I am looking to find a sensor that will recognize a car coming up an underground driveway andgive an audible signal to people on sidewalk
Audible signal to be wireless
sensor can be hardwired
Several types of sensors could be used, depending upon you unique setting and budget. Among the various types of sensors to consider are motion detection, "electric eye" (light beam), laser, or magnetometer (detects a change in the magnetic flux when a large object, like a car, passes by). Again, depending upon the setting and budget, this can be done wirelessly or hardwired. There are numerous visual and audible devices that could alert passersby along a stretch of sidewalk. I can help you to locate the perfect products in the Grainger catalog if you can give more specific information.