Background

At 4:36 P.M. EST on Saturday, May 7, 2016, a 2015 Tesla Model S 70D car traveling eastbound of US Highway 27A (US-27A) near mile marker 29 in Levy County, west of Williston, Florida, struck the right side of a 2003 Utility 3000R refrigerated semitrailer, which was being towed by a 2014 Freightliner Cascadia truck-tractor.  At the time of the collision, the truck was making a left turn from westbound US-27A across the two eastbound travel lanes onto NE 140th Court, a local paved road.  After initial impact, the Tesla passed underneath the semitrailer, shearing off the car’s roof.  The Tesla continued off the right side of the road at a shallow angle, through a drainage culvert and two wire fences.  It then struck and broke a utility pole, rotated counterclockwise and came to rest perpendicular to the highway in the front yard of a private residence.  Overall, the Tesla traveled about 910 feet after striking the semitrailer.  The driver, who was the sole occupant died in the crash.[1]

Introtech Accident Reconstruction Services

James Crawford of Introtech was retained to perform an accident reconstruction on behalf of the driver’s family.  Mr. Crawford, who is an accredited accident reconstructionist and holds a B.S. in electrical engineering and M.S. in Aeronautical Engineering, provided an analysis of the Tesla’s sensors with their capabilities and limitations. Mr. Crawford analyzed the event data from the Tesla’s Autopilot suite which was in operation at the time of the crash.

“Autopilot” is a proprietary name used by Tesla for a combination of vehicle automation systems that provide driver assistance. The car is also equipped with a forward collision warning (FCW) system and automatic emergency braking (AEB), but those systems did not activate.

Mr. Crawford personally inspected the Tesla and the semitrailer that it struck. He documented damage on both vehicles with forensic measurements, notes and digital images and video.

Using data from Mr. Crawford’s research and inspections along with measurements taken by the Florida Highway Patrol, Mr. Crawford prepared a scale drawing of the crash scene. He used the scale drawing along with the data from the Tesla’s Autopilot system and the Freightliner’s Engine Control Module (ECM) to as key inputs to his reconstruction of this crash.

Analysis

System performance data indicated that the vehicle speed just before impact with the semitrailer was 74 mph. The highway has a posted speed limit of 65 mph. Driving at a speed of 9 mph over the posted speed limit, while improper, was not automatically unreasonable for the conditions that existed at the time of this crash. The NTSB ultimately came to the same conclusions as the Introtech reconstruction:

  1. There was sufficient sight distance to afford time for either the truck driver or the car driver to have acted to prevent this crash.
  2. This version of Tesla’s automated vehicle control system was not designed to, and did not, identify the truck crossing the car’s path or recognize the impending crash. Therefore, the Autopilot system did not reduce the car’s velocity, the forward collision warning system did not provide an alert, and the automatic emergency braking did not activate.
  3. The cause of this accident was the truck driver’s failure to yield the right of way to the Tesla, combined with the Tesla driver’s lack of reaction to the presence of the truck, likely because of an overreliance on the Tesla’s automation systems.

[1] NTSB Summary