Coordinated two-dimensional progression traffic signal system

• US 5,821,878 A
• Filed: 11/16/1995
• Issued: 10/13/1998
• Est. Priority Date: 11/16/1995
• Status: Expired due to Fees

• Current Assignee: Subhash C. Raswant
• Original Assignee: Subhash C. Raswant
• Inventors: Raswant, Subhash C.
• Primary Examiner(s): Hofsass, Jeffery
• Assistant Examiner(s): Pope, Daryl C.
• Application Number:
  US08/559,008
• Time in Patent Office: 1,062 Days
• Field of Search: 340/910, 340/911, 340/913, 340/919, 340/924, 340/932, 364/436
• US Class Current: 340/907
• CPC Class Codes: G08G 1/081 Plural intersections under common control
• CPC Class Codes: G08G 1/082 Controlling the time between beginning of the same phase of a cycle at adjacent intersections

Abstract

A method of controlling traffic signals on existing grid-like systems of avenues and crossing streets. Two phase traffic signals, red and green, wherein both phases are equal in duration and the amber interval is a part of the green interval. The coordinated two-dimensional progression traffic signal system requires simultaneous changes of the signal cycle at three levels of the designated grid plan. The duration of each phase of the signal cycle is determined by the time required to traverse two contiguous lengths of the optimum grid rectangle. A band length is determinable from the calculation of the duration of the phases and corresponds to the integral number of roadway intersections to be crossed by a vehicle. Between bands, adjacent band widths are in the reciprocal phase from one another. Between avenues, parallel band widths on adjacent avenues and streets are also in reciprocal phases from one another, and between interphases. Interfacing band ends are also in a reciprocal phasing sequence relation to one another, so as to produce a checkerboard pattern of alternating red and green phases of the traffic signals, shown in band interfaces mesh into one another in a saw tooth pattern.

Claims

1. A method of controlling vehicular and pedestrian traffic flow and traffic light controls on a road traffic network of a type having a plurality of grid-like intersections between a first set of road portions running substantially parallel to one another and a second set of road portions also running substantially parallel to one another, wherein said first set of road portions and said second set of road portions are substantially perpendicular to one another, wherein traffic can cross intersections, and wherein first set of road portions is further segmented into a plurality of bands of equal lengths, said method comprising the steps of:

providing at each of said intersections, a vehicle traffic signal having two major phases, "go" and "stop" of predeterminable equal time durations;

determining said time duration, based on predetermined expected travel speeds of traffic on said road portions, wherein said time duration of the phase interval corresponds to said grid and a factor selected based on the time required to turn a corner in said grid;

simultaneously changing the phase of all of said signals at their respective intersections results in signals at adjacent first road portions within said band to be in opposite and reciprocal phase with respect to one another; and

wherein simultaneously changing the phase of all of said signals with adjacent bands are opposite and reciprocal relative to one.

2. The method of controlling vehicular and pedestrian traffic flow of claim 1 further comprising the step of:

offsetting said bands from one another by a predetermined length selected to correspond to an inter-street distance in a saw-tooth pattern.

14. The method of controlling vehicular and pedestrian traffic flow of claim 1 further comprising the step of separating vehicular and pedestrian traffic on two way streets by the use of a four phase signal cycle, wherein two turning phases accommodates left and right turns simultaneously and two phases permit through traffic (without permitted turns) to accommodate parallel uninterrupted pedestrian movement on the sidewalks.

3. The method of controlling vehicular and pedestrian traffic flow as claimed in claimed 2, wherein said time duration is about 42 seconds on weekdays.

4. The method of controlling vehicular and pedestrian traffic flow as claimed in claimed 2, wherein said time duration is about 33 seconds on weekends.

5. The method of controlling vehicular and pedestrian traffic flow as claimed in claimed 2 wherein the speed during weekdays of said vehicles on said first and second sets of road portions is about 20 and 18 miles per hour, respectively.

6. The method of controlling vehicular and pedestrian traffic flow as claimed in claimed 2 wherein the speed during weekends of said vehicles on said first and second sets of road portions is about 25 and 22 miles per hour, respectively.

7. The method of controlling vehicular and pedestrian traffic flow as claimed in claimed 1 such that a band width is defined as the whole number of intersections expected to be passed by a vehicle travelling on a road portion of said first set of road portions during the "go" phase of said traffic signal.

8. The method of controlling vehicular and pedestrian traffic flow as claimed in claimed 1 wherein said first set of road portions are wider than said second set of road portions.

9. The method of controlling vehicular and pedestrian traffic flow as claimed in claimed 1 wherein said first set of road portions are avenues and said second set of road portions are cross streets.

10. The method of controlling vehicular and pedestrian traffic flow as claimed in claimed 1 wherein:

space="preserve" listing-type="equation">P=t.sub.b +t.sub.a +f.sub.t (when t.sub.b >

t.sub.a) in seconds

space="preserve" listing-type="equation">P=2t.sub.b +f.sub.t (when t.sub.b =t.sub.a) in seconds

Where

P=phase duration in seconds

t_b =travel time between avenues in seconds

t_A =travel time between streets in seconds

f_t =optimum factor for one turn in seconds

12. The method of controlling vehicular and pedestrian traffic flow of claim 10 further comprising the step of applying the algorithm of claim 10 to computer software to adjust signal timing on a grid network during discrete time periods as a function of changes in travel speeds as these changes in travel speeds relate to changes in traffic composition and congestion.

11. The method of controlling vehicular and pedestrian traffic flow as claimed in claimed 1 wherein:

space="preserve" listing-type="equation">N=(P-D.sub.2)/t.sub.a

Where

D₂ =delay in seconds for traffic turning left.

13. The method of controlling vehicular and pedestrian traffic flow of claim 11 further comprising the step of applying the algorithm of claim 11 to computer software to adjust signal timing on a grid network during discrete time periods as a function of changes in travel speeds as these changes in travel speeds relate to changes in traffic composition and congestion.