Tire marks are probably the most often confused and misinterpreted of all roadway evidence. A tire mark is the general class of marks left by a tire, whether rolling or locked. A skid mark is left by a locked, sliding tire.
There are different types of tire marks associated with a traffic accident investigation. The most common a private investigator will observe are:
Skid marks are further identified in the following ways:
The proper identification of tire marks is an important part of an accident investigation. Each tire mark is produced by a specific action of the vehicle during the traffic accident event. Tire marks can tell the private investigator about what a driver did or attempted to do prior to and after a collision. A point-of-impact (POI) or an area-of-impact (AOI) can determined which is an extremely important part of the traffic accident investigation.
The proper interpretation of tire marks can tell the private investigator which, of the many, speed calculation formula to be used. For example, a vehicle left a 150-foot tire mark on a paved roadway prior to running off the road. If the tire mark is identified as a yaw mark and the specific formula for that type of mark is used, a speed calculation of 48 mph is determined. That same mark if identified as a straight skid will yield a speed of 56 mph. An 8-mph difference may not mean much unless the posted speed limit is 40 mph.
Once in the realm of science fiction, it seemed incredible that a vehicle would be able to “see” other vehicles or pedestrians, anticipate collisions, automatically apply the brakes or take corrective steering actions and even drive itself. But this advanced technology is becoming increasingly available and more cars can do this to some degree.
Some of these systems have been around for a few years, mostly on high-end luxury cars. Collision-avoidance systems are getting better and are rapidly becoming a standard addition to new cars and not just a high-end option.
The Insurance Institute for Highway Safety (IIHS) has added collision-avoidance system testing to its suite of safety evaluations. They have determined that some of these collision-avoidance systems could prevent or mitigate many crashes. To win a top overall safety score, a car needs to have a forward-collision warning system with automatic braking and any autobrake system has to function effectively in formal track tests. To view the test results or to check if a vehicle has collision-avoidance systems available, visit the IIHS website at: www.iihs.org/iihs/ratings/crash-avoidance-features.
National Highway Traffic Safety Administration (NHTSA) is considering making some collision-avoidance systems mandatory. NHTSA’s 5-Star Safety Ratings note which systems are available on cars they crash-test but their presence doesn’t affect the rating. The cost of collision-avoidance systems can still be an obstacle with most advanced systems being part of a large options package or on a model’s higher, more expensive trim versions. The options can add thousands of dollars to a vehicle’s price.
Lasers, Radar, and Cameras
These active safety systems rely on numerous sensors, cameras, lasers, and short- and long-range radar which monitor what is going on around the vehicle. Other vehicles, pedestrians, cyclists, as well as the vehicle itself and even road signs are all monitored. Data is processed by computers, which then prompt an action from the car or the driver. These actions may start with attention-grabbers, such as a beep, a flashing dashboard icon, a tug from the seatbelt, or a vibration in the seat or steering wheel and if the driver doesn’t respond, the more advanced systems then apply partial or full braking force. Research has found that when a warning system emits too many inappropriate alerts, then there is temptation to switch it off.
Not every system on the market today is top-notch. But there’s a net benefit regardless. Even if the systems fail to prevent a crash, that crash is going to be less severe than it would have been otherwise. These systems can prevent crashes from happening in the first place.
Adaptive Cruise Control (ACC)
ACC allows the driver to select the cruise control speed and following gap. ACC detects if there is a vehicle in your path and either accelerate or brakes to maintain the selected following distance. If ACC cannot apply sufficient braking because of approaching a vehicle too rapidly, ACC will alert the driver.
Rear cross-traffic alert
Cross-traffic alert warns you of traffic approaching from the sides as you reverse. The warning usually consists of an audible chirp and a visual cue in either the outside mirror or the rear camera’s dash display. The more advanced systems can also pick out bicycles and pedestrians.
Forward-collision warning (FCW) and autobrake
Also called a pre-crash warning system, these systems warn drivers of an impending collision by using visual, auditory, or physical cues. Most vehicle systems also pre-charge the brakes and take other steps to prepare for impact. If the driver ignores the warnings, systems with autonomous braking, or autobrake, will apply partial or full braking force. They can be active at anywhere from walking to highway speeds.
Blind-spot monitoring (BSM) and assist
A blind-spot monitoring system uses radars or cameras to scan the areas beside and behind you, looking for vehicles entering or lurking in your blind zones. When such a vehicle is detected, an illuminated icon appears in or near the appropriate side-view mirror. If you signal a turn while a car is in your blind zone, some systems send a stronger alert, such as a blinking light or louder chirps. More advanced systems help keep you in your own lane by applying the
brakes on one side of the vehicle.
Pedestrian detection and braking
Pedestrian detection can recognize a person straying into a vehicle’s path. Some will automatically apply the brakes and newer systems can also detect bicyclists.
As you turn the steering wheel adaptive headlights will swivel, which helps illuminate the road when going around curves. Adaptive headlights improve a drivers’ reaction times by about a third of a second, just enough to avoid hitting a parked car or animal on a dark road.
Lane departure warning (LDW) and assist LDW
These systems use a camera, along with various sensors, to identify lane markers and monitor your distance from them. If you stray over the line without signaling, you’ll hear a warning tone, an LDW warning in the instrument panel or perhaps a physical alert like a vibration in the steering wheel or seat.
Lane departure warning does not provide a warning to help avoid a cash unless it detects the lane markings. More advanced “lane keeping assist” (LKA) systems selectively apply brakes or nudge the steering to guide you back if you’re wandering.
Automatic park assist
The system will identify a parallel or perpendicular parking space your car can fit into. Once found, the system steers the car into the space; some can also exit from parallel parking
spaces. The driver still does the braking and has to follow commands from the system.
Rear cameras and parking assist
Rear-view cameras will be mandatory with the 2018 model year. They can help prevent a back-over accident, such as hitting a child who wanders behind your car. Parking assist sensor systems notify you with progressively louder and quicker beeps as you close in on an obstacle.
Knowing what collision-avoidance systems a vehicle may have and what they are designed to do is within the realm of the private investigator. Due to the growing list of collision-avoidance systems the investigator must consider this advanced technology as part of their investigation. By researching the vehicle involved, the investigator can determine the type of systems a vehicle is equipped with. Understanding what the systems are designed to do can assist the investigator in discovering other factors involved in a traffic accident. These questions can become important for the client or the attorney.
Questions for the investigator to consider include:
The investigator can check the IIHS website: www.iihs.org/iihs/ratings/crash-avoidance-features or contact the local vehicle manufacture dealership to get information about the systems a vehicle may have and what they are supposed to do.
To schedule an appointment or find out more about the services we offer, please call 719 694-6343 or send us an email.
Or use our contact form.
Check out our articles for PI Now.
Our second article has been posted on PI Now. https://www.pinow.com/articles/2349/accident-investigations-vehicle-lamp-examinations
View our latest article on tire marks and their use in accident investigations at: https://www.pinow.com/articles/2399/tire-marks-their-role-in-accident-reconstruction-investigations