Apparatus for measuring moving state of vehicle in tunnel

An apparatus for measuring a moving state of a vehicle in a tunnel, the tunnel having an illumination light source installed therein, illumination brightness of the illumination light source being adjusted by an externally applied brightness/darkness adjustment signal, said apparatus comprising:

• image pickup means, installed in the tunnel, for generating image data of the vehicle;
• image processing means for processing the image data to determine a state of the vehicle, said image processing means comprising memory means for storing a plurality of background data sets of said tunnel in accordance with various possible brightness/darkness adjustment signals;
• input means for receiving said externally applied brightness/darkness adjustment signal;
• and
• adjusting means for adjusting data generating operation of said image pickup means or data processing operation of said image processing means in dependence upon said brightness/darkness adjustment signal, said adjustment means selecting one of the stored data sets in accordance with said brightness/darkness adjustment signal received by said input means.