certain period of time can result in license suspension.
Misdemeanor tickets. A few states charge traffic signal violations as misdemeanors, which generally carry up to one year in jail in addition to fines. However, it's rare for a driver to get jail time for a red light ticket.
Traffic school. Many states have some form of traffic school. Eligible drivers might be able to avoid some or all of the penalties for a red light violation by completing traffic school.