Abstract:
The present invention is a traffic-weaving-free grade-separated road junction that provides for continuous flow of traffic and provides exterior exits and entrances only (i.e., it provides right-side exits and entrances only where the convention is for traffic to keep to the right, but provides left-side exits and entrances only where the convention is for traffic to keep to the left). Two of the embodiments have two loop ramps and require as few as two bridges. Two other embodiments have no loop ramps and require as few as three bridges. In addition, four other embodiments have one loop ramp and require as few as three bridges; two other embodiments have no loop ramps and require as few as four bridges; and two embodiments provide U-turn ramps, have no loop ramps, and require as few as three bridges. Compared to prior art junctions that also provide for continuous flow of traffic, avoid weaving, and provide exterior exits and entrances only, the present invention can be constructed with fewer bridges and/or fewer loop ramps. Therefore, the present invention provides reduced structure-related costs and/or increased safety and speed for drivers. In addition, because it can be constructed with fewer bridges than said prior art junctions, the present invention provides lower aesthetic impacts and other environmental costs. Finally, the embodiments of the present invention provide an additional set of design options for road engineers to choose from when designing within particular constraints of right-of-way, topography, and other factors.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority of U.S. Provisional Application No. 61/413432, filed 13 Nov. 2010, which is hereby incorporated by reference in its entirety. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    This invention relates to grade-separated junctions for intersecting roads, and more particularly, to grade-separated junctions that provide for the continuous and weaving-free flow of traffic on intersecting roads, and that provide exterior exits and entrances only. For the purposes of this patent, the term ‘exterior exit’ refers to a right-side exit where the convention is for traffic to keep to the right, but refers to a left-side exit where the convention is for traffic to keep to the left, while the term ‘exterior entrance’ refers to a right-side entrance where the convention is for traffic to keep to the right, but refers to a left-side entrance where the convention is for traffic to keep to the left. 
         [0003]    Grade-separated junctions are more commonly known as interchanges. There are many interchange configurations that permit free flow of traffic for traffic traveling directly through the interchange or turning left or right onto the intersecting road or roads. However, these existing configurations have disadvantages in one or more of the following aspects: safety, traffic capacity, construction costs, maintenance costs, modification costs, right-of-way costs, or environmental costs. 
         [0004]    The ‘cloverleaf’ configuration (U.S. Pat. No. 1,173,505), because it requires as few as one bridge, has relatively low structure-related costs, but as is well-known, the weaving of traffic exiting from and entering onto the mainlines reduces the safety and capacity of the interchange. A common treatment of interchanges is the addition of separate collector-distributor roads. This removes weaving-related problems from the mainlines, but weaving still exists on the collector-distributor roads. In addition, the addition of collector-distributor roads increases structure-related costs and right-of-way requirements. Another disadvantage of the cloverleaf configuration is that the loop ramps of the cloverleaf result in large right-of-way requirements and/or low design speeds. 
         [0005]    Several weaving-free interchange configurations have since been developed. The lour-level directional&#39; or ‘stack’ configuration (see Exhibit 10-33 B and C from A Policy on the Geometric Design of Highways and Streets, Fourth Edition, by the American Association of State Highway and Transportation Officials) provides improved capacity and safety, but has high structure-related costs due to the length and height of structures required. In addition, because of the height of some of the structures, there can be problems with icing in cold conditions. Another problem is that the height of the structures can be problematic from an urban design and aesthetic perspective. Finally, future modifications of the configuration are expensive. 
         [0006]    The semi-directional (see Exhibit 10-33 A of A Policy on the Geometric Design of Highways and Streets, Fourth Edition, by the American Association of State Highway and Transportation Officials) or ‘turbine’ configuration can have somewhat lower structure-related costs than the four-level directional. An uncommon modification of the ‘turbine’ (see Fig. VB6.11 from VicRoads Supplement to the Austroads Guide to Road Design Part 4C—Interchanges, Rev. 1.1), sometimes called the ‘windmill’, can have still lower structure-related costs, as it can be constructed using as few as five bridges. 
         [0007]    Two lower-cost weaving-free modifications of the cloverleaf configuration also exist, each with two loop ramps. One, a ‘semidirect’ interchange (see Exhibit 10-33 of A Policy on the Geometric Design of Highways and Streets, Fourth Edition, by the American Association of State Highway and Transportation Officials), sometimes called a ‘clover-stack’, still has relatively high structure-related costs due to the height and length of two of the structures required. Another type of semidirect interchange (see FIG. 10 of “A model for calculating optimal vertical alignments of interchanges” by Lee and Cheng, Transportation Research Part B, Vol. 5, Issue 5, pp. 423-445), sometimes called a ‘clover-turbine’, can have somewhat lower structure-related costs. 
         [0008]    Nevertheless, the ‘turbine’, ‘windmill’, ‘clover-stack’, and ‘clover-turbine’ configurations are inappropriate for many applications because of excessively high structure-related costs. 
         [0009]    Five other prior weaving-free modifications of the cloverleaf configuration exist. A rare such configuration, which has four loop ramps and requires as few as five bridges, is sometimes called a ‘braided’ cloverleaf. A built example of this configuration exists near Frankfurt, Germany, at the junction of the bundesautobahnen 3 and 5. Another configuration is shown in FIGS. 3h and 3i of International Patent Application Publication No. WO 2004/104301. This configuration has four loop ramps, requires as few as five bridges, and requires a very large right-of-way. The remaining three prior weaving-free modifications of the cloverleaf configuration each have two loop ramps and require as few as three bridges. The first is the ‘continuous flow cloverleaf-type interchange’, described in U.S. Pat. No. 4,861,184. The second is sometimes called the ‘partially-unrolled cloverleaf’. A built example of this configuration exists near Reading, UK, at the junction of the M4 and A329 motorways. The third, more common configuration is sometimes called the ‘clovermill’, because it uses two left-turn ramps with a form similar to those of the ‘windmill’. A built example of this configuration exists at the junction of Interstate 395 and King St. in Alexandria, Va., USA. 
         [0010]    There are numerous existing interchange configurations where some or all of the exits or entrances are interior rather than exterior (i.e., where some exits or entrances are located at the left side of the road where the convention is for traffic to keep to the right, or where some exits or entrances are located at the right side of the road where the convention is for traffic to keep to the left). Some examples are found in French Pat. No. 2,442,915, and U.S. Pat. No. 1,689,161, U.S. Pat. No. 2,941,454, U.S. Pat. No. 3,107,590, U.S. Pat. No. 7,425,104, and some embodiments of U.S. Pat. No. 4,630,961. These configurations are generally deprecated for system interchange applications because interior exits, as defined here, have been recognized as causing safety and operational problems. 
         [0011]    All prior existing weaving-free interchange configurations that provide for continuous flow of traffic and that provide exterior exits and entrances only require three or more bridges. All prior existing weaving-free interchange configurations that provide for continuous flow of traffic, have no loop ramps, and provide exterior exits and entrances only require five or more bridges. Because reducing the number of structures in an interchange tends to reduce structure-related costs—that is, construction, maintenance, and modification costs—as well as aesthetic impacts and other environmental costs, there is a need for a weaving-free interchange configuration that provides for continuous flow of traffic, provides exterior exits and entrances only, and can be constructed with fewer than three bridges. In addition, because loop ramps provide lower capacity and safety for a given amount of right-of-way, there is also a need for a weaving-free interchange configuration that provides for continuous flow of traffic, has no loop ramps, provides exterior exits and entrances only, and can be constructed with fewer than five bridges. Finally, because prior interchange configurations may not be appropriate for some sites with particular constraints of right-of-way, topography, and other factors, there is a general need for new interchange configurations to provide more design options to transportation planners and engineers. 
       BRIEF SUMMARY OF THE INVENTION 
       [0012]    The present invention is a traffic-weaving-free grade-separated road junction that provides for continuous flow of traffic and provides exterior exits and entrances only. Two of the embodiments have two loop ramps and require as few as two bridges. Two other embodiments have no loop ramps and require as few as three bridges. In addition, four other embodiments have one loop ramp and require as few as three bridges; two other embodiments have no loop ramps and require as few as four bridges; and two embodiments provide U-turn ramps, have no loop ramps, and require as few as three bridges. Compared to prior art junctions that also provide for continuous flow of traffic, avoid weaving, and provide exterior exits and entrances only, the present invention can be constructed with fewer bridges and/or fewer loop ramps. Therefore, the present invention provides reduced structure-related costs and/or increased safety and speed for drivers. In addition, because it can be constructed with fewer bridges than said prior art junctions, the present invention provides lower aesthetic impacts and other environmental costs. Finally, the embodiments of the present invention provide an additional set of design options for road engineers to choose from when designing within particular constraints of right-of-way, topography, and other factors. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF DRAWINGS 
         [0013]      FIGS. 1 through 30  are plan view schematics of the various embodiments of the invention. Note that the drawings of  FIGS. 2 ,  4 ,  6 ,  8 ,  10 ,  12 ,  14 ,  16 ,  18 ,  20 ,  22 ,  24 ,  26 ,  28 , and  30  are based on horizontal reflections of the drawings of  FIGS. 1 ,  3 ,  5 ,  7 ,  9 ,  11 ,  13 ,  15 ,  17 ,  19 ,  21 ,  23 ,  25 ,  27 , and  29 , respectively. 
           [0014]      FIG. 1  shows the arrangement of road surfaces in a first embodiment, which has two loop ramps and requires as few as two bridges; 
           [0015]      FIG. 2  shows a second embodiment, which has two loop ramps and requires as few as two bridges. 
           [0016]      FIG. 3  shows the arrangement of road surfaces in a third embodiment, which has no loop ramps and requires as few as three bridges; 
           [0017]      FIG. 4  shows a fourth embodiment, which has no loop ramps and requires as few as three bridges. 
           [0018]      FIG. 5  shows the arrangement of road surfaces in a fifth embodiment, which has no loop ramps and requires as few as three bridges. U-turn ramps are also provided for each leg of the interchange; 
           [0019]      FIG. 6  shows a sixth embodiment of the invention, which has no loop ramps and requires as few as two bridges. U-turn ramps are also provided for each leg of the interchange. 
           [0020]      FIG. 7  shows the arrangement of road surfaces in a seventh embodiment, which has one loop ramp and requires as few as three bridges; 
           [0021]      FIG. 8  shows an eighth embodiment, which has one loop ramp and requires as few as three bridges. 
           [0022]      FIG. 9  shows the arrangement of road surfaces in a ninth embodiment, which has one loop ramp and requires as few as three bridges; 
           [0023]      FIG. 10  shows a tenth embodiment of the invention, which has one loop ramp and requires as few as three bridges. 
           [0024]      FIG. 11  is a plan view schematic of the arrangement of road surfaces in an eleventh embodiment, which has no loop ramps and requires as few as four bridges; 
           [0025]      FIG. 12  shows a twelfth embodiment of the invention, which has no loop ramps and requires as few as four bridges. 
           [0026]      FIG. 13  is a plan view schematic showing a possible arrangement of overpasses and underpasses for the first embodiment of the invention; 
           [0027]      FIG. 14  is a plan view schematic showing a possible arrangement of overpasses and underpasses for the second embodiment of the invention. 
           [0028]      FIG. 15  is a plan view schematic showing a possible arrangement of overpasses and underpasses for the third embodiment of the invention; 
           [0029]      FIG. 16  is a plan view schematic showing a possible arrangement of overpasses and underpasses for the fourth embodiment of the invention. 
           [0030]      FIG. 17  is a plan view schematic showing a possible arrangement of overpasses and underpasses for the fifth embodiment of the invention; 
           [0031]      FIG. 18  is a plan view schematic showing a possible arrangement of overpasses and underpasses for the sixth embodiment of the invention. 
           [0032]      FIG. 19  is a plan view schematic showing a possible arrangement of overpasses and underpasses for the seventh embodiment of the invention; 
           [0033]      FIG. 20  is a plan view schematic showing a possible arrangement of overpasses and underpasses for the eighth embodiment of the invention. 
           [0034]      FIG. 21  is a plan view schematic showing a possible arrangement of overpasses and underpasses for the ninth embodiment of the invention; 
           [0035]      FIG. 22  is a plan view schematic showing a possible arrangement of overpasses and underpasses for the tenth embodiment of the invention. 
           [0036]      FIG. 23  is a plan view schematic showing a possible arrangement of overpasses and underpasses for the eleventh embodiment of the invention; 
           [0037]      FIG. 24  is a plan view schematic showing a possible arrangement of overpasses and underpasses for the twelfth embodiment of the invention. 
           [0038]      FIG. 25  is a plan view schematic showing another possible arrangement of overpasses and underpasses for the first embodiment of the invention; 
           [0039]      FIG. 26  is a plan view schematic showing another possible arrangement of overpasses and underpasses for the second embodiment of the invention. 
           [0040]      FIG. 27  is a plan view schematic showing another possible arrangement of overpasses and underpasses for the third embodiment of the invention; 
           [0041]      FIG. 28  is a plan view schematic showing another possible arrangement of overpasses and underpasses for the fourth embodiment of the invention. 
           [0042]      FIG. 29  is a plan view schematic showing another possible arrangement of overpasses, underpasses, and right-turn ramps for the third embodiment of the invention; 
           [0043]      FIG. 30  is a plan view schematic showing another possible arrangement of overpasses, underpasses, and right-turn ramps for the fourth embodiment of the invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0044]    The inventive matter of the present invention is the arrangement of road surfaces relative to one another. Specific geometric features such as the horizontal and vertical alignments are not claimed as the inventive matter in this invention. As with any interchange configuration, a practitioner with ordinary skill in the art of geometric design of roadways will determine the most appropriate geometry to apply to the various embodiments of this invention by considering relevant design standards and design criteria particular to a given site of interest. 
         [0045]    It will be obvious to the practitioner of ordinary skill in the art of geometric design of roadways that, in any of the embodiments of this invention, one or more road surfaces may be omitted as desired by the practitioner utilizing the current invention; in addition, it will be obvious that one or more road surfaces may be added as desired by the practitioner utilizing the current invention. Such modifications are commonly made to standard interchange configurations, such as those mentioned in the accounting of prior art above. 
         [0046]    Note that in the descriptions that follow, it is assumed that the invention is to be applied to roads where the convention is for traffic to keep to the right. It will be obvious to a person of ordinary skill in the art how to modify the description when the invention is to be applied instead to roads where the convention is for traffic to keep to the left. 
         [0047]    No right-turn ramps are drawn in the schematics of  FIGS. 1 to 12 . It will be obvious to a practitioner with ordinary skill in the art of geometric design of roadways how best to add right-turn ramps to any embodiment of the present invention. Of the numerous interchange configurations with right-side exits and entrances only that have been developed, there is a wide variety of different arrangements of mainlines and left-turn ramps relative to one another, and the diversity of configurations practitioners have devised, and continue to devise, is an indication that devising such arrangements is not obvious; however, there is a much smaller variety of feasible arrangements of right-turn ramps relative to the mainlines and left-turn ramps in interchanges with right-side exits and entrances only. Thus, it is obvious to the practitioner of ordinary skill how to devise such arrangements. Where the exits for the right-turn and left-turn ramps are located along substantially the same length of road, a right-side exit to a right-turn ramp can either be located to the right or the left of the exit for the adjacent left-turn ramp, and where the entrances for the right-turn and left-turn ramps are located along substantially the same length of road, a right-side entrance from a right-turn ramp can either be located to the right or the left of the entrance for the adjacent left-turn ramp. Clearly, there are very few possible arrangements. Because it is obvious to a practitioner of ordinary skill how to best arrange right-turn ramps in interchanges with right-side exits and entrances, and because there are numerous existing constructed precedents of the already scarce number of different arrangements or right-turn ramps in various interchanges with right-side exits and entrances, right-turn ramps have not been included in  FIGS. 1 to 12 . 
         [0048]      FIGS. 13 through 30  show several embodiments of the present invention with possible arrangements of right-turn ramps. The arrangements of right-turn ramps in  FIGS. 13 through 28  are the most common arrangements;  FIGS. 29 and 30  show possible alternative arrangements where the exits to and entrances from two right-turn ramps are located to the left of the adjacent left-turn exits and entrances, from the perspective of a driver traveling to, along, and exiting from the right-turn ramp. A similar arrangement of right turn ramps is seen in the turbine interchange of Belgian Pat. No. 638,746 and No. 641,129. However, all of the embodiments illustrated in  FIGS. 13 through 30  may be constructed with a variety of arrangements of right-turn ramps other than those illustrated. As described above, an exit to a given right-turn ramp can either be located to the right or the left of the exit for the adjacent left-turn ramp, and an entrance from a right-turn ramp can either be located to the right or the left of the entrance for the adjacent left-turn ramp. 
         [0049]    In the following descriptions, three abbreviations are used: ‘RS’ stands for ‘road surface’, ‘RSs’ stands for ‘road surfaces’, while ‘GSC’ stands for ‘grade-separated crossing’. 
         [0050]      FIG. 1  is a plan view schematic of the arrangement of roadways in a first embodiment of the invention. This embodiment has two loop ramps and requires as few as two bridges. RSs  1 ,  2 ,  3 , and  4  are commonly called mainlines. RS  1  is provided for through traffic traveling from the extremity of the junction  37  to extremity of the junction  38 . RS  2  is provided for through traffic traveling from the extremity of the junction  38  to extremity of the junction  37 . RS  3  is provided for through traffic traveling from the extremity of the junction  39  to extremity of the junction  40 . RS  4  is provided for through traffic traveling from the extremity of the junction  40  to extremity of the junction  39 . 
         [0051]    RSs  5 ,  6 ,  7 , and  8  are commonly called left-turn ramps. RS  5  is provided for through traffic traveling from the extremity of the junction  37  to extremity of the junction  40 . RS  6  is provided for through traffic traveling from the extremity of the junction  38  to extremity of the junction  39 . RS  7  is provided for through traffic traveling from the extremity of the junction  39  to extremity of the junction  37 . RS  8  is provided for through traffic traveling from the extremity of the junction  40  to extremity of the junction  38 . 
         [0052]    At the extremity of the junction  37 , RS  1  is disposed laterally between RS  2  and RS  5 , and RS  2  is disposed laterally between RS  7  and RS  1 . At the extremity of the junction  38 , RS  1  is disposed laterally between RS  2  and RS  8 , and RS  2  is disposed laterally between RS  6  and RS  1 . At the extremity of the junction  39 , RS  4  is disposed laterally between RS  6  and RS  3 , and RS  3  is disposed laterally between RS  4  and RS  7 . At the extremity of the junction  40 , RS  3  is disposed laterally between RS  5  and RS  4 , and RS  4  is disposed laterally between RS  3  and RS  8 . 
         [0053]    The above description of RSs  1  through  8  also applies to  FIGS. 2 through 30 . 
         [0054]    Note again that specific geometric features such as horizontal and vertical alignments are not claimed as the inventive matter in this invention. The arrangements of road surfaces are defined by their positions relative to one another—for example, in the embodiment of  FIG. 1 , RS  1 , at the extremity of the junction  37 , is disposed laterally between RS  2  and RS  5 , and at the extremity of the junction  38 , it is disposed laterally between RS  2  and RS  8 , and between the extremities of the junction  37  and  38 , it has grade-separated crossing with RSs  8 ,  4 ,  3 ,  7 ,  5 , and  6 , and these grade-separated crossings occur in a particular order relative to one another. Note also that the phrase “disposed laterally between” in this patent does not imply an identical vertical elevation. For example, in the embodiment of  FIG. 1 , at the extremity of the junction  37 , RS  1  may be at a vertical elevation distinct from that of RS  2  and RS  5 . In most cases, a practitioner constructing the embodiment will place RS  1  at a vertical elevation substantially similar to that of RS  2  and RS  5 ; however, there may be cases where it is preferred not to do so. This kind of practice is also well-known to practitioners of the art of geometric design of roadways, and numerous interchanges of various configurations have been thus constructed. 
         [0055]    RS  1  intersects with RS  4  at GSC  9 ; RS  1  intersects with RS  3  at GSC  10 ; RS  2  intersects with RS  3  at GSC  11 ; RS  2  intersects with RS  4  at GSC  12 ; RS  5  intersects with RS  4  at GSC  13 ; RS  5  intersects with RS  3  at GSC  14 ; RS  6  intersects with RS  3  at GSC  15 ; RS  6  intersects with RS  4  at GSC  16 ; RS  1  intersects with RS  5  at GSC  17 ; RS  1  intersects with RS  6  at GSC  18 ; RS  2  intersects with RS  6  at GSC  19 ; and RS  2  intersects with RS  5  at GSC  20 . 
         [0056]    The above description of GSCs  9  through  20  also applies to  FIGS. 2 through 12 . Note that RSs  1  through  6  are arranged, relative to each other, in the same arrangement in all embodiments of the present invention. The various embodiments of the present invention are formed by providing different arrangements of other RSs, such as  7 ,  8 , and others described below, relative to RSs  1  through  6 . 
         [0057]    RS  1  intersects with RS  8  at GSC  21 ; RS  1  intersects with RS  7  at GSC  22 ; RS  2  intersects with RS  7  at GSC  23 ; RS  2  intersects with RS  8  GSC  24 ; RS  5  intersects with RS  8  at GSC  25 ; RS  5  intersects with RS  7  at GSC  26 ; RS  6  intersects with RS  7  at GSC  27 ; RS  6  intersects with RS  8  at GSC  28 ; RS  8  intersects with RS  8  at GSC  29 , RS  8  intersects with RS  4  at GSC  30 ; RS  8  intersects with RS  3  at GSC  31 ; RS  8  intersects with RS  7  at GSC  32 . RS  7  intersects with RS  7  at GSC  33 ; RS  7  intersects with RS  3  at GSC  34 ; RS  7  intersects with RS  4  at GSC  35 ; and RS  7  intersects with RS  8  at GSC  36 . 
         [0058]    In the following descriptions, the phrase ‘is disposed along’ stands for ‘is disposed intermediately along the length of’. For example, the sentence that follows means ‘GSC  21  is disposed intermediately along the length of RS  1  between the extremity of the junction  37  and GSC  9 ’. 
         [0059]    GSC  21  is disposed along RS  1  between the extremity of the junction  37  and GSC  9 . GSC  9  is disposed along RS  1  between GSC  21  and GSC  10 ; GSC  10  is disposed along RS  1  between GSC  9  and GSC  22 ; GSC  22  is disposed along RS  1  between GSC  10  and GSC  17 ; and GSC  17  is disposed along RS  1  between GSC  17  and GSC  18 . SC  19  is disposed along RS  2  between the extremity of the junction  38  and GSC  20 ; GSC  20  is disposed along RS  2  between GSC  19  and GSC  23 ; GSC  23  is disposed along RS  2  between GSC  11  and GSC  23 ; GSC  11  is disposed along RS  2  between GSC  23  and GSC  12 ; and GSC  12  is disposed along RS  2  between GSC  11  and GSC  24 . GSC  25  is disposed along RS  5  between the extremity of the junction  37  and GSC  13 ; GSC  13  is disposed along RS  5  between GSC  25  and GSC  14 ; GSC  14  is disposed along RS  5  between GSC  13  and GSC  26 ; GSC  26  is disposed along RS  5  between GSC  14  and GSC  17 ; and GSC  17  is disposed along RS  5  between GSC  26  and GSC  20 . GSC  19  is disposed along RS  6  between the extremity of the junction  38  and GSC  18 ; GSC  17  is disposed along RS  6  between GSC  19  and GSC  27 ; GSC  27  is disposed along RS  6  between GSC  17  and GSC  15 ; GSC  15  is disposed along RS  6  between GSC  27  and GSC  16 ; and GSC  16  is disposed along RS  6  between GSC  15  and GSC  28 . GSC  32  is disposed along RS  7  between the extremity of the junction  39  and GSC  27 ; GSC  27  is disposed along RS  7  between GSC  32  and GSC  26 ; GSC  26  is disposed along RS  7  between GSC  27  and GSC  22 ; GSC  22  is disposed along RS  7  between GSC  26  and GSC  23 ; GSC  23  is disposed along RS  7  between GSC  22  and GSC  33 ; GSC  33  is disposed along RS  7  between GSC  23  and GSC  34 ; GSC  34  is disposed along RS  7  between GSC  33  and GSC  35 ; and GSC  35  is disposed along RS  7  between GSC  34  and GSC  36 . GSC  36  is disposed along RS  8  between extremity of the junction  40  and GSC  24 ; GSC  24  is disposed along RS  8  between GSC  36  and GSC  21 ; GSC  21  is disposed along RS  8  between GSC  24  and GSC  25 ; GSC  25  is disposed along RS  8  between GSC  21  and GSC  28 ; GSC  28  is disposed along RS  8  between GSC  25  and GSC  29 ; GSC  29  is disposed along RS  8  between GSC  28  and GSC  30 ; GSC  30  is disposed along RS  8  between GSC  29  and GSC  31 ; and GSC  31  is disposed along RS  8  between GSC  30  and GSC  32 . 
         [0060]    The above description of  FIG. 1  applies also to  FIG. 2 .  FIG. 2  is a plan view schematic of the arrangement of roadways in a second embodiment of the invention. This embodiment has two loop ramps and requires as few as two bridges. This embodiment is based on a horizontal reflection of the drawing of  FIG. 1 . 
         [0061]      FIG. 3  is a plan view schematic of the arrangement of roadways in a third embodiment of the invention. This embodiment has no loop ramps and requires as few as three bridges. 
         [0062]    RS  7  intersects with RS  6  at GSC  41 ; RS  7  intersects with RS  5  at GSC  42 ; RS  7  intersects with RS  1  at GSC  43 ; RS  7  intersects with RS  2  at GSC  44 ; RS  7  intersects with RS  3  at GSC  45 ; and RS  7  intersects with RS  4  at GSC  46 . RS  8  intersects with RS  4  at GSC  47 ; RS  8  intersects with RS  3  at GSC  48 ; RS  8  intersects with RS  2  at GSC  49 ; RS  8  intersects with RS  1  at GSC  50 ; RS  8  intersects with RS  5  at GSC  51 ; and RS  8  intersects with RS  6  at GSC  52 . 
         [0063]    GSC  9  is disposed along RS  1  between extremity of the junction  37  and GSC  10 ; GSC  10  is disposed along RS  1  between GSC  9  and GSC  43 ; GSC  43  is disposed along RS  1  between GSC  10  and GSC  50 ; GSC  50  is disposed along RS  1  between GSC  43  and GSC  17 ; and GSC  17  is disposed along RS  1  between GSC  50  and GSC  18 . GSC  19  is disposed along RS  2  between extremity of the junction  38  and GSC  20 ; GSC  20  is disposed along RS  2  between GSC  19  and GSC  49 ; GSC  49  is disposed along RS  2  between GSC  20  and GSC  44 ; GSC  44  is disposed along RS  2  between GSC  44  and GSC  11 ; and GSC  11  is disposed along RS  2  between GSC  44  and GSC  12 . GSC  13  is disposed along RS  5  between extremity of the junction  37  and GSC  14 ; GSC  14  is disposed along RS  5  between GSC  13  and GSC  42 ; GSC  42  is disposed along RS  5  between GSC  14  and GSC  51 ; GSC  51  is disposed along RS  5  between GSC  42  and GSC  17 ; and GSC  17  is disposed along RS  5  between GSC  51  and GSC  20 . GSC  19  is disposed along RS  6  between extremity of the junction  38  and GSC  18 ; GSC  18  is disposed along RS  6  between GSC  19  and GSC  52 ; GSC  52  is disposed along RS  6  between GSC  18  and GSC  41 ; GSC  41  is disposed along RS  6  between GSC  52  and GSC  15 ; and GSC  15  is disposed along RS  6  between GSC  41  and GSC  16 . GSC  41  is disposed along RS  7  between extremity of the junction  39  and GSC  42 ; GSC  42  is disposed along RS  7  between GSC  41  and GSC  43 ; GSC  43  is disposed along RS  7  between GSC  42  and GSC  44 ; GSC  44  is disposed along RS  7  between GSC  43  and GSC  45 ; and GSC  45  is disposed along RS  7  between GSC  44  and GSC  46 . GSC  47  is disposed along RS  8  between extremity of the junction  40  and GSC  48 ; GSC  48  is disposed along RS  8  between GSC  47  and GSC  49 ; GSC  49  is disposed along RS  8  between GSC  48  and GSC  50 ; GSC  50  is disposed along RS  8  between GSC  49  and GSC  51 ; and GSC  51  is disposed along RS  8  between GSC  50  and GSC  52 . 
         [0064]    The above description of  FIG. 3  applies also to  FIG. 4 .  FIG. 4  is a plan view schematic of the arrangement of roadways in a fourth embodiment of the invention. This embodiment has no loop ramps and requires as few as three bridges. This embodiment is based on a horizontal reflection of the drawing of  FIG. 3 . 
         [0065]      FIG. 5  is a plan view schematic of the arrangement of roadways in a fifth embodiment of the invention. This embodiment has no loop ramps and requires as few as three bridges. U-turn ramps are also provided for each leg of the interchange. 
         [0066]    RS  7  intersects with RS  6  at GSC  41 ; RS  7  intersects with RS  5  at GSC  42 ; RS  7  intersects with RS  1  at GSC  43 ; RS  7  intersects with RS  2  at GSC  44 ; RS  7  intersects with RS  3  at GSC  45 ; and RS  7  intersects with RS  4  at GSC  46 . RS  8  intersects with RS  4  at GSC  47 ; RS  8  intersects with RS  3  at GSC  48 ; RS  8  intersects with RS  2  at GSC  49 , RS  8  intersects with RS  1  at GSC  50 ; RS  8  intersects with RS  5  at GSC  51 ; and RS  8  intersects with RS  6  at GSC  52 . 
         [0067]    RSs  53 ,  54 ,  55 , and  56  are commonly called U-turn ramps. RS  53  is provided for U-turn traffic traveling from the extremity of the junction  37  and returning to the extremity of the junction  37 . RS  54  is provided for U-turn traffic traveling from the extremity of the junction  38  and returning to the extremity of the junction  38 . RS  55  is provided for U-turn traffic traveling from the extremity of the junction  39  and returning to the extremity of the junction  39 . RS  56  is provided for U-turn traffic traveling from the extremity of the junction  40  and returning to the extremity of the junction  40 . 
         [0068]    RS  53  intersects with RS  55  at GSC  57 ; RS  53  intersects with RS  4  at GSC  58 ; RS  53  intersects with RS  3  at GSC  59 ; RS  53  intersects with RS  55  at GSC  60 ; RS  53  intersects with RS  7  at GSC  61 ; RS  53  intersects with RS  8  at GSC  62 ; RS  53  intersects with RS  1  at GSC  63 ; RS  53  intersects with RS  2  at GSC  64 ; RS  53  intersects with RS  8  at GSC  65 ; RS  53  intersects with RS  7  at GSC  66 ; RS  53  intersects with RS  55  at GSC  67 ; RS  53  intersects with RS  3  at GSC  68 ; RS  53  intersects with RS  4  at GSC  69 ; and RS  53  intersects with RS  55  at GSC  70 . RS  54  intersects with RS  2  at GSC  71 ; and RS  54  intersects with RS  1  at GSC  72 . RS  55  intersects with RS  6  at GSC  73 ; RS  55  intersects with RS  5  at GSC  74 ; RS  55  intersects with RS  1  at GSC  75 ; RS  55  intersects with RS  2  at GSC  76 ; RS  55  intersects with RS  3  at GSC  77 ; RS  55  intersects with RS  4  at GSC  78 ; RS  55  intersects with RS  2  at GSC  79 ; RS  55  intersects with RS  1  at GSC  80 ; RS  55  intersects with RS  5  at GSC  81 ; and RS  55  intersects with RS  6  at GSC  82 . RS  56  intersects with RS  4  at GSC  83 ; and RS  56  intersects with RS  3  at GSC  84 . 
         [0069]    GSC  80  is disposed along RS  1  between extremity of the junction  37  and GSC  9 ; GSC  9  is disposed along RS  1  between GSC  80  and GSC  10 ; GSC  10  is disposed along RS  1  between GSC  9  and GSC  75 ; GSC  75  is disposed along RS  1  between GSC  10  and GSC  62 ; GSC  62  is disposed along RS  1  between GSC  75  and GSC  50 ; GSC  50  is disposed along RS  1  between GSC  62  and GSC  63 ; GSC  63  is disposed along RS  1  between GSC  50  and GSC  17 ; and GSC  17  is disposed along RS  1  between GSC  63  and GSC  18 . GSC  71  is disposed along RS  2  between extremity of the junction  38  and GSC  19 ; GSC  19  is disposed along RS  2  between GSC  71  and GSC  20 ; GSC  20  is disposed along RS  2  between GSC  19  and GSC  64 ; GSC  64  is disposed along RS  2  between GSC  20  and GSC  49 ; GSC  49  is disposed along RS  2  between GSC  64  and GSC  44 ; GSC  44  is disposed along RS  2  between GSC  49  and GSC  76 ; GSC  76  is disposed along RS  2  between GSC  44  and GSC  11 ; GSC  11  is disposed along RS  2  between GSC  76  and GSC  12 ; and GSC  12  is disposed along RS  2  between GSC  11  and GSC  79 . GSC  15  is disposed along RS  3  between extremity of the junction  39  and GSC  14 ; GSC  14  is disposed along RS  3  between GSC  15  and GSC  59 ; GSC  59  is disposed along RS  3  between GSC  14  and GSC  10 ; GSC  10  is disposed along RS  3  between GSC  59  and GSC  11 ; GSC  11  is disposed along RS  3  between GSC  10  and GSC  68 ; GSC  68  is disposed along RS  3  between GSC  11  and GSC  77 ; GSC  77  is disposed along RS  3  between GSC  68  and GSC  45 ; GSC  45  is disposed along RS  3  between GSC  77  and GSC  48 ; and GSC  48  is disposed along RS  3  between GSC  45  and GSC  84 . GSC  83  is disposed along RS  4  between extremity of the junction  40  and GSC  47 ; GSC  47  is disposed along RS  4  between GSC  83  and GSC  46 ; GSC  46  is disposed along RS  4  between GSC  47  and GSC  78 ; GSC  78  is disposed along RS  4  between GSC  46  and GSC  69 ; GSC  69  is disposed along RS  4  between GSC  78  and GSC  12 ; GSC  12  is disposed along RS  4  between GSC  69  and GSC  9 ; GSC  9  is disposed along RS  4  between GSC  12  and GSC  58 ; GSC  58  is disposed along RS  4  between GSC  9  and GSC  13 ; and GSC  13  is disposed along RS  4  between GSC  58  and GSC  16 . GSC  41  is disposed along RS  7  between extremity of the junction  39  and GSC  42 ; GSC  42  is disposed along RS  7  between GSC  41  and GSC  61 ; GSC  61  is disposed along RS  7  between GSC  42  and GSC  43 ; GSC  43  is disposed along RS  7  between GSC  61  and GSC  44 ; GSC  44  is disposed along RS  7  between 
         [0070]    GSC  43  and GSC  66 ; GSC  66  is disposed along RS  7  between GSC  44  and GSC  45 ; and GSC  45  is disposed along RS  7  between GSC  66  and GSC  46 . GSC  47  is disposed along RS  8  between extremity of the junction  40  and GSC  48 ; GSC  48  is disposed along RS  8  between GSC  47  and GSC  65 ; GSC  65  is disposed along RS  8  between GSC  48  and GSC  49 ; GSC  49  is disposed along RS  8  between GSC  65  and GSC  50 ; GSC  50  is disposed along between GSC  49  and GSC  62 ; GSC  62  is disposed along RS  8  between GSC  50  and GSC  51 ; and GSC  51  is disposed along RS  8  between GSC  62  and GSC  52 . 
         [0071]    The above description of  FIG. 5  applies also to  FIG. 6 .  FIG. 6  is a plan view schematic of the arrangement of roadways in a sixth embodiment of the invention. This embodiment has no loop ramps and requires as few as three bridges. U-turn ramps are also provided for each leg of the interchange. This embodiment is based on a horizontal reflection of the drawing of  FIG. 5 . 
         [0072]      FIG. 7  is a plan view schematic of the arrangement of roadways in a seventh embodiment of the invention. This embodiment has one loop ramp and requires as few as three bridges. 
         [0073]    RS  1  intersects with RS  8  at GSC  21 ; RS  1  intersects with RS  7  at GSC  22 ; RS  2  intersects with RS  7  at GSC  23 ; RS  2  intersects with RS  8  GSC  24 ; RS  5  intersects with RS  8  at GSC  25 ; RS  5  intersects with RS  7  at GSC  26 ; RS  6  intersects with RS  7  at GSC  27 ; RS  6  intersects with RS  8  at GSC  28 ; RS  8  intersects with RS  8  at GSC  29 ; RS  8  intersects with RS  4  at GSC  30 ; RS  8  intersects with RS  3  at GSC  31 ; RS  8  intersects with RS  7  at GSC  32 ; RS  7  intersects with RS  3  at GSC  94 ; RS  7  intersects with RS  4  at GSC  95 ; and RS  7  intersects with RS  8  at GSC  96 . 
         [0074]    GSC  21  is disposed along RS  1  between the extremity of the junction  37  and GSC  9 ; GSC  9  is disposed along RS  1  between GSC  21  and GSC  10 ; GSC  10  is disposed along RS  1  between GSC  9  and GSC  22 ; GSC  22  is disposed along RS  1  between GSC  10  and GSC  17 ; and GSC  17  is disposed along RS  1  between GSC  22  and GSC  18 . GSC  19  is disposed along RS  2  between the extremity of the junction  38  and GSC  20 ; GSC  20  is disposed along RS  2  between GSC  19  and GSC  23 ; GSC  23  is disposed along RS  2  between GSC  11  and GSC  20 ; GSC  11  is disposed along RS  2  between GSC  23  and GSC  12 ; and GSC  12  is disposed along RS  2  between GSC  11  and GSC  24 . GSC  25  is disposed along RS  5  between the extremity of the junction  37  and GSC  13 ; GSC  13  is disposed along RS  5  between GSC  25  and GSC  14 ; GSC  14  is disposed along RS  5  between GSC  13  and GSC  26 ; GSC  26  is disposed along RS  5  between GSC  14  and GSC  17 ; and GSC  17  is disposed along RS  5  between GSC  26  and GSC  20 . GSC  19  is disposed along RS  6  between the extremity of the junction  38  and GSC  18 ; GSC  17  is disposed along RS  6  between GSC  19  and GSC  27 ; GSC  27  is disposed along RS  6  between GSC  17  and GSC  15 ; GSC  15  is disposed along RS  6  between GSC  27  and GSC  16 ; and GSC  16  is disposed along RS  6  between GSC  15  and GSC  28 . GSC  32  is disposed along RS  7  between the extremity of the junction  39  and GSC  27 ; GSC  27  is disposed along RS  7  between GSC  32  and GSC  26 ; GSC  26  is disposed along RS  7  between GSC  27  and GSC  22 ; GSC  22  is disposed along RS  7  between GSC  26  and GSC  23 ; GSC  23  is disposed along RS  7  between GSC  22  and GSC  85 ; GSC  85  is disposed along RS  7  between GSC  23  and GSC  86 ; and GSC  86  is disposed along RS  7  between GSC  85  and GSC  87 . GSC  87  is disposed along RS  8  between extremity of the junction  40  and GSC  24 ; GSC  24  is disposed along RS  8  between GSC  87  and GSC  21 ; GSC  21  is disposed along RS  8  between GSC  24  and GSC  25 ; GSC  25  is disposed along RS  8  between GSC  21  and GSC  28 ; GSC  28  is disposed along RS  8  between GSC  25  and GSC  29 ; GSC  29  is disposed along RS  8  between GSC  28  and GSC  30 ; GSC  30  is disposed along RS  8  between GSC  29  and GSC  31 ; and GSC  31  is disposed along RS  8  between GSC  30  and GSC  32 . 
         [0075]    The above description of  FIG. 7  applies also to  FIG. 8 .  FIG. 8  is a plan view schematic of the arrangement of roadways in an eighth embodiment of the invention. This embodiment has one loop ramp and requires as few as three bridges. This embodiment is based on a horizontal reflection of the drawing of  FIG. 7 . 
         [0076]      FIG. 9  is a plan view schematic of the arrangement of roadways in a ninth embodiment of the invention. This embodiment has one loop ramp and requires as few as three bridges. 
         [0077]    RS  1  intersects with RS  8  at GSC  21 ; RS  1  intersects with RS  7  at GSC  92 ; RS  2  intersects with RS  7  at GSC  92 ; RS  2  intersects with RS  8  GSC  24 ; RS  5  intersects with RS  8  at GSC  25 ; RS  5  intersects with RS  7  at GSC  90 ; RS  6  intersects with RS  7  at GSC  89 ; RS  6  intersects with RS  8  at GSC  97 ; RS  8  intersects with RS  4  at GSC  98 ; RS  8  intersects with RS  3  at GSC  99 ; RS  8  intersects with RS  7  at GSC  88 ; RS  7  intersects with RS  3  at GSC  94 ; RS  7  intersects with RS  4  at GSC  95 ; and RS  7  intersects with RS  8  at GSC  96 . 
         [0078]    GSC  21  is disposed along RS  1  between the extremity of the junction  37  and GSC  9 ; GSC  9  is disposed along RS  1  between GSC  21  and GSC  10 ; GSC  10  is disposed along RS  1  between GSC  9  and GSC  91 ; GSC  91  is disposed along RS  1  between GSC  10  and GSC  17 ; and GSC  17  is disposed along RS  1  between GSC  91  and GSC  18 . GSC  19  is disposed along RS  2  between the extremity of the junction  38  and GSC  20 ; GSC  20  is disposed along RS  2  between GSC  19  and GSC  92 ; GSC  92  is disposed along RS  2  between GSC  11  and GSC  20 ; GSC  11  is disposed along RS  2  between GSC  92  and GSC  12 ; and GSC  12  is disposed along RS  2  between GSC  11  and GSC  24 . GSC  25  is disposed along RS  5  between the extremity of the junction  37  and GSC  13 ; GSC  13  is disposed along RS  5  between GSC  25  and GSC  14 ; GSC  14  is disposed along RS  5  between GSC  13  and GSC  90 ; GSC  90  is disposed along RS  5  between GSC  14  and GSC  17 ; and GSC  17  is disposed along RS  5  between GSC  26  and GSC  20 . GSC  19  is disposed along RS  6  between the extremity of the junction  38  and GSC  18 ; GSC  17  is disposed along RS  6  between GSC  19  and GSC  89 ; GSC  89  is disposed along RS  6  between GSC  17  and GSC  15 ; GSC  15  is disposed along RS  6  between GSC  89  and GSC  16 ; and GSC  16  is disposed along RS  6  between GSC  15  and GSC  97 . GSC  88  is disposed along RS  7  between the extremity of the junction  39  and GSC  89 ; GSC  89  is disposed along RS  7  between GSC  90  and GSC  89 ; GSC  90  is disposed along RS  7  between GSC  89  and GSC  91 ; GSC  91  is disposed along RS  7  between GSC  90  and GSC  92 ; GSC  92  is disposed along RS  7  between GSC  91  and GSC  93 ; GSC  93  is disposed along RS  7  between GSC  92  and GSC  94 ; GSC  94  is disposed along RS  7  between GSC  93  and GSC  95 ; and GSC  95  is disposed along RS  7  between GSC  94  and GSC  96 . GSC  96  is disposed along RS  8  between extremity of the junction  40  and GSC  24 ; GSC  24  is disposed along RS  8  between GSC  87  and GSC  21 ; GSC  21  is disposed along RS  8  between GSC  24  and GSC  25 ; GSC  25  is disposed along RS  8  between GSC  21  and GSC  97 ; GSC  97  is disposed along RS  8  between GSC  25  and GSC  98 ; GSC  98  is disposed along RS  8  between GSC  97  and GSC  99 ; and GSC  99  is disposed along RS  8  between GSC  98  and GSC  88 . 
         [0079]    The above description of  FIG. 9  applies also to  FIG. 10 .  FIG. 10  is a plan view schematic of the arrangement of roadways in a tenth embodiment of the invention. This embodiment has one loop ramp and requires as few as three bridges. This embodiment is based on a horizontal reflection of the drawing of  FIG. 9 . 
         [0080]      FIG. 11  is a plan view schematic of the arrangement of roadways in an eleventh embodiment of the invention. This embodiment has no loop ramps and requires as few as four bridges. 
         [0081]    RS  7  intersects with RS  6  at GSC  41 ; RS  7  intersects with RS  5  at GSC  42 ; RS  7  intersects with RS  1  at GSC  43 ; RS  7  intersects with RS  2  at GSC  44 ; RS  7  intersects with RS  3  at GSC  85 ; and RS  7  intersects with RS  4  at GSC  86 ; and RS  7  intersects with RS  8  at GSC  87 . RS  8  intersects with RS  6  at GSC  97 ; RS  8  intersects with RS  2  at GSC  24 ; RS  8  intersects with RS  1  at GSC  21 ; RS  8  intersects with RS  5  at GSC  25 ; RS  8  intersects with RS  6  at GSC  97 ; RS  8  intersects with RS  4  at GSC  98 ; RS  8  intersects with RS  3  at GSC  99 ; and RS  8  intersects with RS  7  at GSC  88 . 
         [0082]    GSC  21  is disposed along RS  1  between extremity of the junction  37  and GSC  9 ; GSC  9  is disposed along RS  1  between GSC  21  and GSC  10 ; GSC  10  is disposed along RS  1  between GSC  9  and GSC  43 ; GSC  43  is disposed along RS  1  between GSC  10  and GSC  17 ; and GSC  17  is disposed along RS  1  between GSC  50  and GSC  18 . GSC  19  is disposed along RS  2  between extremity of the junction  38  and GSC  20 ; GSC  20  is disposed along RS  2  between GSC  19  and GSC  49 ; GSC  49  is disposed along RS  2  between GSC  20  and GSC  44 ; GSC  44  is disposed along RS  2  between GSC  44  and GSC  11 ; GSC  11  is disposed along RS  2  between GSC  44  and GSC  12 ; and GSC  12  is disposed along RS  2  between GSC  11  and GSC  24 . GSC  25  is disposed along RS  5  between extremity of the junction  37  and GSC  13 ; GSC  13  is disposed along RS  5  between GSC  25  and GSC  14 ; GSC  14  is disposed along RS  5  between GSC  13  and GSC  42 ; GSC  42  is disposed along RS  5  between GSC  14  and GSC  17 ; and GSC  17  is disposed along RS  5  between GSC  42  and GSC  20 . GSC  19  is disposed along RS  6  between extremity of the junction  38  and GSC  18 ; GSC  18  is disposed along RS  6  between GSC  19  and GSC  41 ; GSC  41  is disposed along RS  6  between GSC  52  and GSC  15 ; GSC  15  is disposed along RS  6  between GSC  41  and GSC  16 ; and GSC  16  is disposed along RS  6  between 
         [0083]    GSC  15  and GSC  97 . GSC  88  is disposed along RS  7  between extremity of the junction  39  and GSC  41 ; GSC  41  is disposed along RS  7  between GSC  88  and GSC  42 ; GSC  42  is disposed along RS  7  between GSC  41  and GSC  43 ; GSC  43  is disposed along RS  7  between GSC  42  and GSC  44 ; GSC  44  is disposed along RS  7  between GSC  43  and GSC  85 ; GSC  85  is disposed along RS  7  between GSC  44  and GSC  86 ; and GSC  86  is disposed along RS  7  between GSC  85  and GSC  87 . GSC  87  is disposed along RS  8  between extremity of the junction  40  and GSC  24 ; GSC  24  is disposed along RS  8  between GSC  87  and GSC  21 ; GSC  21  is disposed along RS  8  between GSC  24  and GSC  25 ; GSC  25  is disposed along RS  8  between GSC  21  and GSC  97 ; GSC  97  is disposed along RS  8  between GSC  21  and GSC  98 ; GSC  98  is disposed along RS  8  between GSC  97  and GSC  99 ; and GSC  99  is disposed along RS  8  between GSC  98  and GSC  88 . 
         [0084]    The above description of  FIG. 11  applies also to  FIG. 12 .  FIG. 12  is a plan view schematic of the arrangement of roadways in a twelfth embodiment of the invention. This embodiment has no loop ramps and requires as few as four bridges. This embodiment is based on a horizontal reflection of the drawing of  FIG. 11 . 
         [0085]    Regarding all of the embodiments shown in  FIGS. 13 to 30 , it will be obvious to a practitioner with ordinary skill in the art of geometric design of roadways how to design an appropriate geometry which uses additional bridges if the particular requirements of a given site require such a geometry. For example, where a freeway has a very wide median, it may be more appropriate to place the freeway on at least two bridges rather than one very wide bridge. It will also be obvious to such a practitioner how to modify the arrangements of overpasses and underpasses so a particular group of RSs is placed on an overpass rather than an underpass, for example. It will also be obvious to a person of ordinary skill that each of the embodiments may be constructed with arrangements of overpasses and underpasses different from those shown in the drawings. For example, where a first RS is shown as extending underneath other RSs, it is also possible to instead extend the first RS over the other RSs. In addition, it will be obvious to a person of ordinary skill that adjacent RSs in the embodiments may be connected to each other, or may be separated, and may have any vertical alignment, horizontal alignment, or cross-sectional characteristics desired. For example, RS  3  may adjoin RS  4 , and the boundary between the two RSs may simply be marked with painted lines, or alternatively, RS  3  may be separated from RS  4  by a wide grassy median; and RS  3  may have a curving horizontal or vertical alignment if required; and RS  3  may have one travel lane or several travel lanes. 
         [0086]    It will also be obvious to a practitioner with ordinary skill in the art of geometric design of roadways how to interpret  FIGS. 13 to 30 . In order to minimize clutter in these drawings, so-called ‘hidden lines’ have not been drawn. A practitioner with ordinary skill will nevertheless understand, for example, that in the embodiment of  FIG. 13 , RS  3  extends continuously from the extremity of the junction  39  to the extremity of the junction  40 . Though the drawn lines representing the outer edges of RS  3  do not intersect the drawn lines representing the edges of RSs  8 ,  6 ,  5 ,  1 ,  2 , and  7 , it will be obvious to a person of ordinary skill that RS  3  continues underneath RSs  8 ,  6 ,  5 ,  1 ,  2 , and  7 . 
         [0087]      FIG. 13  shows a possible arrangement of overpasses and underpasses for the first embodiment of the invention. Arrows show the direction of traffic flow along the different RSs in the interchange (assuming right-hand traffic). In this figure, right-turn ramps are shown. These are RSs  100  through  103 . RS  100  is provided for traffic moving from the extremity of the junction  37  to the extremity of the junction  39 . RS  101  is provided for traffic moving from the extremity of the junction  38  to the extremity of the junction  40 . RS  102  is provided for traffic moving from the extremity of the junction  39  to the extremity of the junction  38 . RS  103  is provided for traffic moving from the extremity of the junction  40  to the extremity of the junction  37 . The foregoing description of RSs  100  through  103  also applies to  FIGS. 14 through 30 . In the version of the embodiment shown, two bridges are required, a first bridge  104  and a second bridge  105 . Other arrangements of overpasses and underpasses are also possible; for example, RSs  8  (where it is laterally adjacent to RS  1 ),  1 ,  2 ,  5 ,  6 , and  7  (where it is laterally adjacent to RS  2 ) can pass underneath RSs  8  (where it is laterally adjacent to RS  4 ),  4 ,  3 , and  7  (where it is laterally adjacent to RS  3 ). In addition, if the particular constraints of a real-world site require it, the embodiment can be constructed with more than two bridges. (See  FIG. 25  for one such example.) The above description of  FIG. 13  applies also to  FIG. 14 , except that  FIG. 14  shows a possible arrangement of overpasses and underpasses for the second embodiment of the invention. 
         [0088]      FIG. 15  shows a possible arrangement of overpasses and underpasses for the third embodiment of the invention. Arrows show the direction of traffic flow along the different RSs in the interchange (assuming right-hand traffic). hi the version of the embodiment shown, three bridges are required, a first bridge  104 , a second bridge  106 , and a third bridge  107 . Other arrangements of overpasses and underpasses are also possible. In addition, if the particular constraints of a real-world site require it, the embodiment can be constructed with more than three bridges. (See  FIG. 27  for one such example.) The above description of  FIG. 15  applies also to  FIG. 16 , except that  FIG. 15  shows a possible arrangement of overpasses and underpasses for the fourth embodiment of the invention.  FIG. 17  shows a possible arrangement of overpasses and underpasses for the fifth embodiment of the invention. Arrows show the direction of traffic flow along the different RSs in the interchange (assuming right-hand traffic). In the version of the embodiment shown, three bridges are required, a first bridge  104 , a second bridge  106 , and a third bridge  107 . Other arrangements of overpasses and underpasses are also possible. In addition, if the particular constraints of a real-world site require it, the embodiment can be constructed with more than three bridges. As mentioned previously, one or more roadways may be omitted from any of the embodiments of this invention. In particular, when constructing the fifth embodiment, it may be preferred to omit one or more of the U-turn ramps. The above description of  FIG. 17  applies also to  FIG. 18 , except that  FIG. 18  shows a possible arrangement of overpasses and underpasses for the sixth embodiment of the invention. 
         [0089]      FIG. 19  shows a possible arrangement of overpasses and underpasses for the seventh embodiment of the invention. hi the version of the embodiment shown, three bridges are required, a first bridge  104 , a second bridge  105 , and a third bridge  107 . Other arrangements of overpasses and underpasses are also possible. In addition, if the particular constraints of a real-world site require it, the embodiment can be constructed with more than three bridges. The above description of  FIG. 19  applies also to  FIG. 20 , except that  FIG. 20  shows a possible arrangement of overpasses and underpasses for the eighth embodiment of the invention. 
         [0090]      FIG. 21  shows a possible arrangement of overpasses and underpasses for the ninth embodiment of the invention. In the version of the embodiment shown, three bridges are required, a first bridge  104 , a second bridge  105 , and a third bridge  108 . Other arrangements of overpasses and underpasses are also possible. In addition, if the particular constraints of a real-world site require it, the embodiment can be constructed with more than three bridges. The above description of  FIG. 21  applies also to  FIG. 22 , except that  FIG. 22  shows a possible arrangement of overpasses and underpasses for the tenth embodiment of the invention. 
         [0091]      FIG. 23  shows a possible arrangement of overpasses and underpasses for the eleventh embodiment of the invention. In the version of the embodiment shown, four bridges are required, a first bridge  104 , a second bridge  106 , a third bridge  107 , and a fourth bridge  108 . Other arrangements of overpasses and underpasses are also possible. In addition, if the particular constraints of a real-world site require it, the embodiment can be constructed with more than three bridges. The above description of  FIG. 23  applies also to  FIG. 24 , except that  FIG. 24  shows a possible arrangement of overpasses and underpasses for the twelfth embodiment of the invention. 
         [0092]      FIG. 25  shows another possible arrangement of overpasses and underpasses for the first embodiment of the invention. In the version of the embodiment shown, three bridges are required, a first bridge  104 , a second bridge  105 , and a third bridge  110 . Other arrangements of overpasses and underpasses are also possible. In addition, if the particular constraints of a real-world site require it, the embodiment can be constructed with more than three bridges. The above description of  FIG. 25  applies also to  FIG. 26 , except that  FIG. 26  shows a possible arrangement of overpasses and underpasses for the second embodiment of the invention. 
         [0093]      FIG. 27  shows another possible arrangement of overpasses and underpasses for the third embodiment of the invention.  FIG. 27  shows an exceptional example of how the third embodiment can be constructed using more than three bridges if desired. In the version of the embodiment shown, eleven bridges are required: a first bridge  104 , a second bridge  106 , a third bridge  107 , a fourth bridge  110 , a fifth bridge  111 , a sixth bridge  112 , a seventh bridge  113 , an eighth bridge  114 , a ninth bridge  115 , a tenth bridge  116 , and an eleventh bridge  117 . Other arrangements of overpasses and underpasses are also possible. In addition, if the particular constraints of a real-world site require it, the embodiment can be constructed with more bridges. The above description of  FIG. 27  applies also to  FIG. 28 , except that  FIG. 28  shows a possible arrangement of overpasses and underpasses for the fourth embodiment of the invention. 
         [0094]      FIG. 29  shows another possible arrangement of overpasses, underpasses, and right-turn ramps for the third embodiment of the invention. This embodiment is similar to that shown in  FIG. 15 ; however, the right-turn ramps  101  and  103  are arranged differently in  FIG. 29 . The exit for right-turn ramp  101  is located on the left-hand side (from the point of view of traffic approaching the exit) of the exit for left-turn ramp  6 ; similarly, the exit for right-turn ramp  103  is located on the left-hand side (from the point of view of traffic approaching the exit) of the exit for left-turn ramp  8 . The entrance to the freeway from right-turn ramp  101  is located on the left-hand side (from the point of view of traffic entering the freeway) of the entrance for left-turn ramp  5 ; similarly, the entrance to the freeway from right-turn ramp  103  is located on the left-hand side (from the point of view of traffic entering the freeway) of the entrance for left-turn ramp  7 . As noted above, it will be obvious to a practitioner with ordinary skill in the art of geometric design of roadways how best to add right-turn ramps to any embodiment of the present invention.  FIGS. 29 and 30  are provided simply to show possible arrangements where the right-turn exits on two approaches to the junction are located to the left of the left-turn exits, from the perspective of a driver approaching the exits. A similar arrangement of right turn ramps is seen in the turbine interchange of Belgian Pat. No. 638,746 and No. 641,129. The above description of  FIG. 29  applies also to  FIG. 30 , except that  FIG. 30  shows a possible arrangement of overpasses and underpasses for the fourth embodiment of the invention. 
         [0095]    It will be obvious to those skilled in the art of geometric design of roadways how to modify the embodiments of this invention by replacing one or more of the left-turn ramps with one or more left-turn ramps of different arrangements. Such ramps are often called flyover ramps, and are often given forms similar to the left-turn ramps of the ‘turbine’ or four-level directional interchange configurations mentioned above. Such modifications are commonly made when it becomes necessary to increase the capacity of an interchange. 
         [0096]    It will be obvious to those skilled in the art of transportation engineering that the configurations of road surfaces in the embodiments of this invention may also be applied to various kinds of traveled ways or lines of transportation. For example, the road surfaces of the embodiments described herein may be railroads, bicycle paths, footpaths, and so forth. 
         [0097]    Those of ordinary skill will understand and appreciate the existence of other variations, combinations, and equivalents of the specific embodiments and examples herein. The invention should therefore not be limited by the above described embodiments and examples, but by all embodiments and methods within the scope and spirit of the invention.