Wireless railroad grade crossing warning system

• US 5,864,304 A
• Filed: 08/08/1996
• Issued: 01/26/1999
• Est. Priority Date: 08/08/1996
• Status: Expired due to Term

• Current Assignee: AT&T Corporation (AT&T, Inc.)
• Original Assignee: AT&T Corporation (AT&T, Inc.)
• Inventors: Shen, Thomas T., Gerszberg, Irwin
• Primary Examiner(s): Hofsass, Jeffery A.
• Assistant Examiner(s): TWEEL JR, JOHN ALEXANDER
• Application Number:
  US08/694,378
• Time in Patent Office: 901 Days
• Field of Search: 340/903, 340/907, 340/902, 340/905, 340/901, 340/989, 340/994, 49/25, 49/49, 246/473.1, 246/473.2, 246/473.3, 246/122 R, 246/187 B, 246/293, 246/125, 246/126, 246/127, 246/5, 246/7
• US Class Current: 340/903
• CPC Class Codes: B61L 29/18 Operation by approaching rail vehicle or train
• CPC Class Codes: B61L 29/28 electrically operated

Abstract

A railroad-crossing warning system for protecting pedestrians and motorists from an oncoming train. The warning system has a vehicle detector system for determining whether a vehicle is stuck in an area of the railroad crossing, a train detector system for determining vital train information including the speed and direction of the oncoming train, a display unit for displaying warning messages to the pedestrians and motorists approaching the railroad crossing, and a communication system for communicating the vital train information and the distressed vehicle information to the oncoming train and the display system. The system provides early warning to the operator of the oncoming train to provide more reliable protection for distressed vehicles in the railroad crossing and for motorists and pedestrians approaching the railroad crossing.

Claims

1. A railroad crossing warning system for protecting traffic from an approaching train, comprising:

a wireless trackside communications system for bidirectionally communicating critical railway and traffic control data, between a vehicle at a railroad crossing and a train approaching the railroad crossing, said wireless trackside communications system having a plurality of trackside devices for detecting the presence, location, speed and direction of the approaching train to determine train warning information, said plurality of trackside devices communicating said train warning information between each other;

a vehicle detector system operating independently of any onboard vehicle systems, the vehicle detector located at the railroad crossing for detecting a presence of a vehicle in an area of the railroad crossing;

said vehicle detector system coupled to a given trackside device of said wireless communications system such that said distressed vehicle warning information is communicated thereon; and

a display unit located at the railroad crossing for displaying said oncoming train warning information and said distressed vehicle warning information communicated on said wireless trackside communications system.

2. The warning system of claim 1 wherein said vehicle detector system comprises at least one sensor probe and a control box, said at least one sensor probe positioned within said given area of said railroad crossing for detecting the presence of vehicles therein, said control box coupled to said at least one sensor probe for monitoring said sensor probes to determine whether to send distressed vehicle warning information to said wireless trackside communications system.

3. The warning system of claim 2 wherein said at least one sensor probe uses a magnetic sensing technique to detect the presence of large metal objects.

4. The warning system of claim 3 wherein said at least one sensor probe is buried six to eight feet underground in the railroad crossing.

5. The warning system of claim 4 wherein said at least one sensor probe provides a given coverage range in the railroad crossing.

6. The warning system of claim 5 wherein said given coverage range in the railroad crossing is 40 feet squared.

7. The warning system of claim 2 comprising six sensor probes that provide a given coverage range in the railroad crossing area.

8. The warning system of claim 2 wherein each said sensor probe has an output coupled to said control box.

9. The warning system of claim 1 wherein each trackside device is coupled to the track through a track circuit which detects whether a train is present at a given time.

10. The warning system of claim 9 wherein said train detector system computes a speed on the approaching train through the following steps:

comparing said given time of consecutive trackside device train detections to determine an elapsed time therebetween;

identifying a distance between said consecutive trackside devices; and

dividing said distance by said elapsed time between said consecutive trackside devices to determine said approaching train speed.

11. The warning system of claim 10 wherein said display unit comprises a two-sided light emitting diode display for displaying warning messages.

12. The warning system of claim 11 wherein said warning messages include an unsafe vehicle detected in the railroad crossing message, a train approaching message, a train direction message, and a train approaching time message.

13. The warning system of claim 12 wherein said wireless trackside communications system employs a fast message hopping method for communicating said distressed vehicle warning information and said approaching train information.