Case overview

Case Overview

A city bus making a right turn at an intersection collided with and seriously injured a pedestrian crossing the street. The accident raised many questions concerning the behavior of both the pedestrian and the bus driver. Was the pedestrian in the crosswalk? Was she visible to the bus driver? Had she seen the bus before starting to cross the street?

Data regarding the accident was available in the form of post-accident photographs, distant surveillance videos, bus “black box” data, witness statements, and the police accident report. Each of these told a portion of the story, but the overall picture was incomplete and left many questions. Our reconstruction resulted from the synthesis of all these data sources and additional information we captured through accident scene laser-scanning and geometry measurement, photogrammetry and videogrammetry, vehicle testing, physics-based computer simulation of vehicle motion, and painstaking analysis. When the bus moved out of the field of view of one of the surveillance videos, we even analyzed its shadow to determine its position.

As a result, we were able to reconstruct the positions of both the bus and pedestrian in the seconds prior to their collision with high confidence and gain great insight into how the accident occurred. To help illustrate these results, we created a 3D animation of the accident. Our team was fully prepared to present the results to a jury at trial, but the case was resolved before this could happen.