Get the nearest node number\index in question for the location in question (or the exact segment number\idx directly would be better\easier), enum though the node's segment list (up to 8) for each segment you can query m_trafficDensity (0-255) or m_trafficBuffer(0-65535) assuming you know which segment is the one you are looking for, or you can just add them up for the whole node. I forget which one holds what exactly, I think Density was more related to the color status in the infoManager, and the Buffer was actual number of vehicles currently 'buffered' on said segment.