Three Essential Elements of Understanding Assured Clear Distance Ahead or “ACDA”

You’re driving your car on a two lane highway in the right hand lane, and you observe the posted speed limit as 60 MPH. Looking at your speedometer you note that you’re reasonably matching the speed limit within 1-2 miles. For the most part traffic is flowing consistently and smoothly along with the posted speed, however after sometime you find yourself behind someone traveling slower than the flow of traffic. You signal to switch lanes, but there’s not enough room to make the change. The person in front of you glances at their rearview mirror and sees you tailgating them. Meanwhile you haven’t slowed your vehicle to account for the drop in speed, either hoping the driver in front of you speeds up or you can make the lane change. The driver in front of you is growing agitated from your close proximity and performs a maneuver called the “break test.” Then crunch, you’re involved in a car accident. You’re convinced this accident is an act of road rage, but proving that you weren’t in violation of the common law -Assured Clear Distance Ahead (ACDA) is going to prove highly difficult. So what exactly is ACDA, and how can we better understand it to mitigate our liability in accidents.

  • First lets define what following too closely is. According to the US Federal Motor Carrier Safety following too closely is defined as “situations in which one vehicle is following another vehicle so closely that even if the following driver is attentive to the actions of the vehicle ahead he/she could not avoid a collision in the circumstance when the driver in front brakes suddenly.” So what is considered a safe distance?
  • A driver not maintaining an assured clear distance

    Generally a safe distance is defined in Massachusetts as minimally following the “two second Rule. The two second rule is defined in the MassRMV driving manual as “a minimum safe distance for good road conditions and moderate traffic. Pick an object in front of you, like a sign post or a tree. When the vehicle in front of you reaches that object, count out “one one-thousand, two one-thousand….. If you reach the object before you count two, you are too close. Slow down until you’ve put enough distance between you and the other vehicle.” A vehicle in front of you is considered a potential hazard, bringing us to the next essential part.

  • According to “Section 2-Driving Safely” of the Commercial Drivers License Manual 2005 from the United States Department of Transportation “You should always be able to stop within the distance you can see ahead.” This includes visible hazards or potential hazards one must anticipate, such as rounding a sharp turn, accounting for the fact there may in fact be another vehicle out of your line of sight.

All of those elements come together to help give an understanding of what is considered Assured Clear Distance Ahead or ACDA while behind the wheel of a car. Executing an understanding of these elements may help you potentially mitigate liability in a car accident. While “sudden emergencies” are an exception to the rule requiring motorists maintain an assured clear distance, having and executing an understanding of the elements of ACDA will help in a sudden emergency defense.

If you, or a loved one who has been injured in an automobile accident or sudden emergency automobile accident you may have options for obtaining compensation. Plymouth County personal injury law attorney Michael S. Mehrmann has spent many years helping people from across Plymouth County, including in Kingston, Plymouth, Marshfield, Hanson, Carver, Pembroke, and Duxbury, deal with their legal needs. To find out more about how we can assist you, call (781) 585-3911 or contact us online.