Light detection and ranging (lidar) is a high-resolution mapping tool currently used in self driving cars as well as for structure losses, tree/power line management, urban planning, engineering design, mapping planets, and in court litigation. Lidar uses an active sensor that emits an energy source (think the Death Star of “Star Wars” fame) rather than detecting energy from objects. Lidar is employed on the ground or in the air from airplanes, helicopters, and drones. It has become an essential tool when accuracy of measurements is critical for planning, designing, building, construction monitoring, or resolving location-related disputes scientifically. Let’s examine the technology’s advantages, disadvantages, its admissibility in court, and project examples.
Why Use Lidar?
Lidar data can be quickly collected, and the data is easy to retrieve and merge with photographs, video, images, and model elements. High sample density makes it more useful, as does the fact that it requires less people to operate than other methodologies. Lidar is not impacted by weather, and it can map featureless and inaccessible areas. It has been used forensically in wildland fire origin investigation, explosion sites, construction, standard of care/defect/as-built analyses, volumetric discrepancies, catastrophic injury, wrongful death investigation, and in the preparation of animations, fly-throughs, and courtroom demonstrative exhibits.
Lidar recently gained wider usage as a prevention tool in industries where catastrophic failures occur. As a result of the Northeast blackout in 2003 in which 50 million people in the U.S. and Canada lost power, the North American Electric Reliability Corporation was formed in an effort to determine the cause and to make recommendations to prevent future ones. Many thousands of miles of overhead transmission circuits and surrounding vegetation were surveyed by means of airborne lidar from which right of way and vegetation management policies and criteria have since been established.
With massive destruction caused by wildfires, some utilities have employed lidar corridor surveys as part of vegetation management programs. These programs seek to mitigate risk of fires caused by trees coming into contact with power lines. Lidar data is compiled with data to assess tree grown-in and fall-in risk that could result in power lines potentially causing a wildfire. That data is compiled so inspections of the identified trees can be scheduled and completed by vegetation management personnel. An overview of one such program is described in the Butte Fire Cases (2018) 24 Cal.App.5th 1150, 1164-1165.
No technology is perfect, though. Disadvantages of lidar include higher costs for some applications, need for skilled personnel to analyze data, and the fact that heavy rain or low-hanging clouds may impact results.
Admissibility Issues
As with any scientific evidence, getting lidar admitted in court requires preparation to overcome any challenges by the opposing party to the veracity of the data results. A California trial judge plays a “gate keeping” role on what evidence gets before the trier of fact, which is traditionally a jury. An insurer needs to make sure the theory of lidar and lidar instruments are generally accepted. Many times, the opposing party will not dispute the lidar data’s accuracy, but will argue through its own experts that the data does not support the conclusions of the opposing expert based on their subjective use of that data. Hence, the parties may stipulate that the lidar data itself is admissible in court, but fight over the interpretation and meaning.
A trial judge can take judicial notice of undisputed matters; otherwise, experts will be needed to lay the foundation that the theory is generally accepted as valid, trustworthy, and reliable in science, and that empirical studies validate the theory behind lidar.
In federal courts, scientific evidence must comply with Federal Rules of Evidence 702 and the Supreme Court opinion in Daubert v. Merrell Dos Pharms. Inc., which established a two-prong test for admissibility of expert evidence. The trial court must determine if the expert’s testimony “both rests on a reliable foundation and is relevant to the task at hand.” The court considers the methodologies if they can be tested, whether theories have been peer-reviewed and published; existence of standards governing the technique; any known or potential rate of error; and acceptance of the methodologies within the scientific or technical community. The trial judge has considerable leeway in determining if the testimony is reliable. Also, relevance must exist between the proffered testimony and the issue for consideration and resolution.
Lidar can put the jury or investigator in the physical location and perspective of a witness’s eye. It can provide real-world orientation and perspective to photographs taken by witnesses and first responders, which often times provide pivotal information.
Lidar in Action
As an example of the way lidar can be used, let’s look at a wildfire in Siskiyou County, California, which was determined to have been caused by electrical line slap during a high wind event.
At the time of the investigation, first responders noticed that the center conductor was untethered (also referred to as a “floater” in fire investigation terminology). During the latter part of the investigaton, lidar was employed to observe the location of the suspect conductor in both tethered and untethered states, from which demonstrative exhibits were generated (see Exhibit One).
Another use of lidar occurred in the fire and cause investigation of the Bastrop Fire Complex, which took place in central Texas in 2011. A tree was suspected of falling into an overhead circuit during a high wind event. However, the tree was removed from the scene prior to the completion of the forensic investigation. Terrestrial and airborne lidar were employed and integrated with terrestrial photogrammetry to reestablish the location and vegetation conditions surrounding the subject tree prior to the occurring fire.
Lastly is an example of reconstructing a subject tree to its pre-incident position following a fire in Napa County, California. The top portion of the subject tree was laying on the ground at the time of the lidar survey. The break points on the standing tree base and the top of the fallen subject tree on the ground were observed with lidar. The top of the tree was then placed back on the base, and exhibits generated from the survey showed the approximate position of the tree prior to the incident and the positional relationship between the tree and the statutory clearances from the electrical conductors.
Recommendations for Lidar
Once the use of lidar technology is identified as necessary, immediate retention of qualified experts is recommended. Similar to other claims, evidence preservation and documentation needs to commence immediately. Access demands to third parties in control of critical evidence should be completed, and video/audio recordings of witnesses should be done as quickly as possible. Claims professionals, lidar experts, and counsel must collaborate to prepare, plan, and execute to get the lidar survey completed in order to be successful.