Variable speed limit system

• US 6,825,778 B2
• Filed: 10/21/2002
• Issued: 11/30/2004
• Est. Priority Date: 10/21/2002
• Status: Active Grant

• Current Assignee: International Road Dynamics Incorporated (Quarterhill Inc. (f/k/a Wi-LAN Inc.))
• Original Assignee: International Road Dynamics Incorporated (Quarterhill Inc. (f/k/a Wi-LAN Inc.))
• Inventors: Bushman, Robert, Bergan, Terry
• Primary Examiner(s): LA, ANH V
• Application Number:
  US10/274,042
• Publication Number:
  US 20040075582A1
• Time in Patent Office: 771 Days
• Field of Search: 340/905, 340/903, 340/901, 340/936, 340/438, 340/441
• US Class Current: 340/936
• CPC Class Codes: G08G 1/01 Detecting movement of traffic to be counted or controlled G08G1/07 - G08G1/14 take precedence

Abstract

A variable speed limit work zone safety system is provided herein. It includes at least two spaced-apart stations. Each station includes a plurality of sensors to gather information relative to at least one of traffic flow and road conditions. The station includes a controller which is programmed to analyse data which is received from the sensors and to derive, therefrom, an optimum speed limit at a selected location adjacent to, or in, the work zone. The station further includes a communication sub-system to communicate data related to the optimum speed limit to a message board to display the optimum speed to motorists.

Claims

1. A variable speed limit system controller for communicating with a traffic station to determine a speed limit based upon input provided by a sensor in the station, and with a display for displaying a variable speed limit, the controller comprising:

an input for receiving information related to lane occupancy and at least one of traffic flow, road conditions, vehicle speed, vehicle presence and weather conditions, from the sensor;

an output for transmitting a derived speed limit to the display; and

a processor for receiving the information from the input, for determining the derived speed limit for a region adjacent to the station, based on the received information, and for providing the derived speed limit to the output for transmission to the display.

2. The variable speed limit system controller of claim 1, wherein the processor includes means for inversely varying the speed limit in accordance with lane occupancy information.

3. The variable speed limit system controller of claim 1, wherein the input includes means for receiving information from a plurality of sensors located in a plurality of stations spaced apart from each other.

4. The variable speed limit system controller of claim 3, wherein the processor includes means for deriving a speed limit for each station, based on the information received from the sensors located in each station.

5. The variable speed limit system controller of claim 4, wherein the output includes means for transmitting the plurality of derived speed limits to a corresponding plurality of displays.

6. The variable speed limit system controller of claim 1, wherein the output includes means for transmitting the derived speed limit to the display using a wireless communications channel.

7. The variable speed limit system controller of claim 6, wherein the wireless communications channel is an RF communications channel.

8. The variable speed limit system controller of claim 1, wherein the processor includes means to derive a text based message, for transmission to the display by the output, the message derived using the information received from the input.

9. The variable speed limit system controller of claim 8, wherein the display includes means for displaying the derived text based message in addition to the derived speed limit.

10. The variable speed limit system controller of claim 1, wherein the output includes a wireless modem to transmit output signals to a monitoring station.

11. The variable speed limit system controller of claim 10, wherein the wireless modem is a cellular communications modem.

12. The variable speed limit system controller of claim 10, wherein the monitoring station is selected from a list including a personal computer and a pager.

13. The variable speed limit system controller of claim 1, wherein the sensor is selected from a list including active radar sensors, passive acoustic sensors, ultrasonic sensors, pneumatic road hoses, tape switches, piezoelectric sensors, fibre optic sensors, quartz sensors, active magnetic devices, inductive loops, elongated elastomeric members having an elongated pressure sensor thereon, coaxial piezoelectric cables, flanged tube sensors with piezoelectric plates, and DYNAX™

sensors.

14. The variable speed limit system controller of claim 1, further including means for connecting a power supply to provide power to the input, the output, and the processor.

15. The variable speed limit system controller of claim 14, wherein the power supply includes a solar panel array.

16. The variable speed limit system controller of claim 1, wherein the processor includes means for determining the speed limit using a lookup table and the received information.

17. The variable speed limit system controller of claim 1 wherein the processor includes means for determining the speed limit using a lookup table, the received information, and time of day information.

18. The variable speed limit system controller of claim 1, further including a refresh engine for initiating a refresh of the derived speed by the processor.

19. The variable speed limit system controller of claim 18, wherein the refresh engine includes means for initiating the refresh at fixed intervals.

20. The variable speed limit system controller of claim 18, wherein the refresh engine includes means for initiating the refresh at intervals determined by the received information.

21. The variable speed limit system controller of claim 1, wherein the processor includes means for manually overriding the derived speed limit, and for providing a static speed limit and text message to the display.

22. The variable speed limit system controller of claim 1, further including a self diagnosis engine for verifying that the operation of the input, the output and the processor are within predefined tolerances.

23. The variable speed limit system controller of claim 22, wherein the self diagnosis engine further includes means for entering a fail safe mode of operation when a component outside of the predefined tolerance is detected.

24. The variable speed limit system controller of claim 1, wherein the received information related to road conditions includes information regarding whether the road surface is dry, wet, icy or frost covered.

25. The variable speed limit system controller of claim 1, wherein the processor includes means for deriving general advisory messages based on the received information and for providing the derived general advisory messages to the output for transmission to the display.