2006-09-21 04:09:27 · 5 answers · asked by teetu s 1 in Science & Mathematics ➔ Engineering
United States Patent 5735491
http://www.freepatentsonline.com/5735491.html
Abstract: An apparatus for detecting the presence of an approaching train, includes a warning indicator, a receiver for receiving a brake system status signal transmitted from an approaching train, and a relay for coupling a voltage potential to the warning indicator when the brake system status signal is received by the receiver, wherein the warning indicator, the receiver and the relay are positioned within a passenger vehicle. Also there is a method for detecting the presence of an approaching train by detecting a brake system status signal originating from the train.
2006-09-21 04:13:55 · answer #1 · answered by missourim43 6 · 0⤊ 0⤋
Proximity sensors placed along the tracks. Put these sensors out of your range of sight. Once the train passes the sensor, it will send a signal back to you through a beep or a light to let you know a train is approaching. You can have multiple sensors also to help calculate the rate of speed based on knowing the distance between the sensors and how long it takes the train to trip them.
2006-09-21 04:15:28 · answer #2 · answered by Anonymous · 0⤊ 0⤋
The Doppler Effect.
2006-09-21 04:17:54 · answer #3 · answered by Aria 4 · 0⤊ 0⤋
a seismograph on the tracks possibly? You'd just have know what to look for since cars could cause a disturbance too.
2006-09-21 04:13:52 · answer #4 · answered by Sean H 2 · 0⤊ 0⤋
Hi. Your ears.
2006-09-21 04:14:21 · answer #5 · answered by Cirric 7 · 0⤊ 0⤋