TRAFFIC SIGNAL LIGHT CONTROL FOR EMERGENCY VEHICLES

Abstract: Apparatus to control road faring vehicle traffic in connection with emergency vehicle traffic. The problem of passing through busy street intersections represents a dangerous problem to both an emergency vehicle and to the general traffic at or in the vicinity of the intersection. To solve such a problem, a traffic light control system which includes two-way communications (13, 14, 16 and 17) between a moving emergency vehicle (1) approaching a busy intersection (ABCD) with one or more traffic lights (2), is arranged so that the traffic light control apparatus (62) has stored therein preset patterns of response (Fig. 7, 52a) that temporarily preempt the usual operation of the traffic light and instead provides the most effective method of routing the vehicle through the intersection while redirecting general traffic. As part of the invention, the traffic light control mechanism (62) returns acknowledgement of receipt of instructions to the emergency vehicle (Fig. 6, 89).

Description: TRAFFIC SIGNAL LIGHT CONTROL FOR EMERGENCY VEHICLES FIELD OF THE INVENTION The invention belongs to the field of traffic con- trols, and more specificially, to the control of road faring vehicle traffic in connection with emergency ve¬ hicle traffic. BACKGROUND OF THE INVENTION Whenever an emergency vehicle is traveling under con- ditions of urgency, the problem of passing through busy street intersections represents a dangerous problem to both the emergency vehicle and to the general traffic at or in the vicinity of the intersection. The problem has become especially severe -in recent years when many drivers travel in air conditioned cars with their windows rolled up and often with the radio turned on so that they may be unable to hear the siren of an approaching emergency ve¬ hicle. Many serious accidents happen each year as a re¬ sult of collisions between emergency vehicles and other traffic. In heavy city traffic there is. still another problem in relation to the travel of emergency vehicles. As an emergency vehicle approaches a busy intersection and some of the drivers respond to the siren and pull to the curb and halt, as required, busy intersections become filled with vehicles standing still and often completely • block the progress of the emergency vehicle. Many inven¬ tors have in the past sought to devise practical solutions to these problems. J.O.D. Shepherd, Patent No. 2,355,607 issued August, 1944 discloses a system providing radio transmitters mount¬ ed on emergency vehicles that radiate a signal that is de¬ tected by direction sensitive receivers at the traffic signals and sets the signals such as to admit the emer¬ gency vehicle. F.C. Campana et al, Patent No. 3,257,641 issued June 1966 also discloses a system where a vehicle-mounted radio transmitter sets traffic signals to a special emergency light condition that halts all other traffic. J.C. Lesher, Patent No. 3,247,482, issued April, 1966 discloses a system where an emergency vehicle-mounted radio transmitter broadcasts simultaneously two subcar¬ rier signals which prevent interference of two vehicles simultaneously attempting to control the traffic lights. Other inventors have disclosed systems that employ sonic or light microwave radio signals in order to con¬ trol the traffic lights. H.G. Malach ' , Patent No. 3,881,169, issued April 1975 discloses a system where each intersection has sonic re¬ ceivers tuned to certain sound frequencies transmitted by an approching emergency vehicle, so as to direct the traffic lights to guide the vehicle through the intersec¬ tion. L.L. Rose, Patent No. 4,016,532 issued April 1977 discloses a system in which an emergency vehicle mounted transmitter sends a coded signal to a receiver at the intersection where it causes the traffic signal at the intersection to turn to steady red in all directions. E. Elmasian, Patent No. 4,135,144, issued January 1979 discloses a system in which a radio transmitter mounted in the emergency vehicle causes a receiver at the signal to initiate a light signal sequence that causes the signal to first send flashing red in all directions before turning steady red in all directions. It appears that none of the systems of the prior art have completely solved the problem of coordinating and controlling traffic so as to accommodate an emergency ve¬ hicle in transit since none gained wide acceptance. The main problems, it has been found, reside in the fact that city intersections are often very complex in their physical layout and often several intersections are mutually interacting as heavy traffic flows from one traf¬ fic direction to another through such inter-related busy intersections. Additionally, the pattern of traffic flow often changes during the day, such that morning rush hour traffic is different from evening hour rush traffic. The present invention overcomes these problems by providing a two-way interactive encoded communications link between signal controls at an intersection and emer¬ gency vehicles, where vehicle-mounted communications ap- paratus transmits, from an approaching emergency vehicle, a digitally encoded message to communications and control apparatus associated with a single traffic intersection or with complicated groups of intersections, that trans¬ mits to the control apparatus the identity of the vehicle followed by the desired route through the intersection. The control apparatus at the intersection, in response, inserts the request into an electronic memory bank, re¬ siding at the control apparatus, or associated therewith, which in turn provides one of a number of preselected optimal patterns for that intersection, so that the traf¬ fic control quickly may clear all traffic lanes to be used by the emergency vehicle instead of blocking them with stalled traffic. The traffic control additionally returns a confirmation code to the emergency vehicle that tells the driver that his request has been received and that he can safely proceed through the intersection. SUMMARY OF THE INVENTION It. is a primary object of the invention to provide an emergency vehicle traffic control system that uses two- way communication links between emergency vehicles and traffic control apparatus at intersections such that en coded signals from the vehicle inform the control appara- tus of the desired route through the intersection, and wherein preselected optimal traffic signal patterns are stored in a memory bank to provide the best possible path for an emergency vehicle through that intersection. It is another important object to provide an emer¬ gency vehicle traffic control system that returns a re¬ sponse to the driver that confirms that his request has been received and is being executed by the signal control apparatus. It is still another important object to provide an emergency vehicle traffic control system that is adaptable to changing traffic conditions such as morning and evening rush hour traffic. It is still another important object to provide an emergency vehicle traffic control system that insures against interference between several vehicles operating within the same area at the same time. -It is still another object to provide an emergency vehicle traffic con _trol system that can use the two-way radio equipment already installed in the vehicle for the traffic light control. It is still another object to provide an emergency vehicle traffic control system that allows human inter¬ vention under unusual circumstances. Still other objectives and advantages will become clear in the course of the following detailed description with appended figures and claims. BRIEF DESCRIPTION OF THE FIGURES Figure la is a diagrammatic "birds-eye" view of an intersection with emergency traffic control, with an ap¬ proaching emergency vehicle and the communication links between them. Figure lb is a traffic light; Figure 2 is a diagrammatic "birds-eye" view of a complex intersection with several traffic signals and traffic patterns and linked traffic controls; Figure 3 is a diagram of a digitally encoded message format used with the invention; Figure 4 is a diagrammatic view of an emergency ve¬ hicle control console as used with the invention showing the major function blocks and their interconnections; and Figure 6 is a flow-chart diagram of the steps per- formed by the vehicle and the intersection control appara¬ tus in the execution of a request for transit. DETAILED DESCRIPTION In the following, a number of preferred embodiments of the invention have been described in detail in relation to the appended drawings. It is to be understood that the invention is capable of other embodiments that are obvious to those skilled in the art to which it pertains and there¬ fore fall within the scope of the invention. The terminology used therein is for description and not to be limiting. Wherever gender is used, the male gender is used to represent both genders. The term "driver" is used to represent the person or persons in the vehicle operating the"vehicle and the traf- fie control apparatus. Figure la is a "birds-eye" view of a simple inter¬ section consisting of four branches at generally right angles to one another. The branches are designated A, B, C, and D in clockwise direction with branch A pointing North. That convention is used throughout this specifica¬ tion to designate branches to intersections. A traffic signal 2 is suspended above the center of the intersection as is often used in relatively simple cases such as this. A signal control 62 located near the intersection com- prises the apparatus used in connection with the operation of the traffic signal, such as electrical relays with contacts to control the lights, power connections to the main ac-power source, and sequencing apparatus that con¬ trols the successive phases of traffic lights. The control also includes the traffic light emergency control apparatus in accordance with the present invention. Figure lb shows a conventional simple four-sided traffic signal as is commonly used. Each of its four sides has sectors consist¬ ing of a red light 18 at the top signalling approaching traffic to stop when facing the red light, a yellow signal 19 in the middle, warning that red is coming next and a green light 19 at the bottom signalling approaching traf¬ fic facing the green light permission to proceed. A fourth section 22 at the bottom showing a green arrow is at times used to indic e that left turn or other special condi¬ tions are permitted. At some locations multiple signals are located over divided traffic lanes to indicate dif¬ ferent turn modes for the different lanes of traffic. There is a great variety in the different ways traffic sig¬ nals are displayed in different localities, depending on local preferences and policies. It is not necessary to describe these differences in more detail, since the inven¬ tion is not directed to modes in which the signals are de¬ ployed per se, but to the methods used to select and de . - ploy the modes that are preferred in directing emergency vehicles through busy intersections. In Figure 1, as the emergency vehicle 1 approaches the intersection from the South on branch C, the driver has turned on his traffic control console shown in Figure 4 by operating its on-off switch 43 and the "power-on" light 44 indicates power is on. In accordance with the invention each vehicle authorized to operate in the area or jurisdic¬ tion of the particular intersection has a unique identity number, which may typically be a three digit number which has been dialed into the three dials generally at 45, con¬ sisting of the hundreds digit H, tens digit T and units digit U. These dials may, if merited, be placed under a locked cover and inaccessible to the operating personnel. An alpha-numeric keyboard 42 is used to first key in the identity number or designation code of the intersection being approached together with the branch of ingress to the intersection and the branch of egress requested. It is assumed that the driver has in his possession a chart that sho__ the identity number or code of the intersections in his area of jurisdiction or has memorized these designa¬ tions. It should be noted that all the designations could be allocated mnemonic codes as they are now widely used iri data systems in order to facilitate the use of the system. The details of coding is, however, immaterial to the inven¬ tive concept. As a result, the vehicle control apparatus 47 in Fig¬ ure 5 records the above information from the keyboard 42 and stores it in digital code in the data assembler 51. The data assembler prepares a small "packet" or record of information consisting of the characters keyed in and assembles them in a selected sequence so that it can be transmitted serially as a string of characters from the vehicle. The codes used for character transmission is im- material; the most generally used code is the so-called ASCII code which is described in textbooks on data trans¬ mission such as Computer Organization and Programming by William Gear, published by McGraw Hill Library of Congress Catalog No. ISBN 0-07-023076-5 and Digital Systems: Hard- ware Organization and Design by Frederick J. Hill et al published by John Wiley & Sons, Library of Congress No. ISBN 0-471-39605-2. Figure 3 shows the format of this information packet consisting of eleven numbered boxes, 1-11. Starting from right to left, box No. 11 represents the departing branch. Assuming the driver intends to leave at branch D after having made a left hand turn from C, it would contain a "D" in box 11 and a "C" in box 10. Assuming the intersec¬ tion has identity number 6789, these numerals would be stored in boxes No. 6 through 9. The vehicle identity number would be stored in boxes Nos. 3, 4 and 5. After the characters are assembled in the data assembler 51, a so- called check-sum may be computed by the data assembler. The check-sum is typically the number of "ones" (l's) in the assembled character string contained in the spaces 3 through 11 as they are converted to ASCII code. In the ASCII code format each character consists of an eight bit binary number, which is, again, a string of eight ones or zeroes (l's or 0's). After the character string has been assembled in the format shown in Figure 3, it is sent to a modulator 53 which modulates a tone frequency that is fre- quency keyed in two discrete frequencies to produce the ones and zeroes in accordance with industry standards. The modulator is part of a so-called modem which is typically a modulator-demodulator (MODEM) combined into one piece of hardware, with the demodulator 52. The modulator 53 will, when the data assembler 51 is ready, turn on the transmitter 56 which is a radio frequency generator pro¬ ducing a radio carrier in one of the frequency bands allo¬ cated for applications of this nature by the Federal Com¬ munications Commission (FCC) . The transmitter may now be frequency-shift keyed by the modulator and transmits the character string consisting of the 11 characters of Figure 3 preferably in the numbered sequence. Before transmitting its carrier, however, it is advantageous that * the modulator waits until it has checked to see if the radio frequency used is available; in other words, if no other vehicle or traffic signal is currently using the same assigned radio frequency. This function is performed by the demodulator 52 which receives the radio carrier signal from the re¬ ceiver 54, if the frequency is in use. It should be under- stood that preferably, the invention uses the same frequency for transmissions from vehicle to signal and vice versa. Assuming the frequency is available, at that moment the transmitter will turn on the carrier frequency which could, typically, be in the 180 megaherz range. The transmitter will be modulated in rapid succession by the one's and zero's of the character string of Figure 3, which with 11 characters each with 8 bits represent 88 bits. The transmitter will typically operate in the frequency modu¬ lation mode so that the frequency modulated audio signal from the modulator operates to frequency-shift modulate the radio carrier produced by the transmitter. The transmitter is connected ' to an antenna 57 mounted on the vehicle, and transmits the character string to the distant antenna 61 located at the intersection signal control 62, where it is received by the receiver 64. As soon as the message is transmitted, the transmitter at the vehicle turns off its carrier. The transmission may typically take a small frac¬ tion of a second at a carrier frequency above 30 megaherz. The signal control apparatus at the intersection hav¬ ing now received the request from the emergency vehicle with the information containing the identity of the ve- hide and the driver's path of transit through intersection proceeds to execute the request. The dashed -line box 62 of Figure 5 shows the major function blocks of the signal control apparatus. The re¬ ceiver 64, already mentioned, sends the received character string of 88 characters through the demodulator part (DEM) 74 of a modem 74, 73, also containing the modulator 73 (MOD). The modem here performs a function that is similar to that of the modem 52, 53 in the vehicle control 47. The digital, binary character string produced by the demodula- tor is sent to a bus interface (BUS IF) 75 which communi¬ cates with a digital bus 80 which is, in turn, a part of a micro-processor control system consisting of the central processing unit (CPU) 69, the read-only memory (ROM) 66, the random access memory (RAM) 67 and a maintenance test unit (MA-TE) 68 and the electronically alterable ROM, the EROM 70. Microprocessor systems contain a microprocessor unit (CPU) that is connected with memory sections. The memory sections contain all control programs in binary coded num- bers. Each memory section consists of memory cells, each of which may exist in two states, namely as a "one" (1) or a "zero" (0), also designated "on" or "off", respec¬ tively. The ROM memory 66 contains, in stored digitally encoded form, the control programs which constitute the control functions for the control system. The RAM memory 67 contains transitory information which the CPU requires in order to perform its operations. The control programs in memory are sub-divided into smaller sub-sections or modules, each having discrete, defined functions within the entire blanking system. Figure 7 shows the more sig¬ nificant sub-sections of the control program and is de- scribed in greater detail below. The control programs consist of sequentially numbered listings of digitally encoded instructions that are stored in the memory. The instruction format and encoding is part of the instruction set which is again a part of the structure of the microprocessor, as originally established by the designer of the microcomputer. The control programs, acting through the hardware of the microprocessor, are capable of operating on and .monitoring other sections of hardware which are part of the entire control system. The ROM 66 contains the control programs that rarely change. The RAM 67 contains program information that is transitory and changes frequently. The maintenance-test unit 68 MA-TE contains Programs and hardware that monitor -the operation of the system and produces an alarmthat may » be transmitted to a remote, attended location if equipment malfunctions are detected. The lights in the signal 2 are operated by a regular signal control 71 which performs the continuous, periodic sequencing of the lights during normal traffic conditions. it may contain conventional hard-wired logic components, as in most older systems, or it may be controlled by the CPU 69 over the bus 80 as in newer systems. Whichever me¬ thod of operation is used for this function is immaterial in view of the invention. An emergency signal control 72 takes over the light control in case an emergency vehicle request is being exe¬ cuted by the signal control, and is, for this purpose, connected to the CPU bus 74. In this case, the operation of the regular signal control 71 is pre-empted. The operation of the signal control 62 is shown in functional steps in the flow chart of Figure 6, which traces the steps in the execution of an emergency request. The symbols of the flow chart are conventional and standard and are described in reference books on control systems, as in aforesaid referenced sources. The first step 76 is the request for an emergency transit through the intersection. The next step is the decision point 77. If the signal control 62 is engaged in the execution of a request from another emergency vehicle a "WAIT" message 96 will be sent back to the vehicle through the NO branch at 77. If the signal con- trol is ready to execute the request, the next step 78 is to interpret the information in the received request message. As part of the interpretation, the validity of the request message is checked including the validity of the vehicle identity number. Next the time of the day- is noted in step 79 and based on this, a predetermined, stored emergency traffic pattern is selected from a li¬ brary of such patterns stored in ROM 66 or EROM 70 in step 81. The emergency traffic pattern places the system in the emergency signal control mode in step 82 which af- fords the emergency vehicle safe transit through the inter¬ section. After completing the transit, the emergency vehicle driver will normally execute a "Transit-Complete" message as in step 83, which will restore operation to the regular mode in step 84. He might, however, happen to neglect to issue that message and a timing function 86 that was started at the beginning of the request starts a timer in 87. If the "Transit-Complete" message is re¬ ceived, the timer 87 is reset in 95, but if not, the "Timer On 1 . 1 87 goes to the decision point 91. If the time-out period has elapsed, the "Yes" branch restores normal operation in 84, but if time-out has not elapsed, the "No" branch continues the timer. At the start of the execution of the emergency signal control mode in step 82, the received message is trans- mitted back to the emergency vehicle control in step 89. The vehicle control 47 compares the returned message with the original message in step 92 that tells the vehicle control 47 that the signal had received the message as transmitted and started the execution of the request. The comparison is done at the vehicle in step 93, which is a decision point. If the comparison affirms the message, the "Yes" branch from 93 goes to step 94, which produces a "Proceed" message in the vehicle that tells the driver that he may proceed safely. In case step 93 is negative indicating that the message returned was not the same as transmitted, the "No" branch from step 93 produces a "Repeat" message 97 at the vehicle which is displayed at the control console and tells the driver that something is amiss. He may then repeat the request or take different action at his discretion. The vehicle control 47 as shown in block diagram in Figure 5 contains a control logic unit 45 which provides the internal vehicle control logic functions that cor- ' respond to those performed by the control processor in the signal control 62, except it will have a different control program and will typically have less complexity. The basic operational steps of the control logic 45 were included in the flow chart of Figure 6. It follows that several additional functions may be included in the construction, such as self-tests, diagnostic tests and others which are conventional and are typically included in such systems and which are well known to those skilled in the art of designing control logic systems. In Figure 4, the display 41 and keyboard 42 are parts of the vehicle console 40 shown in Figure 4. The display 41 is capable of displaying messages such as "Proceed" or "Wait" or "Repeat" to the driver as appropriate or maintenance .and sytems status messages to inform the driver of the system status. The keyboard 42 is typically an alpha-numerical board as used on a conventional type¬ writer or it may be abbreviated to include only the keys required to send the special messages labeled thereon and the numeric keys. Such an abbreviated keyboard will have less capability, but may be less expensive and occupy less space in the vehicle cab. The control programs which are stored in the central processor's memory sections are organized in smaller sec¬ tions typically called modules. The major modules of the control program are shown in Figure 7. A main program 46 ties together and coordinates the operation of the indi¬ vidual modules. The Clock Calendar 47 produces time of day and the date. The Interpret Request module 48 re¬ ceives the request information in the format shown in Figure 3, organizes and validates it, if applicable, and transmits it to the Emergency Signal Patterns module 52 which produces a preselected signal pattern which it transmits to the Signal Controller module 49, which trans¬ mits the control commands to the Emergency Signal Control block 72 in Figure 5. A test routine module 51 continuously monitors the operation of the entire system and indicates any mal¬ functions it detects and decides, if applicable, what ac¬ tion to take, in order to correct the malfunction. In a second embodiment of the invention, also shown in Figure 1, the vehicle 1 does not communicate directly with the signal control 62 as described above but with a central control 3 which may be located at some central lo¬ cation from where it may serve a plurality of traffic signals. In the latter case, the vehicle radio equipment communicates via a two-way link 13,14 with two-way radio equipment 4,8 connected to an antenna 6 at the central location 3. A wire communication link 9 is then provided to connect the central control 3 with the signal control 62, instead of the radio link 16,17 used in the first embodiment. A system structured in this way has the advantages that the vehicle's normal two-way voice communications system is normally more powerful and farther reaching than a small dedicated separate two-way radio provided for sig¬ nal control only, and is normally provided in most emergency vehicles for general voice communications. Furthermore, the maintenance of a single central radio system is often more desirable and reliable than the maintenance of mul¬ tiple, distributed small units, and a wire link such as provided in this embodiment is very reliable and economi- cal and may readily be used also to transmit equipment alarms and malfunctions back to a central, attended loca¬ tion. It has the additional advantage that human interven¬ tion may be added to the centrally located system by the addition of an operator console 13 connected to the cen¬ trally located control 3 via a link 12 in an adjacent or another remote location 14. The human operator may be equipped to override the decisions made by the automatic equipment. He may also be able to control the signals in response to verbal requests from an emergency vehicle in which the automatic vehicle control is not functional or not installed. In the second embodiment different modes of operation may be provided relating to the interactions between the central control unit 3 and the signal control 62. In one of the preferred modes, the central control receives the character string and transmits the confirmation over the radio link (13,14) , as did the radio receiver and trans¬ mitter in the signal control 62 in the first preferred em- bodiment. In the second embodiment that information is then transmitted via the wire link 9, to and from the sig¬ nal control 62 which still has residing with it, as in the first embodiment, the function blocks pertaining to central processor, memories, signal controls, memories, modem and bus interface 75, as described under the first embodiment. In the case of the added human intervention with a con¬ sole 13, the human operator can receive verbally the request for transit through an intersection from an emergency ve¬ hicle and from his console,that may be similar to the vehicle console of Figure 4, activate the emergency signal control mode. It follows, that with the second embodiment, if human intervention is provided a fleet of emergency vehicles may contain vehicles that do not have a vehicle control 47 installed. In this way, an economical gradual transition can be made from a manual system to a system that is fully automatic. It follows that the present invention may be embodied, such that smaller groupings of street intersections that share a centrally located control may be created by a com¬ bination of the elements of the first and of the second embodiment. Such an arrangement may be advantageous in large complex intersections consisting of several interact¬ ing smaller junctions, as shown in diagrammatic form in Figure 2 , where there are two intersections, the main intersection with branches A,B,C,D,E and a smaller inter- section with branches F,G,H and I to the South. The main intersection has a main signal control 62-1 with an attached second control 62-2, both being served by a central con¬ trol 3-1 which contains the radio equipment. Two wire links 9-1 and 9-2 serve the two signal controls 62-1 and 62-2 respectively. OTHER EMBODIMENTS AND CAPABILITIES In the foregoing specification two preferred embodi¬ ments of the invention have been described. As explained, the preferred mode of operation employs an interactive method of two-way radio transmissions between a traffic light control and an emergency vehicle where all units, vehicular as well as stationary, transmit short bursts of digitally encoded radio messages, all on the same fre¬ quency. The communications protocol provides that any unit, before it transmits a message, insures that the fre¬ quency is available. If two units should transmit at the same time, or there is other interference, a check-sum embedded in the message informs the receiving unit that the message transmitted is incomplete and confirmation is not returned. If confirmation is not returned, the first transmitting unit, after a random delay, may repeat the message, and the probability is very small that a second attempt will fail, or that a third should fail and so forth, after repeated attempts. The traffic signal light control of intersections according to the invention affords a high degree of protec- tion against interference of the light control from simul¬ taneous operation of several emergency vehicles, in the same general area because the first vehicle seizing control of the light delivers to the signal control the unique iden¬ tity of that vehicle where it is stored in its electronic memory, for the duration of the execution of the vehicle's transit through the intersection. In the second embodi- ■ ent, employing central control of the signals, both the vehicle identity and the intersection identity is known to the control apparatus and nearly simultaneous requests can be separated by the control apparatus. The traffic signal control of the invention has the significant advantage that no special light signals are required which could confuse drivers of the general traf¬ fic or out-όf-towh drivers. in the second embodiment with human intervention it is possible to accommodate special traffic conditions that emerge in unusual situations which could not have been pre¬ dicted, such' as large fires, civil disturbances and catas- trophies and so forth. The signal light control, according to the invention, affords the capability of adding encryption of the encoding of the character strings used in the system for two-way communications. Such encryption eliminates or reduces the dangers from malicious interference with the system. En- crypting algorithms are now readily available, which provide a high degree of integrity of the transmissions. Encryption algorithms would in this case be added to the control pro¬ grams in both the vehicle control and the signal control. In Figure 7 an encryption algorithmmodule 55 ' is shown, under the main program. The signal light control system according to the inven¬ tion affords a simple means for adding rank or priority to different emergency vehicles by adding priority rank¬ ing to the vehicle identity code. Such a ranking table could be built into the control program at the signal con¬ trol. In Figure 7 a priority ranking module 50 is shown which inserts the vehicle identity code into the ranking table and allocates competing requests for transit in accordance with the priority ranking of the vehicle. The signal light control, according to the invention, affords a simple method of recording the time and vehicle identity of each vehicle transit through the intersection by the expedient of not erasing such information after transit is completed but by means of storing it in a memory module provided for the purpose, as shown at 60 in Figure 7. This memory module may then, later, be in- terrogated by the attachment of a paper printer or other display device. Such records may be of value in later evaluation of the efficiency of the control patterns stored in the emergency signal pattern module 52 or may be valuable • in the settling of the question of when transit took place. The memory module provided for storing past operations is shown as the Transaction Record 60 in Figure 7.

Claims: I CLAIM: 1. Traffic signal light control system for emer¬ gency vehicles comprising in combination: at least one traffic signal light; at least one emergency vehicle; emergency vehicle control apparatus means dis¬ posed with said emergency vehicle; traffic signal light control apparatus means disposed with said traffic signal light control; communications link means operatively connecting said emergency vehicle control apparatus means and said traffic signal light control- apparatus means; emergency vehicle control console means opera¬ tively communicating with said emergency vehicle control apparatus means; said signal control apparatus means comprising a central'processing unit with electronic memory means comprising an emergency sig¬ nal pattern module containing at least one emergency signal pattern, said emergency signal pattern module operatively respon¬ sive to command means from said emergency vehicle. 2. Traffic signal light control system as defined in claim 1 wherein said communications link means is a two-way link comprising: vehicle radio transmitter-receiver at the emer- gency vehicle, said vehicle radio trans¬ mitter-receiver operatively responsive to said vehicle control apparatus means; signal radio transmitter-receiver associated with and operatively responsive to said sig- nal light control apparatus means; said vehicle radio transmitter-receiver and said signal radio transmitter-receiver communicating on corresponding frequen¬ cies. 3. Traffic signal light control system as defined in claim 2 wherein said vehicle radio transmitter-receiver and said signal radio transmitter-receiver operate on the same frequency. 4. Traffic signal light control system as defined in claim 1 wherein said vehicle control console means comprises control keys and a display panel. 5. Traffic signal light control system as defined in claim 4 wherein said vehicle control console keys pro¬ duce alpha-numeric characters and wherein said display panel has alpha-numeric characters. 6. Traffic signal light control system as defined in claim 5 wherein said control keys produce preselected commands and alpha-numeric characters. 7. * Traffic signal light control system as defined in claim 1 wherein said vehicle control apparatus means further comprises: modulator-demodulator unit operatively communi- eating with said communications link means and with said vehicle control console means; data assembler for assembling said command means into a message character string. 8. Traffic signal light control system as defined in claim 7 wherein said message character string " comprises digitally encoded serially assembled alpha-numeric charac¬ ters. 9. Traffic signal light control system as defined in claim 8 wherein said digitally encoded message char¬ acter string further comprises a check-sum which communi¬ cates the quantity of binary digital characters in said character string. 10. Traffic signal light control system as defined in claim 7 wherein said vehicle control apparatus means further comprises control logic. 11. Traffic signal light control system as defined in claim 1 wherein said traffic signal light control ap¬ paratus means further comprises: modulator-demodulator operatively communicating with said communications link means; processor control system comprising central processing unit and said memory means; control bus with bus interface communicating with said processor control system and said modulator-demodulator. 12. Traffic signal light control system as defined in claim 11 wherein said memory means contains memory con¬ trol modules, said modules comprising: main program module linking together all modules; a clock calendar module producing time of day and date; signal controller module, operatively communi¬ cating with said signal control; emergency signal pattern module containing emer- gency signal patterns. 13. Traffic signal light control system as defined in claim.12 wherein said control modules further comprise a priority module. 14. Traffic signal light control system as defined in claim 12 further comprising encryption and transaction record modules. 15. Traffic signal light control system as defined in claim 1 wherein said command means comprise: first command from said vehicle control appara¬ tus means to said signal control apparatus -.means operating to request said signal con¬ trol apparatus means to execute said re¬ quest; second command from said signal control apparatus means to said vehicle control apparatus operating to confirm the execution of said first command. 16. Traffic signal light control system as defined in claim 5/ wherein said vehicle control console is oper¬ atively responsive to said second command to display on said display panel the character string of said second command. 17. Traffic signal light control system as defined in claim 15 wherein said first command comprises: vehicle departing route; vehicle arriving route; vehicle identity code; intersection identity code. 18. Traffic signal light control system as defined in claim 17 further comprising a check-sum. 19. Traffic signal light control system for emergency vehicles comprising in combination: communications link means between at least one emergency vehicle control apparatus means . and a plurality of traffic signal light control apparatus means, each operatively communicating with at least one traffic sig¬ nal light; vehicle control console means at the emergency vehicle, said vehicle control console means operatively communicating with vehicle control apparatus means and operatively responsive to said control console means and operatively communicating with said co - munications link means; signal control apparatus means associated with and operatively communicating with said traffic signal light and operatively re¬ sponsive to said communications link means; said signal control apparatus means each compris¬ ing a central processing unit with electronic memory means, said electronic memory means comprising an emergency signal pattern module, comprising at least one preselected emergency signal pattern, said emergency signal pattern module, in response to command means from said emer¬ gency vehicle, operating said traffic signal light in emergency signalling mode. 20. Traffic signal light control sytem as defined in claim 19, wherein said communications link means com¬ prise: vehicle radio transmitter-receiver at the emer- gency vehicle, said vehicle radio transmitter operatively responsive to said vehicle ap¬ paratus control means; a central control facility; signal radio transmitter-receiver means at said central control facility; a plurality of wire links, said plurality equal to said plurality of traffic signal light control apparatus; each wire link.operatively connecting said central control facility with each traffic signal light control means. 21. Traffic, signal light control system as defined in claim 20 further comprising a central control facility operat¬ or console, said operator console capable of providing human intervention in the emergency control of said traffic lights.

Inventors: OBECK CARL J, OBECK, CARL, J.
Applicants: BOURSE TRADING LTD, BOURSE TRADING COMPANY, LTD.
Application year: 1985
Main classification: G08C19
IPC codes: G08G1