Radio frequency highway management system

Details Radio frequency highway management system Radio frequency highway management system

2000-03-16

2001-02-20

Wu, Daniel J. (Department: 2736)

Communications: electrical

External condition vehicle-mounted indicator or alarm

Highway information

C340S928000, C235S384000, C701S117000

Reexamination Certificate

active

06191705

ABSTRACT:

FIELD OF THE INVENTION
This invention relates to traffic management and monitoring.
BACKGROUND OF THE ART
This invention has its principal application in the environs of an extent of highway planned for radio frequency (RF) toll collection where a substantial number of motor vehicles are equipped with transponders for communication with a roadside RF system for the assessment of tolls. Such transponders are called “normal transponders” herein to distinguish from what are called monitor transponders herein which assist in traffic management and monitoring.
The principles of automatic RF highway toll collection are discussed in the following patents:
U.S. Pat. No. 4,104,630 August 1978 Chasek
U.S. Pat. No. 4,303,904 Dec. 1, 1981 Chasek
U.S. Pat. No. 4,870,419 Sep. 26, 1989 Baldwin et al
U.S. Pat. No. 4,937,581 Jun. 26, 1990 Baldwin et al
U.S. Pat. No. 5,132,687 Jul. 21, 1992 Baldwin et al
U.S. Pat. No. 5,164,732 Nov. 17, 1992 Brockelsby et al
U.S. Pat. No. 5,192,954 Mar. 9, 1993 Brockelsby et al
U.S. Pat. No. 5,196,846 Mar. 23, 1993 Brockelsby et al
U.S. Pat. No. 5,289,183 Feb. 22, 1994 Hassett et al
The transponder which communicates with a roadside RF system customarily carries memory having such data characteristics as: transponder ID, vehicle class, revenue types, ownership, status of account, place of entry to or exit from a toll highway. The list of data characteristics may vary with different toll environments. However many of the above characteristics and others not mentioned may be desired by the local (as distinct from the overall) traffic authority for traffic monitoring or management or enforcement.
In some jurisdictions, a working transponder may be required by law for commercial vehicles, and optional, or not at all, for vehicles of other classes. In the latter case the enforcement procedures will only be employed for commercial vehicles.
Other requirements may be chosen by particular jurisdictions.
On a toll highway, a ramp, entrance or exit will have a highway extent often called a communications zone where the transponder may be written to or read from, by a reader which is located near the communications zones usually by the roadside or on an overhead gantry. Thus the communications zones must be within the transmission range of the reader and transponder.
The reader is that part of a roadside RF system which normally writes to or reads from a transponder in the communications zone.
In normal toll operations, a transmitter associated with the reader, located near the communications zone emits a periodic RF signal intended to activate the circuitry of any transponder in the communications zone. Transponders so activated in the communications zone call the reader at random. However both the reader and transponder are subject to a protocol which ensures that the reader communicates with only one such transponder at a time.
The normal transponder stores data which will typically include: public and private identification of the owner, last previous point of entry or exit, class of vehicle, status of account, etc.
When interrogated by the reader, the normal transponder will typically be programmed to release all or some of such information to the reader.
Upon the issuance of a “write” command to a normal transponder by RF signal from the reader, the data in the normal transponder may be changed, with the exception of identification information, which is only altered at special stations.
The reader may communicate at roadside with a passing transponder to extract information from the transponder as to last recorded location and add to it or replace it with the present location.
The “last recorded address” will usually be the address of entrance of the transponder-carrying vehicle into the highway system while the present address will normally be the address of leaving. Such addresses are of course used for toll calculation.
SUMMARY OF THE INVENTION
A transponder is used in accord with the present invention for traffic management or monitoring of traffic or for some enforcement purposes, such as the enforcement of the requirement that a commercial vehicle carry a transponder. The transponder used for one of the purposes outlined herein is spoken of herein as a monitor transponder to distinguish from transponders carried by the toll paying users. The latter transponders are referred to as normal transponders.
“The roadside RF system” is the term here used for the overall coordinated software for communication contemporaneously with a number of vehicle-borne transponders. The roadside RF system includes the reader which communicates directly with a normal transponder during a toll transaction.
A monitor transponder may be physically identical to a normal transponder. However, although such physical identity makes it usable for normal toll transactions, its usual extended stay within RF range of the communications zone, is used by the roadside RF system to determine (after consultation of the list of monitor transponder identifications) that it is a monitor transponder. The roadside RF system noting the extended stay of the monitor transponder in the communications zone then places the monitor transponder in “monitor” mode and purges it from the “present” list so that it is no longer polled by the reader. The roadside RF system filters the data received by the reader to pick out those transponders with the desired criteria. For example if the criterion is whether or not the transponder is a commercial vehicle, then the polling of such a commercial vehicle will actuate the roadside RF system to send a signal to a monitor transponder to cause it to make a sensible signal.
By “sensible signal” is meant a visible or audible signal. The sensible signal alerts the driver of the traffic authority or enforcement car (or the other custodian of the monitor transponder,) to check the commercial vehicle, the timing of the signal created by the radio RF system being chosen so that the subject vehicle is near a selected position (usually at the point of exit from the communications zone).
Thus in the case of the enforcement of the law that a commercial vehicle must carry a transponder, if the official at the monitor transponder sees a commercial vehicle, and the sensible indicator on the monitor transponder indicates that the criteria have been met, then the subject commercial vehicle is allowed to go on uninterrupted. If there is no sensible indication from the monitor transponder when a commercial vehicle is in the selected position, then enforcement procedures may be brought into place. In the usual course an official vehicle (usually other than the one with the monitor transponder) will pursue and pull over the commercial vehicle to determine whether it has a defective transponder or none at all.
If, at the time of the sensible indication in the monitor transponder, there are two commercial vehicles in the communications zone, the results are ambiguous, in which case it may be necessary to wait until the vehicles arrive at another monitored communications zone in the highway toll system.
The criteria could be changed, e.g. limited to commercial vehicles with accounts in good standing or with sufficient credit balance and a sufficiently charged transponder battery. In such cases, the sensible indication will not be given if any of these criteria is not met.
Criteria may be used which do not include the commercial vehicle. However unless there is a visual difference in the vehicles to be checked, it will not be possible to associate the sensible signal with a specific vehicle. However the sensible signal serves to provide an indication that a vehicle having a particular characteristic has passed the monitoring point. The sensible indication (usually beep or light) from a monitor transponder, may also usefully provide a count of vehicles registered as non revenue class, number of vehicles entering at a specific toll location, vehicles registered with a specific toll agency, etc.
The roadside RF system is responsive to the detection in the communications zone of a transponder with th

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