Unlike standard intersections, an interchange provides a free flow of vehicles, allowing them to bypass intersections and traffic lights. But sometimes interchanges can be extremely complex and consist of several levels. Below is a list of the ten most difficult road junctions in the world.

South Bay Interchange is a massive road junction in Boston, Massachusetts, USA. It was built in the late 90s as part of the Big Dig project.

A4 and E70 is a complex road transport hub located in Milan, Italy.

Eighth place in the list of the ten most difficult road junctions in the world is Xinzhuang interchange, located in Shanghai, China.

The seventh position is occupied by Higashiosaka Loop - a road transport hub located in Osaka, Japan.

The sixth line is occupied by the Interchange of I-695 and I-95 - a complex traffic intersection located in Baltimore County, Maryland, USA.

Kennedy Interchange is a road and transportation hub located on the northeastern outskirts of Louisville, Kentucky, USA. Its construction began in the spring of 1962 and was completed in 1964.

Judge Harry Pregerson Interchange is a transportation hub in Los Angeles, California, USA. It was opened in 1993 and named after federal judge Harry Pregerson.

Tom Moreland Interchange is a road junction located northeast of Atlanta, Georgia, USA. It was built between 1983 and 1987 and named after Tom Moreland, one of the leading road builders in the United States. The hub currently services about 300,000 vehicles per day.

Gravelly Hill Interchange is a complex road junction in Birmingham, England, better known by the nickname Spaghetti Junction. It was opened on May 24, 1972. It covers 12 ha and includes 4 km of connecting roads.

Puxi Viaduct is a large, six-level road junction located in the historic center of Shanghai, China.

Transport interchange- a complex of road structures (bridges, tunnels, roads) designed to minimize the intersection of traffic flows and, as a result, to increase the capacity of roads. Mostly traffic interchanges are understood as transport intersections at different levels,

Rice. 18.3. Scheme of clover-shaped traffic intersections in two levels:
a - full cloverleaf; b - pressed clover leaf; c, d, e, f, g - incomplete cloverleaf

Rice. 18.4. Schemes of ring traffic intersections in two levels:
a - turbine type; b - distribution ring with five overpasses; c - distribution ring with three overpasses; g - distribution ring with two overpasses.

Rice. 18.5. Schemes of loop-shaped traffic intersections in two levels:
a - double loop; b - improved double loop

Rice. 18.6. Scheme of cruciform traffic intersections in two levels:
a - intersection with five overpasses of the "cross" type; b - intersection with related left turns

Rice. 18.7. Diamond-shaped traffic intersections at different levels:
a - with straight left turns; b, c - with semi-direct left turns; g - in four levels

Rice. 18.8. Schemes of complex transport intersections in two levels:

a - with one semi-direct left-turn exit; b, c - with one direct left-turn exit; d - with two semi-direct left-turn exits

Rice. 18.9. Schemes of transport connections in two levels:
a, b - complete contiguity of the "pipe" type; c - complete junction with two semi-direct left-turn exits; d, e, f - incomplete adjunctions

clover crossings"+" ensuring the decoupling of traffic flows in all or in the main directions with two intersecting highways; ensuring traffic safety; relatively low cost of construction of one overpass and connecting ramps.

"-" limiting the scope of their application: a large area occupied by the interchange; significant overruns for left-turn traffic flows and U-turn flows; the need for additional measures to ensure the safe movement of pedestrians.

Roundabouts- are characterized by the greatest ease of organization of traffic, but require the construction of two to five overpasses, as well as a large area of ​​land acquisition.

Looped intersections, for example, "double loop" (Fig. 18.5, a) or "improved double loop" (Fig. 18.5, b), suit at the intersection of highways or main streets with secondary roads. “-” in addition to the need to build two overpasses, one should also attribute the insufficient provision of safe traffic conditions, since the traffic flow from the main highway flows into the flows of a secondary direction not from the right, but from the left side.

In cramped conditions of urban development, cruciform intersections are used at different levels, for example, in the form of a cross"(Fig. 18.6, a), an intersection in two levels with related left turns (Fig. 18.6, b), etc. In addition to the minimum area of ​​occupied land, this type of crossing is characterized by minimal overruns for left- and right-turn traffic, however, it requires the construction of five overpasses and excludes the possibility of a U-turn within the transport hub. Crossing in two levels with assigned left turns is often used in urban areas.

diamond junctions(see Fig. 18.7) are arranged at the intersections of equivalent highways with significant amounts of traffic in all directions. Occupying a moderate area, such interchanges practically exclude overruns for left- and right-turning traffic flows, however, the need to build a large number of overpasses determines their very high cost.

Road safety is the most important characteristic of a highway. Germany is one of the leading countries in the development of road infrastructure, as well as design standards. According to the basic law, the speed of movement on the autobahns is not limited, with the exception of some sections due to the old surface, repairs or the peculiarities of the road (city). However, statistics claim that in Germany in 2011 4,002 people died on the roads (1 person out of 22,500 inhabitants) [accident statistics in Germany], while in Russia 27,953 people (1 person out of 5,700 inhabitants) [accident statistics in Russia ].

A significant part of accidents can be avoided by choosing the right combination of geometric elements of the road and nodes, warning elements, road equipment elements, etc.

An important condition for road design is that the driver has the right to make mistakes, but the consequences of this mistake should be minimal.

Accordingly, the task of the designer from the point of view of safety is:

1. Provide comfortable driving conditions that exclude driver error;
2. In the event of a driver error, minimize its consequences.

Regulation of driver behavior on the road

The geometry of the road and the surrounding situation affect the speed of the vehicle. The wider the carriageway, the higher the selectable single vehicle speed. The straighter the road and the fewer turns, the higher the speed of the vehicle. Moreover, the driver often loses control of distance and speed. He always seems to be moving slowly.

On our roads, very often you can find long straight sections of roads connected by curves of small radius. On the one hand, this geometry allows the driver to develop the maximum speed for the car, on the other hand, the driver has to brake sharply before turning. A road sign warning of a turn may not be noticed by the driver.

Another negative factor of long straight sections is monotony, which leads to loss of attention and drowsiness.

According to the experience of road operation in Germany, it was revealed that, despite the profitability of straight lines in terms of the shortest distance between points, they are also the most dangerous elements of roads for drivers. For example, the most dangerous autobahn in Germany is the A2 Berlin-Hannover, which consists of long straight sections. On the basis of research in Germany, the standard for the maximum length of the straight section L = 20V calculated was adopted. That is, at an estimated speed of 120 km / h, the maximum length of the straight line will be 2400 m.

It is possible to reduce the maximum speed on the site by a variety of combinations of geometry and the surrounding situation. Smooth, consistent curves keep the driver from accelerating. And confined spaces, such as dense buildings or frequent plantings, also convey a sense of danger to the driver, and at high speeds in such conditions, the driver feels uncomfortable.

Compliance of geometric elements with the expectations of the driver

The geometric elements of roads and road junctions must meet the expectations of the driver. Driver expectations are in turn shaped by habits and previous elements. If the previous elements allowed to develop high speed, then it will be very dangerous to arrange a sharp turn after such elements. In order to smoothly reduce the speed of the driver, a sequence of elements with a gradual change in parameters is necessary. For example, it is not safe to insert a radius of 200 meters after a long straight section. However, if you insert several successive curves between the straight and small radius - with a radius of 2000, 1200, 800, 400 meters in decreasing order - then the driver himself will gradually reduce speed and will be safely prepared for a sharp turn.

Consider an example of junction at different levels of the Pipe type. VSN 103-74 states that, depending on local conditions and the traffic situation, a mirror scheme may be applied. The textbook "Intersections and junctions of highways" argues that one of the main determining factors for choosing a junction scheme of the type Pipe is the intensity of left-turn flows.

But in this case, the fact is missed that the driver moving down the left-turn exit to the adjoining road is already prepared for a small radius by the presence of a transitional speed lane, on which, out of habit, the speed decreases. And the driver entering on the left-turn exit from the adjoining road, as he was on the main road, remained on it, nothing but signs indicates to him that a small radius is approaching. Based on this argument, in Germany it is recommended to arrange a junction of the Pipe type with ramps on the left side of the overpass, since only in this case it is possible to use the maximum possible radii for this ramp with the highest level of security. In addition, it is necessary to indicate the presence of danger to the driver by the very geometry of the junction. The following figure shows a typical pipe interchange in Germany.

Despite all these conditions, in the latest German standards (2008) it is recommended, if possible, to consider options for a device of a safer type of junction - Triangle.

Conflict points

Conflict points are places of intersection, convergence and divergence of traffic flows. The most dangerous conflict points for transport interchanges are places of parallel crossing of traffic flows. They are related to the rebuilding of two parallel streams. At the same time, their trajectories intersect.

At high intensities, these conflict points not only affect traffic safety, but can also lead to the formation of congestion (see figure below). The driver needs to change lanes and at the same time monitor the situation in the adjacent lane, the intervals to vehicles in both lanes and the speed of vehicles in both lanes, as well as constantly check the blind zone. A particular problem in this case is slowly accelerating heavy-duty road trains, which are simply not allowed to change lanes by nimble cars, and which slow down the entire traffic flow.

It is possible to foresee this situation at the project stage by expert means, knowing the required traffic intensity. In Germany, such an assessment is carried out using a special methodology (to be covered in subsequent articles).

The cheapest improvement might be to lengthen the traffic lane by extending the left turn ramp along the main road. A more expensive solution is to install a direct or semi-direct left turn exit, which will completely avoid the area of ​​\u200b\u200bcrossing flows.

Various form improvements also serve to reduce the number of dangerous zones at interchanges. For example, the most convenient conditions for driving on the main road and in the area of ​​​​weaving streams are created when the exit on the main road is in front of the entrance. To do this, it is planned to separate the incoming and outgoing flows from the main road by a separate passage.

As a result, instead of two exits and two entrances, there is only one exit on the main course, followed by one entrance. Thus, the intersection area of ​​the flows is transferred from the main road to the exit and the total number of conflict points for the main traffic flow is reduced. The crossing of flows at the congresses occurs at lower speeds. This, in turn, increases the traffic interchange capacity and safety for drivers.

Almaty is one of the largest metropolises in Kazakhstan. Naturally, he, like other large cities in developed countries, is faced with the need to solve the problem of road junctions. Today, when designing roads, preference is given to modern technologies and methods of surveying, based primarily on the use of high-performance methods for collecting information about the area: the use of GIS technologies in surveying roads and structures on them, methods of ground and aerospace digital photogrammetry, satellite systems navigation "GPS", methods of electronic tacheometry, terrestrial laser scanning of the terrain and geophysical methods of engineering and geological surveys. Transport interchange is a complex of road structures (bridges, tunnels, roads) designed to minimize the intersection of traffic flows and, as a result, to increase the capacity of roads. Mostly, interchanges mean traffic intersections at different levels, but the term is also used for special cases of traffic intersections at the same level. To date, the construction uses the latest modern technologies in the construction of road interchanges to improve the quality and safety of interchanges.

In our city, devices such as the Leica TC 407 made in Switzerland are more often used, and they also produce various electronic roulettes and GPS systems.

The latest GIS programs such as Credo mix and AutoCAD are also used in the construction of interchanges. These programs are specially designed to solve problems in the construction of various types and complexity.

Types of road interchanges

Interchanges at the intersections and junctions of highways at different levels are the most complex road junctions in terms of designing a plan for connecting ramps, longitudinal and transverse profiles, vertical planning, and organization of surface drainage. Junctions at different levels, arranged primarily on highways of high categories, are designed to prevent the intersection of traffic flows of different directions at the same level with a corresponding increase in road capacity, traffic speeds, levels of convenience and traffic safety. On the example of a complex transport interchange, shown in Figure 1, their main elements are shown: intersecting highways, left-turn, right-turn ramps, directive left-turn ramps, overpasses.

The type and concepts of traffic interchanges are determined by many factors: the categories of intersecting roads, the prospective intensity of traffic flows in directions; relief and situational features of the terrain in the area of ​​intersection or junction, etc. Of the variety of developed schemes of traffic interchanges at intersections and junctions of highways, Figure 2 shows some of them that are used in the practice of transport construction.

Figure 1. Scheme of a complex traffic interchange at different levels:

1 - crossing highways; 2 - left turn ramps;

3 - right turn ramps; 4 - directive left turn ramps; 5 - viaducts

On the part of the current building codes and design rules, the following requirements are imposed on traffic interchanges:

Traffic interchange schemes at different levels on roads of categories I - II should not allow intersections of left-turn traffic with traffic flows of the main directions;

Crossings and junctions on roads of categories I - II are provided no more than after 5 km, and on roads of category III - no more than after 2 km;

Departures from roads of I - III categories and entrances to them are carried out with the device of transitional speed lanes;

Figure 2 - Schemes of traffic interchanges at intersections and junctions of highways at different levels:

a - cloverleaf interchange; b, c, d, e - combined clover-shaped interchanges with directive left-turn exits; e - interchange "compressed cloverleaf"; g - interchange "compressed incomplete cloverleaf"; h - diamond-shaped intersection; and - Adjacent to directive left-turn exits; l - Adjacent by the type of "pipe"; m - Adjacent with adjacent left-turn loops

On the sections of branches and junctions of exit ramps, traffic interchanges use special types of transition curves, characterized by parabolic or S-shaped laws of curvature change and best suited to the conditions of movement of vehicles with variable speeds along them. The width of the carriageway along the entire length of the left-turn exits is taken equal to 5.5 m, and on the right-turn exits - 5.0 m.

The width of the shoulders on the inside of the roundings at the exits should be at least 1.5 m, and on the outside - 3.0 m. The longitudinal slopes at the exits of traffic interchanges at different levels should not be more than 40.

One of the types of complex transport interchanges is clover-shaped. In the late 1960s, clover-shaped storage interchanges began to prevail over the classic clover-shaped ones abroad. With this design of the interchange, the ramps have become longer, and the turning radius has accordingly increased, which makes it possible to increase the speed of movement along it. In some cases, a third level interchange is used to lengthen short loop ramps.

The advantages of this interchange are that it is cheap compared to other types of interchange and only 2 levels are used for 2 highways, the exit is located before the entrance, the need to rebuild flows before exits from the highway is quantitatively reduced. High throughput interchange.

The disadvantages of decoupling are that one of the flows must predominate over the other. If the flows are compared, then it becomes impossible for public transport to pass through the traffic light zone, with an increase in flow, the tunnel may become clogged, a greater distance is needed before the next intersection.

Figure 3. Scheme of a clover junction

Another alternative to the four-level storage interchange is the turbine interchange (also called the Whirlpool, in translation - "swirl"). Typically, the turbine interchange requires fewer (usually two or three) levels, the interchange ramps spiraling towards its center. A special feature of the interchange is ramps with a large turning radius, which allow increasing the throughput of the interchange as a whole.

The advantage of this high capacity is that the exit is located before the entrance, as well as the need to change lanes before exits from the highway.

The disadvantages are that it requires a lot of space for construction, requires the construction of 11 bridges, sharp elevation changes on the overpasses of the congresses.

Figure 4. Decoupling scheme

Figure 5 - Interchange in kind (aerial photograph)

A traffic light interchange is formed by crossing two or more roads at an arbitrary angle (usually a right angle). The term "interchange" is used only when there is a complex traffic light cycle, the presence of other roads for turning traffic, or the prohibition of following in one of the directions.

Advantages:

2. Ability to allocate a separate cycle for pedestrians.

disadvantages

1. The problem of a left turn during heavy traffic on one of the roads;

2. With heavy traffic, the waiting time for green can be up to 10 minutes;

3. With heavy traffic, there is a high risk of traffic jams.

A traffic light with a pocket for a U-turn and a left turn is arranged in cases where there is already a division of flows on one of the streets.

Advantages:

1. Simplicity of traffic light cycles;

2. Used the available space at the old intersection.

Disadvantages:

1. Overloading the road, on which "pockets" are arranged, can create "traffic jams";

2. When turning left (and sometimes when turning), you must stand on at least two "reds" (to solve this problem, a right turn on red is usually allowed);

3. The situation for pedestrians worsens due to the reduction of the cycle or the elimination of the actual traffic light crossing. Such an interchange is often built along with an underpass;

4. It is necessary to remove obstacles to the visibility of pedestrians, or there is a danger of a right turn.

The roundabout in action is based on the fact that instead of an intersection, a circle is built, which can be entered and exited anywhere.

Advantages:

1. The number of traffic light cycles is reduced to a minimum of two (for a pedestrian crossing and the passage of cars), sometimes traffic lights are abolished altogether;

2. No left turn problem (when driving on the right);

3. Possible branch and more than four roads;

Disadvantages:

1. Cannot give priority to any (main) road; it is used, as a rule, on roads of similar congestion;

2. High emergency danger;

3. The need to clearly consider the flow of pedestrians;

4. Requires a lot of extra space;

5. Bandwidth is limited by the circumference;

6. No more than 3 traffic lanes.

Atypical solutions. K element. One of the roads necessarily consists of three segments, two of which are roads for movement each in its own direction, and the third is a dedicated lane, while at the intersection the central lane “changes” from one side. There are also special cases of leaving the selected lane to a secondary road with the allocation of a boulevard

Advantages:

1. The selected cycle for OT is combined with a left turn of two lanes;

2. The left turn passes with a drawn turn further through the central lane.

Disadvantages:

It is necessary to take into account the structure of the surrounding streets.

Types of interchanges for the intersection of the highway and the secondary road Parclo (Incomplete Deployment). An example of a "half-daisy" or partial clover.

Advantages:

1. More speed than typical clover due to longer stripes;

2. Cheaper due to the construction of shorter bridges;

3. All directions are involved;

4. Often designed specifically for the predominance of the left turn.

Disadvantages:

1. Only a part of the lanes for the exit / exit is allocated. It is not possible to select all bands;

2. U-turn from a secondary road is impossible in principle.

Traffic lights and tunnel. On the main road, a tunnel (or overpass) is being built for traffic straight ahead, for the rest, traffic lights are kept

Advantages

2. There are practically no obstacles to the movement of public transport;

3. It is often possible to make the upper zone predominantly pedestrian;

Disadvantages:

1. Predominance of one of the streams over the other is necessary. If the flows are compared, then the movement of public transport through the traffic light zone becomes impossible, with an increase in the flow, the tunnel may also become clogged;

2. A greater distance is needed before the next intersection compared to a traffic light;

Rhomboid junction with sideways change. Diverging diamond interchange.

One of the built variants in the USA.

A tunnel (or overpass) is built on the main road for direct traffic, while traffic lights are maintained for the second. Moreover, on a secondary road, the direction of traffic changes within the interchange.

Advantages:

1. Allows you to highlight the prevailing flow without compromising the secondary road;

2. Two phases for traffic lights instead of three in the classic diamond interchange;

3. Compared with the classic version of the diamond interchange, a large bandwidth;

4. Increased traffic safety by reducing the speed of movement on a secondary road and fewer conflict points;

5. There is a possibility of a U-turn for the main road.

Disadvantages:

1. Unusual traffic organization can greatly confuse drivers. Highly visible markings are required.

2. Can't work without traffic light regulation.

Ring with the selection of the direct direction.

An interchange differs from a roundabout in that the straight direction on the main road is marked off with a tunnel or overpass, and roundabouts are used for left turns and U-turns. Such interchanges are often built on the basis of roundabouts by highlighting the main road - this solution is often used in squares.

Compared to a conventional roundabout, such an interchange allows you to organize traffic without traffic lights in a straight line.

8. Fundamentals of the theory of designing a highway route (equation of vehicle movement).

9. Features of designing transition curves at transport interchanges.

10. Calculation schemes (formulas) for determining the visibility distances in the plan and profiles.

11. Basic principles of landscape design of roads.

12. Flatness of the carriageway - factors affecting the evenness and indicators "suffering" from evenness.

13. Rutting on coatings and methods for its prevention and elimination.

14. Composition of the road project, documents, level of detail.

15. Automated traffic control systems in modern conditions.

16. Local treatment facilities - types, designs, principles of operation.

17. Protection from traffic and technological noise in the area of ​​the highway route.

18. Meteorological provision of road safety.

1. Measures provided for in road projects

2. Activities carried out by the road service in the process of operation

19. Principles of road-climatic zoning (zoning) of the territory of the Russian Federation.

20. Modern systems for computer-aided design of roads: credo, robur.

21. Scope of work on engineering surveys for new construction and reconstruction of roads.

22. Modern geoinformation technologies used in road construction.

23. Features of engineering surveys at bridge crossings (scope of work, equipment, documents).

24. Measures to ensure the stability of the subgrade on unstable slopes (landslides, screes, landslides ...)

25. Vertical planning of urban areas, streets, intersections: methods, submitted documents.

27. Theoretical capacity of 1 lane.

28. Water-thermal regime of the subgrade - processes in the annual cycle.

29. Intersections and junctions of highways at the same level: planning decisions, traffic safety requirements.

30. Complexes for maintenance of traffic in modern conditions.

31. Features of subgrade structures in the 1st road-climatic zone. Ice on roads and in small artificial structures.

32. Production enterprises of road construction: quarries, abz, tsbz, bases of inert materials.

33. Methodology for determining the prospective traffic intensity when assigning a category of road (country and urban).

34. Types of pavement and types of pavement by solidity.

35. Appointment of the turn, the technique for designing the turn off.

37. Classification of pavement. Designing different types of clothes. Structural layers of pavement, their purpose.

38. Calculation of non-rigid type pavement for strength.

39. Calculation of pavement for frost resistance. Measures to ensure frost resistance.

40. Calculation of rigid pavement.

1. Calculation of pavement for frost resistance

2. Calculation of a concrete slab for strength

3. Calculation of thermal stresses in concrete slabs

41. Schemes of transport interchanges at different levels.

42. Designing ramps for right and left turns (standards and specifications).

43. Measures to ensure the stability of the subgrade.

44. Methodology of hydrological calculations for the appointment of the estimated flow in the design of bridge crossings.

45. Appointment of openings of large and medium bridges. Calculation of general and local erosion. Design of approaches to bridges and control structures.

46. ​​Appointment and functional role of geosynthetic materials in pavement structures, varieties and scope.

47. Characteristics of bitumen used in road construction. Methods for improving the properties of bitumen.

48. Asphalt concrete. Classification, properties, requirements, determination of physical and mechanical parameters, application in road construction. The use of shma, cast a / b. Compact asphalt.

49. Construction of foundations from soils reinforced with mineral and organic binders.

50. Technology of preparation of hot asphalt concrete.

51. The main methods of bitumen activation. Control and evaluation of the quality of asphalt mixtures.

52. Technological (operational) control and acceptance of asphalt concrete pavements. Tolerance requirements.

53. Methods for improving the productivity of earth-moving machines.

54. Organization and technology of excavation of soils by excavators.

55. Features of traffic on urban roads, their design differences from automobile (country) roads.

56. Natural stone materials and industrial waste, directions, and justification for the expediency of their use in road construction.

57. Prefabricated road surfaces, modern design solutions and laying technology.

58. Technology for the manufacture of concrete products at reinforced concrete factories.

59. Composition and development of a business plan for a construction organization.

60. Methods of organizing road construction. Optimization of work organization models.

61. Technologies for the construction of subgrade in swamps.

62. Methods for assessing the transport and operational condition of highways and urban roads.

63. Methods of organizing traffic.

64. Technical means of organizing traffic.

65. Methods for assessing and predicting the service life of non-rigid pavements based on risk theory.

66. Ways to deal with winter slipperiness and snow in the maintenance of highways and urban roads.

67. Basic requirements for the transport and operational performance of road surfaces.

68. Methods for assessing the strength of pavements. The main types and causes of deformation and destruction of pavement.

69. Influence of technological factors of road construction and traffic on the natural environment.

70. Fundamentals of the theory and methods of soil compaction, control during compaction.

3.Cutting ring method

4. Density-hygrometer Kovalev

71. Installation of paved mosaic, clinker and block bridges, constructive solutions and technology.

72. Guidelines, norms and rules for environmental protection.

73. Methods of traffic control on highways and urban roads in modern conditions.

74. Automatic regulation of traffic on the highways of the city.

75. Ways to increase the roughness, adhesion qualities of a/b coatings.

76. Classification of work in the reconstruction and repair of roads.

77. Capacity of existing roads and measures to increase it.

78. Ways to widen the subgrade during the reconstruction of roads.

79. Reconstruction of pavement. Regeneration of asphalt concrete pavements. Features of technology and organization of work in the reconstruction of roads.

80. Theoretical foundations of moisture accumulation in subgrade and pavement.

81. Methods and models of organizing the construction of roads.

82. Principles, methods, systems, functions and structures of road construction management.

83. Production cost effectiveness calculations, present value.

84. Quality management. International ISO 9000 series quality standards. Quality improvement efficiency.

85. Quality control (types, methods, means), quality assessment.

87. Designs and technology of cement concrete pavement. Construction of prestressed coatings.

86. Technical regulation and standards in the road sector; methods of technical regulation, methodology for developing production standards.

88. The device of coatings from polymer concrete and concrete polymers.

INTERSECTIONS

1) Clover leaf (Fig. 1) - the most widely used scheme. Note when crossing 2 highways between themselves or when crossing highways with roads of lower categories. Advantages:

Possibility of designing right-handed exits with curves of a larger radius with small longitudinal slopes, which allows to increase the speed of movement; - There is only one overpass.

2) Incomplete cloverleaf application: - when individual swerving flows have low intensity => designing independent ramps is not economical; - in order to save land acquisition near the settlement; - when the road has an obstacle. Disadvantage: the presence of intersection points in the same level, rounding of small radii, requiring a significant reduction in speeds.

a) with 4 single-track exits (Fig. 2); b) with 2 double-track exits located in neighboring quarters (Fig. 3); in) with 2 double-track, located in the adjacent quarters (Fig. 4).

1. 2.

3.
4.

5. 6.7.8.

distribution ring a) from the 5th overpass. (Fig.5). To accommodate ascents and descents, a large radius of the ring is required, which requires a large area of ​​land acquisition. Left-handed cars make a big overrun. Has a simple configuration, easy to navigate; b) with 2 overpasses. Fewer overpasses => lower construction cost; in) improved type of ring. Complex configuration, not economical; G) turbine type of crossing. Not economical

a) diamond type. Sozhnaya construction (9 overpasses); b) curvilinear triangle (16 viaducts); in) H-shaped type (9 overpasses).

All have high cost builds.

CONNECTIONS

TR based on cloverleaf elements:

a) by the type of "pipe" (Fig. 6). The basic scheme for connecting a secondary road to the main road is compact and does not require. alienation of a large area of ​​land. No crossing points in one level, simple configuration.; b) leaf-shaped type (Fig. 7). more safety, no mixing of different turning flows, simple configuration; in) by the type of incomplete clover leaf;

TR based on ring elements:

a) ring type (Fig. 8); b) pear-shaped; in) mushroom-shaped

TR with parallel arrangement of right turn and left turn ramps:

a) T-type; b) like a triangle

42. Designing ramps for right and left turns (standards and specifications).

Right-turn exit - movement on it is carried out by turning to the right.

Left turn exit:

1) indirect ("cloverleaf")

2) half-line (first turn to the right, then to the left);

Right-turn exits at interchanges are made in the form of a combination of transition curves, as well as straight inserts. Left-turn exits, as a rule, are closer in shape to a circle. The radii of the curves are determined from the condition of ensuring the design speed at the ramps. For right-handers it is 60 km/h (for category III) and 80 km/h (for categories I and II), the corresponding minimum radii are 125 and 250 m. For left-handers it is 40 km/h (for category III). .) and 50 km/h (for I and II cat.), corresponding lines with radii of 50 and 80 m.

The values ​​of the transverse slope of the turns at the exits in areas with rare cases of ice formation are taken equal to:

For loops of left-turn ramps of “cloverleaf” intersections 60% o;

For right-turn exits, calculated at a speed of 60-90 km / h, 30% o, at a speed of 40-50 km / h - 60% o;

For straight, semi-direct and circular left-turn exits 30% o;

For other types of exits, calculated at a speed of 40-50 km / h, 60% o.

The transverse slope on the roadsides of the ramps, reinforced with stone materials, is 50 (60% o, with asphalt concrete roadsides 30-40% o.

The width of the carriageway at one-lane exits of interchanges is:

for loops of left-turn ramps of interchanges of the “cloverleaf” type 5.5 m;

For right-turn exits, calculated at a speed of 60-90 km / h, 5 m, at a speed of 40-50 km / h - 4.5 m;

For straight and semi-straight left-turn exits with a radius of more than 100 m - 5.0 m.

The width of the shoulders on the inside of the curves is 1.5 m, on the outside - 3.0 m.

When arranging congresses with several lanes, the width of the carriageway is assigned based on the recommendations for determining the width of lanes on the roundings of highways.

For more confident driving and better visual perception by the driver of the lane edges on the carriageway of exits, it is advisable to arrange edge strips that differ in color from the main coating, 0.5 m wide for speeds of 40 (50 km/h and 0.75 m for higher movement speeds.

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