On a training course recently one of the trainees described a situation where they were attempting to hatch decibel 'contours' to create a noise map along national roads for an entire county.
When they tried this the AutoCAD hatching was too large for their PC to handle and continuously crashed. The decibel contours came in DWG format from the NRA. Also provided with the drawing was a shape file. Using the shape file to visualise the decibel range along the roads is a quicker and more efficient way of achieving the same result.
The following video shows how to connect to and stylise noise level shape files that come from the NRA in AutoCAD Civil 3D: