Abstract:
A system and method for moving vehicular traffic in a single lane through a control zone requires creation of a control protocol. The protocol establishes a spacing distance “s” and a speed “v” for each vehicle in the control zone. A computer then controls movement of a visible signal through the control zone in accordance with the established protocol. Electronic regulators monitor the distance “s” between the signal and the vehicle, and the system alarms when “s” becomes greater than a predetermined distance “d”.

Description:
FIELD OF THE INVENTION 
     The present invention pertains generally to systems and methods for controlling vehicular traffic in congested areas. More particularly, the present invention pertains to systems and methods that provide visual signals for use in maintaining a substantially constant speed and a substantially constant spacing for vehicles as they traverse a control zone. The present invention is particularly, but not exclusively, useful as a system and method for the control of vehicular traffic through roadway anomalies such as bridges, tunnels and construction sites. 
     BACKGROUND OF THE INVENTION 
     Traffic control in congested areas is a major concern for all involved. Not surprisingly, traffic congestion is all too often exacerbated by the traffic itself. Either drivers become impatient and indulge in lane changes, or they are simply overwhelmed by situational variations that cause them to engage in erratic speed changes. Both responses (i.e. lane changes and speed changes) are very detrimental to smooth traffic flow. In almost every case, the consequence is a drastic diminution in traffic throughput from a theoretical maximum to an actual throughput that is around fifty to seventy percent of the theoretical maximum. 
     By way of example, a single lane of traffic in a congested area, with a posted speed limit of 60 mph and a constant spacing between vehicles of six car lengths, can theoretically accommodate 3,232 vehicles per lane, per hour. Due to the traffic friction caused by lane changes and speed variations, however, the actual traffic throughput under these conditions will more realistically be in a range between about 1,900 and 2,200 vehicles per lane per hour. Fortunately, congested areas can be easily identified and will typically be found in tunnels, on bridges, and through construction sites. Moreover, they are typically only a few miles long, at most. Nevertheless, they pose the real possibility of creating traffic “bottlenecks” that can be very disruptive. 
     In light of the above, it is an object of the present invention to provide a system and a method for moving vehicular traffic through an area of potential congestion that effectively maintains a steady flow of traffic. Another object of the present invention is to provide for a steady traffic flow in a control zone by establishing a spacing distance and a speed for each vehicle as it passes through the control zone. Yet another object of the present invention is to provide a system and method for controlling vehicular traffic that is easy to implement, is simple to use, and is comparatively cost effective. 
     SUMMARY OF THE INVENTION 
     A system and method for controlling vehicular traffic in accordance with the present invention requires the establishment of a control protocol. Specifically, a control protocol is established for each individual vehicle that will be entering a control zone. In accordance with the present invention, this protocol involves determining a safe stopping distance “sd” for each vehicle, and establishing a speed “v” at which the vehicle is required to proceed through the control zone. For the present invention, implementation of the control protocol is accomplished by moving a signal through the control zone at the speed “v”, establishing a distance “d” between consecutive signals, and monitoring the spacing distance “s” at which each vehicle follows its dedicated signal. As envisioned for the present invention, the distance “d” between consecutive signals is determined by three considerations. These are: 1) a guesstimate of the distance a vehicle will follow its dedicated signal; 2) the length of the vehicle; and 3) the safe stopping distance of the next-in-line vehicle. 
     Structurally, the system of the present invention includes a sensor that is located on the roadway ahead of the control zone. Preferably, this sensor will be a series of inductive coils or pneumatic tubes that are laid down on the roadway, or embedded in the roadway. The purpose of the sensor is to determine whether a vehicle is approaching the threshold of the control zone and, if so, its overall length “l”. Further, based on its length “l”, a safe stopping distance “sd” can be estimated for the vehicle. Additionally, the system includes a plurality of regulators that are strategically positioned along the roadway in the control zone. The purpose of these regulators is to monitor the movement of each individual vehicle and, in particular, the spacing distance “s” at which each vehicle respectively follows its dedicated signal. 
     An essential structural component of the system is a conveyor and its associated signal. In detail, the conveyor will be a mechanism that is positioned along the lane of traffic in the control zone for moving a visible signal through the control zone at the speed “v”. As envisioned for the present invention, the combination of conveyor and signal can have any of several embodiments. For one, the conveyor can be a row of laser light emitters. In this case the signal will be a beam of laser light. For another, the conveyor can be a row of incandescent or fluorescent lights. In this case the signal will be a moving point of light. For yet another embodiment, the conveyor can be a moving track or belt and the signal can be a pop-up flag that will move on the track or belt through the control zone. Importantly, a separate signal is provided for each control protocol. And, the signals for a contiguous sequence of control protocols can each have a unique identifier (e.g. a different color). Further, as envisioned for the present invention, the conveyor can be positioned on the roadway, beside the roadway, or on support structures over the roadway. 
     Functionally, the system of the present invention employs a computer for coordinating the various operations of the system&#39;s other components. Specifically, as a vehicle approaches the threshold of the control zone, the computer is alerted by the sensor to create a control protocol for the vehicle. Based on the vehicle&#39;s length “l”, as determined by the sensor, a safe stopping distance “sd” is established by the computer for the vehicle. Also, the distance between signals “d” is established by the computer. Next, when the vehicle arrives at the control zone threshold, the computer activates a signal on the conveyor. This signal is then moved by the conveyor through the control zone at the speed “v”, and the vehicle follows the signal. 
     During the movement of a vehicle through the control zone, the regulators that are positioned along the roadway monitor the vehicle&#39;s progress. More specifically, they are used to monitor the distance “s” between the vehicle and its dedicated signal. In the unlikely event a vehicle either overruns its dedicated signal, or drops behind its dedicated signal by more than a calculable distance, the computer will create an alarm. Initially, actions will be taken to encourage the vehicle driver to restore the vehicle to its correct distance “s”. If the driver does not do so, then the computer will adjust the speed “v” for upstream and downstream vehicles to maintain maximum flow. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The novel features of this invention, as well as the invention itself, both as to its structure and its operation, will be best understood from the accompanying drawings, taken in conjunction with the accompanying description, in which similar reference characters refer to similar parts, and in which: 
         FIG. 1  is a schematic of a roadway for vehicular traffic identifying various zones used by the present invention for the control of traffic; 
         FIG. 2A  is a perspective view of a column of traffic traveling along a single lane of the roadway through a control zone; 
         FIG. 2B  is an elevation view of two vehicles traveling in the control zone; 
         FIG. 3  is a schematic showing the inter-relationships of components for the present invention; 
         FIG. 4A  is a drawing of a control protocol of the present invention employing laser beam signals positioned along the roadway in the control zone; 
         FIG. 4B  is a drawing of a control protocol of the present invention employing light point signals positioned along the roadway in the control zone; 
         FIG. 4C  is a drawing of a control protocol of the present invention employing pop-up flag signals positioned along the roadway in the control zone; 
         FIG. 4D  is a drawing of a control protocol of the present invention employing color strip signals painted on the roadway in the control zone; and 
         FIG. 5  is a logic flow chart showing the methodology steps employed by the present invention. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring initially to  FIG. 1  a roadway is shown organized for purposes of the present invention and is designated  10 . As shown, a lane of traffic for the roadway  10  includes three different zones that are individually identified according to their function. First, there is an information zone  12  wherein drivers are informed of upcoming traffic control requirements. This information can be provided with signs and other traffic control devices (not shown). For drivers who do not wish to proceed, an exit is provided before they enter the approach zone  14 . Upon entering the approach zone  14 , the driver becomes committed to progressing through the downstream control zone  16 . As indicated, the transition from approach zone  14  to control zone  16  is delineated by a threshold  18 . In the approach zone  14 , speed requirements are posted, and a sensor  20  is used to determine the length and speed of each vehicle. As envisioned for the present invention, the sensor  20  can be a series of inductive loops or pneumatic tubes that are positioned either on the roadway  10 , or embedded in the roadway  10 . In any event, by the time a vehicle  22  passes the threshold  18 , its general overall length “l” has been determined by the sensor  20 . The vehicles  22   a ,  22   b , and  22   c  shown in  FIG. 2A  are only exemplary of various type vehicles that may be controlled by the present invention. 
     In  FIG. 2A  a plurality of vehicles  22  are shown traveling in the control zone  16 . Specifically, it will be seen that each vehicle  22  is following a respectively dedicated signal  24 . For example, the vehicle  22   a  is shown following a signal  24   a , while the vehicles  22   b  and  22   c  are shown following respectively dedicated signals  24   b  and  24   c . In further detail, the signal  24  is moved through the control zone  16  by a conveyor that is positioned along the lane of traffic and is used as a mechanism for moving signals. The conveyor (mechanism) can be positioned either on the roadway  10 , or beside the roadway  10 . As envisioned for the present invention, the signal  24  can be any one of several different type signals. Examples of various type signals that are suitable for the present invention are disclosed in greater detail below. The illustration of the signals  24   a ,  24   b  et seq. as being pop-up flags in  FIGS. 2A and 2B  is only for exemplary purposes. Other embodiments of the types of signals that can be utilized are shown in  FIGS. 4A-4D . 
     Still referring to  FIG. 2A , it will be seen that in addition to following its own dedicated signal  24 , each vehicle  22  travels within a distance “d” that is measured between consecutive signals  24 . Importantly, the determination of the distance “d” for a vehicle  22  takes into account the safe stopping distance “sd” of the immediately following vehicle. For purposes of this disclosure, a subscript “1” is used with reference to a leading vehicle, and a subscript “2” is used with reference to its next-in-line, immediately following vehicle (et seq.). With this in mind, consider the two vehicles  22   a  and  22   b  shown in  FIG. 2B . 
     In  FIG. 2B , the length “l 1 ” of vehicle  22   b  is determined as it passes over the sensor  20  prior to arriving at the threshold  18 . This length “l 1 ” is then used to calculate a safe stopping distance “sd 1 ” for the vehicle  22   b . Using a guesstimate for “s” a distance “s g1 ” is established for the vehicle  22   b . The distance “d 1 ” will then be the sum of “s g1 ”, “l 1 ” and “sd 2 ” (d 1 ≧s g1 +l 1 +sd 2 ). Stated differently, the distance d 1  will be used as a minimum distance between the signal  24   b  that the vehicle  22   b  follows and the next consecutive signal  24   a . Similarly, the minimum distance “d 2 ” for vehicle  22   a  will be the sum of “s g2 ”, “l 2 ” and “sd 3 ” (d 2 ≧s g2 +l 2 +sd 3 ). 
     In addition to establishing the distance “d” between consecutive signals  24  (e.g. the distance between signal  24   a  and signal  24   b ), the control protocol for the present invention needs to be continuously evaluated as the vehicle  22  proceeds through the control zone  16 . More specifically, as noted above, the actual distance “s 1,2 ” at which a vehicle  22  follows its dedicated signal  24  is monitored by the regulators  26   a,b . When the vehicle  22  either overtakes a signal  24 , or it falls behind so there is an unsafe distance between the vehicle  22  and the signal  24  behind the vehicle  22 , an alarm should sound. Mathematically these conditions can be respectively expressed for a lead vehicle as: s 1 =0 [overtaking]; and d 1 −l 1 −s 1 &lt;sd 2  [falling behind]. 
     As mentioned above, compliance with the control protocol is monitored along the length of the control zone  16  by a series of regulators  26 . The regulators  26   a  and  26   b  shown in  FIG. 2A  are exemplary. As envisioned for the present invention, the regulators  26  may be any device well known in the pertinent art that can monitor the distance “s” for each vehicle  22 , such as a video camera. Further, these regulators  26  can be conveniently positioned along the control zone  16 , as required. 
       FIG. 3  indicates that the present invention, with its control protocols, can be centrally managed by a computer  28 . As shown in  FIG. 3 , for this interaction each vehicle  22  provides input to the computer  28  via the roadbed sensor  20  and the regulators  26 . On the other hand, the computer  28  provides input to the vehicle  22  via the signal  24  (i.e. in accordance with a control protocol). 
     To initiate a control protocol, the line  30  in  FIG. 3  indicates that with input from the sensor  20  (i.e. vehicle length “l”), the computer  28  is able to establish a value for the safe stopping distance “sd” of the vehicle  22 . Recall, this is done for each vehicle  22 . Using “l” of the lead vehicle (i.e. l 1 ) and the safe stopping distance of the following vehicles (i.e. sd 2 ), in addition to a guesstimate value for “s” (i.e. “s g1 ”) a distance between signals “d 1 ” is calculated for the lead vehicle. Then, as the vehicle  22  traverses the control zone  16 , the regulators  26  monitor the actual value for “s”. When either s 1 =0, or the expression d 1 −s 1 −l 1 &lt;sd 2  is satisfied, the line  32  in  FIG. 3  indicates the computer  28  can use this information to activate an alarm for the computer operator (i.e. computer  28 ). The computer  28  will then appropriately adjust any or all control protocols, as required. 
     As mentioned above, several types of signals  24  can be used for purposes of the present invention. Further, although the present invention is intended to separately control single lanes of traffic, the present invention is adaptable to a multi-lane roadway  10 . As shown in  FIGS. 4A-D  the roadway  10  may have side-by-side lanes, such the lanes  34   a  and  34   b . In this event, a different signal  24  may be used simultaneously by different vehicles  22  in the respective lanes  34   a  and  34   b . Consequently, the control protocols for the vehicles  22  that are using different signals  24  will also be different. 
     Examples of the various type signals  24  that can be employed for the present invention are shown in  FIGS. 4A-D  with each of these figures generally designated as conveyor  11   a - d . These include: a laser beam  36   a - d  ( FIG. 4A ); a point of light  38   a - d  ( FIG. 4B ); or a pop-up flag  40   a - d  ( FIG. 4C ). The a-d designations more clearly depict how the signal moves through the control zone with the signal designated “a” appearing first and the signal designated “d” appearing last. Only one signal is present at a time as the vehicle follows the moving signal through the control zone. In each case, the signal  24  is moved through the control zone  16  at a speed “v” according to the established control protocol. Further, consecutive signals  24  can each have a unique identifying feature, such as different colors. As an alternative or augmentation to the moving signals  24  ( FIGS. 4A-C ),  FIG. 4D  shows that a series of colored strips  42  can be painted on the roadway  10 . If such strips are used, the vehicles  22  can be informed in the information zone  12  that at least one, but no more than two colored strips should be visible from behind the vehicle  22  that is being followed. 
     Implementation of the control protocols of the present invention will be best appreciated by reference to  FIG. 5 . In  FIG. 5 , the action block  44  and inquiry block  46  together indicate that a control protocol is initiated when a vehicle  22  is present in the approach zone  14 . When a vehicle  22  is present in the approach zone  14 , the computer  28  will perform the functions indicated by blocks  48 ,  50  and  52 . Specifically, block  48  indicates that after a vehicle has been detected, but prior to entering the control zone  16 , the length “l” of the vehicle is determined. This length “l” is then used to establish a safe stopping distance “sd” for the vehicle, and it is used to generate a guesstimate “s g ” of the distance the vehicle will follow its dedicated signal  24 . Block  50  then indicates that a distance “d” is established for the lead vehicle (i.e. the vehicle immediately preceding the vehicle that is entering the control zone  16 ). More specifically, this distance will be established by the expression “d 1 =l 1 +s g1 +sd 2 ”, wherein “sd 2 ” is the safe stopping distance of the next following vehicle (i.e. the vehicle that is entering the control zone). 
     During transit of a vehicle  22  through the control zone  16 , the regulators  26  monitor the spacing distance “s”. Specifically, the computer  28  continuously determines whether any vehicle  22  has overtaken the signal  24  it is following (i.e. s=0) or whether the vehicle  22  has fallen behind (i.e. d 1 −l 1 −s 1 &lt;sd 2 ) (inquiry block  54 ). If neither of these has happened in the control zone  16 , the inquiry block  56  indicates that the control protocol has ended, and the vehicle  22  exits the control zone  16 . On the other hand, if either s=0, or d 1 −l 1 −s 1 &lt;sd 2 , block  58  indicates that an adjustment may be required for both upstream and downstream signals  24  (i.e. the control protocols for vehicles  22  that are in front of and behind the errant vehicle  22  are re-evaluated). In most instances, this can be accomplished merely by changing the required “v” at which the conveyor (mechanism) is moving the signals  24  through the lane for the affected control protocols. Importantly, the computer  28  needs to be capable of simultaneously managing a plurality of control protocols. 
     While the particular Traffic Control System as herein shown and disclosed in detail is fully capable of obtaining the objects and providing the advantages herein before stated, it is to be understood that it is merely illustrative of the presently preferred embodiments of the invention and that no limitations are intended to the details of construction or design herein shown other than as described in the appended claims.