OBJECTIVE – Check the impact that the placement of the traffic control equipment had on the driver’s line of sight by generating a three-dimensional digital environment and observing the sight line of the driver in two instances: (1) when the traffic control sign is positioned in such a way as can be seen in photographs, and; (2) when the traffic control sign has been moved further from the edge of the road.
In this example, a 3D scan was conducted of the intersection at King Edward Avenue and Cartier Street in Vancouver BC. Because the scene was scanned at a later time than when the photographs were taken, the traffic control sign and hazard signs that were present when the accident occurred were unavailable at the time of the scan.
Above: video flythrough of scanned environment.
Once the scene has been scanned, detailed spatial information can be extracted from the scan data as needed in a variety of formats which can readily be imported into an engineer’s technical software to assist with analysis. Scan data can also provide new or additional measurements, or verify the accuracy of an engineer’s initial measurements.
In some cases it may not even be necessary to send an engineer to visit the site at all. The scan data is performed independently of opinion analysis and can be referred to various experts for analysis.
In this example, the topography of the road was exported for an engineer’s analysis. The profile of the road was reconstructed in 5 meter intervals, providing a highly precise surface for the engineer to input into accident reconstruction software, ex. PC-Crash. As a result, the engineer was able to verify the accuracy of his initial measurements against the scan data and evaluate his analysis accordingly.
Above: Traffic control sign was reconstructed and placed into the digital environment to match what was observed in the photographs.
This technique is especially useful to explore and present visibility issues, as it enables the opportunity to “step into the scene” and view the scene from any perspective.
Above: Computer-generated models are imported and placed into the digital environment.
In this case, the objective was to find out if the placement of the traffic control equipment had an impact on the sightline of the driver. The images below compare the driver’s line of sight in two instances: first, when the traffic control sign is positioned in such a way as can be seen in photographs; and second, when the traffic control sign has been moved approximately one metre inwards from the edge of the road.
Below: Two images comparing the driver’s line of sight.