Sensor Intervals Each type of sensor used along the BorderTransportationSystem will be selected to have the broadest span and range available.   Most of the sensors will be effective at 500 feet or more, but some may not be, and thus each will have to be selected for the use and coverage  within a cost range.  The following are general ideas, specifications, and installs for various types of sensors.  There will be many different types used on the system and these are TBD at a later date. Index of ... Fiber Optical sensors for High-speed rail applications Reliable sensors for rail vehicles Sensing and Sensors - MIT