Who Crossed the Centerline?

This incident involved a school bus traveling westbound and a tractor traveling eastbound on a non-divided, two-lane roadway. The front left of the school bus was contacted by a farm implement which was being towed by the tractor. The collision occurred just beyond the crest of a hill. ARCCA’s accident reconstruction team was tasked with determining which vehicle crossed into the opposing lane of travel.

Steps Taken:

  • Reviewed the available materials including police report, scene and vehicle photographs, and statements from the involved parties.
  • Inspected the site and the involved vehicles using photographs, measurements, and three-dimensional laser scanning to document roadway markings and damage profiles.
  • Performed a sight-line analysis to understand what the driver of each vehicle could see while driving through the incident location.
  • ARCCA’s team of animators was able to illustrate an accurate animated depiction of the incident using evidence from the scene. These animations can be viewed in the videos below.

Roadway evidence, including gouge marks from the chisel and tire marks from the bus, was captured at the scene.

Final Findings:

  • Roadway evidence, along with an understanding of the damage location on each impacted vehicle, helped us conclude that the towed farm chisel pulled by the tractor encroached upon the school bus’ lane of travel.
  • Based upon the roadway geometry, the bus driver was unable to see the tractor and towed chisel before cresting the hill, and had no time to react.

Mock up of bus and tractor before collision

Scene illustration of the impact using 3-D laser scans of the incident site, subject tractor and chisel, and an exemplar bus.