For an alert , get a Dakota Alert system. Top quality and they just plain work.
There are pir detectors, but they pickup motion, including deer, dogs, and cats as well as people and cars.
The buried MAD sensor is the way to go. Buried parallel to the driveway, so no trenching under the driveway. Transmitter has a range of several hundred feet (do not remember the number) and has plenty of range for what you want.
The receiver can handle several transmitters, so you could add more buried detectors or motion detectors if you want.
The systems can also trigger lights , iirc.
There are pir detectors, but they pickup motion, including deer, dogs, and cats as well as people and cars.
The buried MAD sensor is the way to go. Buried parallel to the driveway, so no trenching under the driveway. Transmitter has a range of several hundred feet (do not remember the number) and has plenty of range for what you want.
The receiver can handle several transmitters, so you could add more buried detectors or motion detectors if you want.
The systems can also trigger lights , iirc.