Understanding Traffic Laws

Imagine what the roads would be like without any traffic laws. It would be chaos! Traffic laws help to regulate the progression of cars on roads and highways, thus minimizing accidents.


Traffic laws vary from State to State, but most have some sort of commonality. This uniformity is largely due to historical practices, institutional collaborations and modern Federal oversight.

Speed Limits

A speed limit sets the maximum allowed vehicle speed on a roadway segment. Speed limits are posted on a sign and are usually expressed as miles per hour or kilometers per hour. Traffic engineers conduct engineering speed studies to determine an appropriate maximum speed for a road segment. These studies are based on prevailing speeds, engineering design criteria, and other factors.

Arbitrary, unrealistic speed limits lead to a general disregard of the law and put motorists at risk. In fact, studies show that lowering speed limits below the 85th percentile speed increases accidents at those sites.

Most States have statutory speed limits set by the State legislature. These statutory limits are then adjusted by the local governments, including cities and towns. These adjustments may be done with or without an engineering speed study, depending on the city’s or town’s policy.

When the statutory speed limit is exceeded, the driver can be cited for speeding. However, the speeding ticket can be acquitted if it can be shown that the driver was driving safely for the conditions and traffic flow at the time of the violation.

Some States allow cities and towns to rescind special speed regulations, such as 50 mph on residential roads, by sending in a written request to the State Transportation Agency with the roadway names, starting and ending limits and coordinates to mark the start and end of the special speed zone. However, a city must perform a study to determine the proper statutory speed limits before this can happen.

Stop Signs

The red and white regulatory sign known as a stop sign can be found just about everywhere there are cars and people. Its octagonal shape makes it easy to recognize by both its color and shape, and it warns drivers that they must come to a full stop before proceeding through an intersection. When you see a stop sign, you must bring your vehicle to a complete halt at the stop line or 4 feet in advance of the crosswalk and make sure that the road is clear before driving forward again.

Unlike traffic lights, which give directions based on the color and pattern of their light, stop signs require that you read the message. The word STOP is spelled out in bold letters, and there are no arrows that indicate what direction to proceed. The word is also written in the center of a yellow background. The yellow background is meant to increase the visibility of the sign when it is raining, snowing or foggy.

Stop signs are usually placed at intersections where an engineering evaluation indicates that a right-of-way assignment is needed to reduce traffic conflicts and crash potential. However, they can be used in other locations where prevailing traffic conditions and reported accident data warrant the use of such a sign. Typically, YIELD or ALL-WAY stops are not warranted for this purpose because they tend to result in higher right-angle accidents — the very type of accidents that they are designed to prevent.

Right of Way

Few areas of traffic law are more misunderstood than the “right of way.” It does not give you a special legal status or immunity, but it does specify when you must yield (let another driver go before you in an intersection). Failure to yield was one of the top four causes of deadly car accidents nationwide in 2018.

Controlled intersections with stop signs and/or traffic lights are the easiest situations to determine right-of-way. If you arrive at an intersection at the same time as a vehicle that is already in the intersection making a turn, it’s your duty to yield and let them finish their turn before you proceed straight through the intersection.

Uncontrolled intersections are trickier because there are no stop signs or traffic lights to guide you. As a general rule, drivers who come to the intersection first get to go first. But you must also yield to cars arriving at the intersection from perpendicular directions.

Some vehicles have the right of way automatically, such as emergency vehicles displaying their flashing lights and sounding their sirens or air horns. You must yield to these vehicles even if the light is green, and even to a stopped or stalled vehicle. You must also yield to pedestrians or cyclists crossing the road in a crosswalk, and to blind pedestrians who are using a white cane or other signaling device.


Whenever a car comes to an intersection or a junction where a different vehicle is already present, the driver of the first vehicle must yield the right of way. This is one of the most confusing aspects of traffic law and why it is important to be alert and watch out for drivers flouting rules of yielding.

A failure to yield the right of way can cause T-bone collisions, sideswipe accidents and head-on crashes. It can also cause injuries to pedestrians, bicyclists and motorcyclists.

Yielding can take place at traffic lights, four-way stops and even in a roundabout. For example, a vehicle entering a roundabout from the outer lane must yield to cars already in the circle.

Another time when a driver must yield is when turning from a side road onto the main road. In many cases, this requires drivers to reduce speed and make eye contact with oncoming vehicles. Drivers should also yield when merging on to highways or leaving parking lots.

A recent accident in Florida highlights the dangers of failing to yield the right of way. A woman was killed when her car struck a truck that had pulled out in front of her. She was only 44 years old. The driver of the car failed to slow down and check for oncoming traffic.