Method and apparatus for controlling traffic flow in accordance with traffic presence

Claim 2

In a traffic control system for controlling the operation of traffic signal means displaying at least go and caution signals to each of at least first and second intersecting traffic phases, the improvement comprising: first and second presence detector means for respectively monitoring an area in the path of said first phase and an area in the path of said second phase to the intersection of said phases and providing first and second presence signals so long as traffic is present in said respective areas, signal control means for controlling said signal means to display a go signal to said first phase so long as said first presence signal is provided and said second presence signal is not provided, said signal control means including circuit means for timing an extended go interval for said go signal display to said first phase upon the occurrence of said second presence signal being provided during a period in which said first presence signal is provided, caution signal control means for, upon termination of said extended go interval, controlling said signal means to display a caution signal to said first phase, said caution signal control means including caution timing means for timing a predetermined caution time interval for said caution signal display, all red clearance control means for, upon termination of said caution time interval, controlling the said signal means to display a stop signal for each of said phases, said all red clearance control means including circuit means adapted to be coupled to presence detector means located at the intersection of said phases and which provides an all red presence signal so long as traffic is present in a predetermined area of sAid intersection, said circuit means controlling said signal means to display stop signals to each of said phases so long as said all red presence signal is developed.

Claim 3

In a traffic control system for controlling the operation of traffic signal means displaying traffic commands to at least first and second intersecting traffic phases wherein the traffic commands displayed to each phase sequentially include at least one go interval and a caution interval the improvement comprising: traffic interval sequencer means for receiving trigger signals and upon receipt of each said trigger signal allocating a different one of said intervals to one of said phases; first and second presence detector means for respectively monitoring an area in the path of said first phase and an area in the path of second phase to the intersection of said phases and providing first and second presence signals so long as traffic is present in the respective areas; sequencer control means for applying said trigger signals to said sequencer means, and including go signal control means for receiving said first and second presence signals to control said sequencer means to allocate a go signal interval to said first phase so long as said first presence signal is provided and said second presence signal is not provided, said go signal control means including circuit means for timing an extended go interval in response to said second presence signal being provided during the period that said first presence signal is provided and then providing a said trigger signal for application to said sequencer means to allocate a said caution interval to said first phase; caution signal control means for controlling the time duration of said caution interval for said first phase including circuit means adapted to be coupled to presence detector means which provides a caution presence signal so long as traffic is present in a predetermined area of said intersection, said circuit means applying a said trigger signal to said sequencer means to terminate said caution interval for said first phase upon the absence of said caution presence signal.

Claim 4

In a traffic control system for controlling the operation of traffic signal means displaying traffic commands to at least first and second intersecting traffic phases wherein the traffic commands displayed to each phase sequentially include at least one go interval and a caution interval the improvement comprising: traffic interval sequencer means for receiving trigger signals and upon receipt of each said trigger signal allocating a different one of said intervals to one of said phases; first and second presence detector means for respectively monitoring an area in the path of said first phase and an area in the path of second phase to the intersection of said phases and providing first and second presence signals so long as traffic is present in the respective areas; sequencer control means for applying said trigger signals to said sequencer means, and including go signal control means for receiving said first and second presence signals to control said sequencer means to allocate a go signal interval to said first phase so long as said first presence signal is provided and said second presence signal is not provided, said go signal control means including circuit means for timing an extended go interval in response to said second presence signal being provided during the period that said first presence signal is provided and then providing a said trigger signal for application to said sequencer means to allocate a said caution interval to said first phase; caution signal control means for controlling the time duration of said caution interval for said first phase including circuit means adapted to be coupled to presence detector means which provides a caution presence signal so long as traffic is present in a predetermined area of said intersection, said circuit means applying a said trigger signal to said sequencer means to terminate said caution interval for said first phase upon the absence of said caution presence signal.