Turbine roundabouts: no traffic jams! Transport interchanges T-shaped interchange.

The term is more often used in relation to complexes for one specific type of transport. In Russia, the most famous are road junctions located in Moscow (MKAD, Garden Ring, Third Transport Ring, etc.), as well as railway junctions. Terms Types of traffic light junctions Traffic light It is formed by the intersection of two or more roads at an arbitrary angle (usually right). The term “interchange” is used only when there is a complex traffic light cycle, there are other roads for turning traffic, or traffic in one of the directions is prohibited. Advantages Simplicity of traffic light cycles Possibility to allocate a separate cycle for pedestrians Flaws Problem with left turn during heavy traffic on one of the roads In heavy traffic, the waiting time for a green light can reach 10 minutes (For example, earlier on Kudrinskaya Square) When there is a lot of traffic, there is a high risk of traffic jams Traffic light with a pocket for turning and left turning Such an interchange is arranged in cases where there is already a separation of flows on one of the streets. Advantages Simplicity of traffic light cycles. The existing space at the old intersection is used. Flaws Overloading the road where the “pockets” are located can create “traffic jams”. For example, in the area of ​​the final station “Profsoyuznaya”, after disembarking, public transport does not have time to immediately change into 3 rows, which leads to confusion When making a left turn (and sometimes when making a U-turn), you must stand on at least two red lights (to solve this problem, right turns on red are usually allowed). The situation for pedestrians is worsening due to the shortening of the cycle or the elimination of a virtually traffic-light-free crossing. Such an interchange is often built together with an underground passage. It is necessary to remove obstacles to the visibility of pedestrians, or there is a danger of making a right turn. Circular It is based on the fact that instead of an intersection, a circle is built into which you can enter and exit anywhere. Advantages The number of traffic light cycles is reduced to a minimum of two (for pedestrian crossings and vehicles), sometimes traffic lights are abolished altogether No left turn problem (when driving on the right) A branch of more than four roads is possible Flaws Cannot give priority to any (main) road; It is usually used on roads of similar congestion. High emergency hazard The need to clearly take into account pedestrian flows Requires a lot of extra space Capacity limited by circumference No more than 3 lanes Atypical solutions K-element One of the roads necessarily consists of three segments, two of which are roads for traffic each in its own direction, and the third is a dedicated lane, while at the intersection the central lane “changes” with one side. There are also special cases of a dedicated lane going onto a secondary road (Vavilov Street) with the allocation of a boulevard (Nakhimovsky Prospekt). Advantages: The dedicated cycle for OT is combined with a left turn of two lanes. The left turn extends with a pulled turn further through the center lane. Flaws: It is necessary to take into account the structure of the surrounding streets. Types of junctions for crossing a highway and a secondary road Parclo (Parclo deployment) Or partial clover. Popular in Moscow. Thus, the most striking example is the interchanges at the Kuntsevskaya metro station or at the entrance to Reutov/Ivanovskoye. Advantages More speed than a typical clover due to longer stripes Cheaper due to the construction of shorter bridges All directions are involved Often designed specifically for the predominance of left turns Flaws: Only part of the exit/exit lanes is allocated. It is impossible to select all stripes. Turning around from a secondary road is impossible in principle. Traffic light-tunnel overpass), traffic lights remain for the rest Advantages There are practically no obstacles to public transport It is often possible to make the upper zone predominantly pedestrian (example: Triumphal Square in Moscow) Flaws Predominance of one of the flows over the other is necessary. If the flows are compared, then it becomes impossible for public transport to move through the traffic light zone (for example, on Mosfilmovskaya Street), and as the flow increases, the tunnel may become clogged A greater distance is required before the next intersection compared to a traffic light Diamond-shaped interchange with change of side A tunnel (or overpass) is built directly on the main road for traffic, while traffic lights remain on the second road. Moreover, on the secondary road the direction of traffic within the interchange changes. Advantages Allows you to highlight the dominant flow without damaging the secondary road Two phases for traffic lights instead of three in a classic diamond interchange Compared to the classic version of a diamond-shaped interchange, greater throughput Increased traffic safety due to reduced speed on secondary roads and fewer conflict points There is a possibility of turning around for the main road Flaws Unusual traffic arrangements can greatly confuse drivers. Clearly visible markings are required. Cannot work without traffic light control Circular with forward direction highlighted Cumulative Cumulative, or stack (stack interchange) - an interchange in which part of the lanes is allocated from one road and merged into another road in the same quantity. The simplest version is on diamond-shaped roads extending to the right, from which left-turn roads extend directly from the center. It may also have a more complex design. Complex junctions are often called "Spaghetti" or "Maltese Cross" Advantages There are no hostile flows, flow formation occurs before decoupling Can be used at any intersection of any number of roads; 9-level [ ] The ability to select roads for turning at a greater distance compared to clover-shaped ones. Flaws Complex design, high cost of construction: in addition to the direct intersection, it is necessary to build curved overpasses for left turns (for a four-level one - 4) Clover accumulative In the late 1960s, clover-shaped accumulative interchanges began to prevail over classic clover-shaped interchanges abroad. This type of interchange is a natural evolution of the classic clover, when instead of a pair of clover exits, which are blocked due to the problem of cars leaving and entering the interchange during heavy traffic (flow conflict), separate exits are built. With this design, when moving along any of the intersecting highways, there is first a vehicle exit from the main highway, allowing everyone to leave the highway, and only then does the vehicle enter from the intersecting highway. With this design of the interchange, the exits have become longer, and the turning radius has accordingly increased, which ultimately makes it possible to increase the speed of movement along it. In some cases, a third level of interchange is used to lengthen short loop ramps. Advantages Cheaper than the storage interchange, only 2 levels are used for 2 highways. High interchange capacity. Convenient to convert from clover-shaped. Flaws Seven bridges need to be built. Turbine decoupling An alternative to a four-level storage decoupler is a turbine decoupler (also called a “turbine decoupler”). Vepul ", translated as "swirl"). Typically, a turbine interchange requires fewer levels (usually two or three), with the interchange's ramps spiraling toward its center. A special feature of the interchange is ramps with a large turning radius, which increase the throughput of the interchange as a whole. Advantages: High throughput. The exit is located before the entrance. The need to change lanes before exiting the highway is quantitatively reduced. Flaws: Requires a lot of space for construction. Requires the construction of 11 overpasses. Sudden changes in elevation on ramp ramps. Additional turning roads are needed. Mill screw type decoupler Another alternative to the four-level cumulative decoupling is the mill screw type decoupling. It is one of the options for turbine decoupling. A distinctive feature of such interchanges is the need for only 2 levels and the construction of only five bridges. At the same time, in the version of the windmill-type cross interchange, the throughput of the interchange increases due to the crossing of highway flows (in the case of right-hand traffic at the interchange, it becomes left-hand traffic). In addition, turns become more understandable from the point of view of a traffic participant; they are more clearly highlighted. The interchange received its name for its characteristic ramps, similar to the propeller of a windmill. Advantages High throughput The exit is located before the entrance Requires the construction of only five bridges Possibility of organizing turns for mill blade crossovers Flaws The turns have a smaller radius compared to turbine and storage interchanges. Additional turning roads needed Roundabout with two straight paths Advantages: Compactness A simple turn around the ring Possibility of changing from a roundabout Flaws: The speed of movement on the ring is limited by its size Conflicting threads on the ring can lead to congestion Diamond-shaped On the approaches to the junction, the roads branch into right and left turns; the intersection of streams is separated by a bridge. Inside the diamond formed by the left turn roads, a straight intersection is built as a branch from them; in this case, the directions of movement change (right-hand becomes left-hand). Advantages: High throughput and speed of movement; Left turns have the same large radius as right turns; There are no warring flows (entry after exit); Left turns are intuitive. Flaws: Construction of 5 bridges is required; In the basic configuration, turning is not possible. Types of traffic-lightless junctions for connecting highways Tubular Two-level interchange, one of the left turns is made as a right turn at 270 degrees. Rotation is not possible in the basic configuration. During construction, the interchange requires the construction of only one direct intersection. This interchange is most popular, in particular, on the Moscow Ring Road. T-shape At a T-junction, left turns are made at individual levels using overpasses or tunnels. Compared to the tube-shaped one, the turns are smoother; there is no 270-degree turn, which is convenient for high-speed traffic. However, the need to construct two curved overpasses for left turns makes construction more complicated and expensive. Rotation is not possible in the basic configuration. Y-shaped In a Y-interchange, opposing directions of traffic are separated by a distance, after which roads are diverted from the direct directions for left turns. Compared to a T-junction, left turns require the construction of three short overpasses. Semi-clover A two-level interchange in which both left turns are made as right turns at 270 degrees. In the basic configuration, a U-turn on an adjacent road is possible. There may be inherent flow conflict in the clover interchange due to the location of the entrance before the exit. During construction, the interchange requires the construction of only one direct intersection; when extending the road, it is possible to expand to a clover intersection. Promising interchange projects Turbine-ring transport interchanges of Shulyakin in nine options, there are five more options for transport interchanges that are not patented [ ] and three options for Star Square in Paris [ ], where 12 roads converge. Flaws: Average design complexity. Sudden changes in altitude, but no more than 10 degrees. Not for central city intersections.

Traffic jams are the bane of any modern metropolis. In order to save city residents time and distribute traffic flows, design engineers sometimes resort to amazing solutions, which we will talk about in our material.

Judge Harry Pregerson Roundabout, Los Angeles

One of the world's most intricate road structures, combining passenger transport routes, the Harbor Transit Road and the Los Angeles Metro Green Line, opened in 1993. This tricky tangle of roads, located at the intersection of I-105, which leads from El Segundo to Norwalk, and I-110, which goes from San Pedro to Los Angeles, bears the name of federal judge Harry Pregerson for a reason. Like the famous lawman who managed to navigate the jungle of the legal dispute over the construction of I-105, the highway interchange masterfully resolves endless traffic flows. In just one day, this labyrinth, which allows you to turn in any direction on all sections of the route, crosses more than 500 thousand cars. There is only one problem - if you miss that one right turn, and the miracle of engineering will turn into an endless Mobius strip for you.

Cycle roundabout, Eindhoven

State support for cyclists, deployed in Holland, has led to amazing results: in recent years, the majority of the country's population prefers to use environmentally friendly and economical two-wheeled transport at home. For the convenience of those who chose to give up cars, special infrastructure began to be created - for example, the unique road junction The Honvering in Eindhoven. Suspended over a busy transport hub, this circular steel bridge allows traffic to be bypassed. The amazing structure is supported on a central 70-meter pillar using metal cables, and for reliability it is also reinforced with concrete columns. The creators of The Hovering claim that the future lies with such technologies, eliminating traffic accidents and decorating landscapes with unusual futuristic designs.

Gravelly Hill Interchange, Birmingham

The construction of a tangled, thread-like road junction in Birmingham took four years. Many technological problems and engineering snags stood in the way of the designers, who were forced to combine two railway lines and 18 road routes into one network, from the A38 state road leading from Cornwall to Northampshire to narrow country roads without a name, and link it all across three canals and two rivers. To ensure better throughput and good stability, the builders were forced to re-lay almost 22 kilometers of road surface and install 59 columns, placing the highway at five levels of different heights. With the light hand of a local newspaper reporter, the result of hard work, which appeared to the world in May 1972, received the playful nickname “Spaghetti Denouement.” This frightening design is painfully reminiscent of “a mixture of a plate of pasta and an unsuccessful attempt to tie a Staffordshire knot.”

Transport interchange on Taganskaya Square, Moscow

Even those who know the “rules of the game” and have been moving along the Tagansky streets and alleys for a long time often get lost on the Garden Ring. What can we say about those who first found themselves at the intersection of the busiest roads in Moscow, located in the heart of the Central District of the capital. Where the Bolshoi Krasnokholmsky Bridge connects with Zemlyanoy Val Street, chaos always reigns. Several highways leading from Nizhnyaya and Verkhnyaya Radishchevsky, Goncharnaya, Marxistskaya, Vorontsovskaya, Taganskaya, Narodnaya streets and numbering six or more lanes are teeming with endless rows of cars. The incessant noise of passing traffic is cut through by sharp signals, and traffic jams during rush hours have no end in sight. The colorful picture of one of the worst road junctions in the world is completed by two Moscow metro stations, a bus stop and an almost complete absence of signs.

Interchange at Place Charles de Gaulle, Paris

The brilliant French city planners who gave Paris the Square of the Star probably did not have the gift of foresight. Over the past centuries, the “patch” near the famous Arc de Triomphe, lively even by the standards of the 19th century, has turned into a real hell for motorists. Despite the fact that from the central city parade ground, like the rays of a star, 12 straight and wide avenues diverge in different directions, and several metro lines, RER, bus routes and highways converge, there are no traffic lights or priority signs. It’s no wonder that even Parisian taxi drivers, who drive around the area a hundred times a day, sigh sadly when they receive an order for Charles de Gaulle Square. Neither intuition, nor good knowledge of traffic rules, nor many years of driving experience can save you from the horror that happens here during rush hour: at the interchange, which is ranked as the most difficult route in the world, several accidents happen per hour.

Transport interchange- a complex of road structures (bridges, tunnels, roads), designed to minimize intersections of traffic flows and, as a result, to increase road capacity. Transport interchanges primarily refer to transport intersections at different levels, but the term is also used for special cases of transport intersections at one level.

The term is more often used in relation to complexes for one specific type of transport. In Russia, the most famous are road junctions located in Moscow (MKAD, Garden Ring, Third Transport Ring, etc.), as well as railway junctions.

Terms

The article uses terms for right-hand traffic; in the case of left-handed, the principle remains the same, only you need to replace left/right. This does not exclude areas with traffic in the other direction, as on Zvezdny Boulevard.

Types of traffic light junctions

Traffic light

It is formed by the intersection of two or more roads at an arbitrary angle (usually right). The term “interchange” is used only when there is a complex traffic light cycle, there are other roads for turning traffic, or traffic in one of the directions is prohibited.

Advantages

1. Simplicity of traffic light cycles
2. Possibility to allocate a separate cycle for pedestrians

Flaws

1. Problem with left turn during heavy traffic on one of the roads
2. In heavy traffic, the waiting time for a green light can reach 10 minutes (For example, earlier on Kudrinskaya Square)
3. When there is a lot of traffic, there is a high risk of traffic jams

Traffic light with a pocket for turning and left turning

Such an interchange is arranged in cases where there is already a separation of flows on one of the streets.

Advantages

1. Simplicity of traffic light cycles.
2. The existing space at the old intersection is used.

Flaws

1. Overloading the road where the “pockets” are located can create “traffic jams”. For example, in the area of ​​the final station “Profsoyuznaya”, after disembarking, public transport does not have time to immediately change into 3 rows, which leads to confusion
2. When making a left turn (and sometimes when making a U-turn), you must stand on at least two red lights (to solve this problem, right turns on red are usually allowed).
3. The situation for pedestrians is worsening due to the shortening of the cycle or the elimination of a virtually traffic-light-free crossing. Such an interchange is often built together with an underground passage.
4. It is necessary to remove obstacles to the visibility of pedestrians, or there is a danger of making a right turn.

Circular

It is based on the fact that instead of an intersection, a circle is built into which you can enter and exit anywhere.

Advantages

1. The number of traffic light cycles is reduced to a minimum of two (for pedestrian crossings and vehicles), sometimes traffic lights are abolished altogether
2. No left turn problem (when driving on the right)
3. A branch of more than four roads is possible

Flaws

1. Cannot give priority to any (main) road; It is usually used on roads of similar congestion.
2. High emergency hazard
3. The need to clearly take into account pedestrian flows
4. Requires a lot of extra space
5. Capacity limited by circumference
6. No more than 3 lanes

Atypical solutions

K-element

One of the roads necessarily consists of three segments, two of which are roads for traffic each in its own direction, and the third is a dedicated lane, while at the intersection the central lane “changes” with one side. There are also special cases of a dedicated lane going onto a secondary road (Vavilov Street) with the allocation of a boulevard (Nakhimovsky Prospekt).

Advantages:

1. The dedicated cycle for OT is combined with a left turn of two lanes.
2. The left turn extends with a pulled turn further through the center lane.

Flaws:

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

Types of junctions for crossing a highway and a secondary road

Parclo (Parclo deployment)

Or partial clover. Popular in Moscow. Thus, the most striking example is the interchanges at the Kuntsevskaya metro station or at the entrance to Reutov/Ivanovskoye.

Advantages

1. More speed than a 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 left turns

Flaws:

1. Only part of the exit/exit lanes is allocated. It is impossible to select all stripes.
2. Turning around from a secondary road is impossible in principle.

Traffic light-tunnel

overpass), traffic lights remain for the rest

Advantages

1. There are practically no obstacles to public transport
2. It is often possible to make the upper zone predominantly pedestrian (example: Triumfalnaya Square in Moscow)

Flaws

1. Predominance of one of the flows over the other is necessary. If the flows are compared, then it becomes impossible for public transport to move through the traffic light zone (for example, on Mosfilmovskaya Street), and as the flow increases, the tunnel may become clogged
2. A greater distance is required before the next intersection compared to a traffic light

Diamond-shaped interchange with change of side

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

Advantages

1. Allows you to highlight the dominant flow without damaging the secondary road
2. Two phases for traffic lights instead of three in a classic diamond interchange
3. Compared to the classic version of a diamond-shaped interchange, greater throughput
4. Increased traffic safety due to reduced speed on secondary roads and fewer conflict points
5. There is a possibility of turning around for the main road

Flaws

1. Unusual traffic arrangements can greatly confuse drivers. Clearly visible markings are required.
2. Cannot work without traffic light control

Circular with forward direction highlighted

Cumulative

Cumulative, or stack (stack interchange) - an interchange in which part of the lanes is allocated from one road and merged into another road in the same quantity.

The simplest version is on diamond-shaped roads extending to the right, from which left-turn roads extend directly from the center. It may also have a more complex design. Complex junctions are often called "Spaghetti" or "Maltese Cross"

Advantages

1. There are no hostile flows, flow formation occurs before decoupling
2. Can be used at any intersection of any number of roads; 9-level [ ]
3. The ability to select roads for turning at a greater distance compared to clover-shaped ones.

Flaws

1. Complex design, high cost of construction: in addition to the direct intersection, it is necessary to build curved overpasses for left turns (for a four-level one - 4)

Clover accumulative

In the late 1960s, clover-shaped accumulative interchanges began to prevail over classic clover-shaped interchanges abroad. This type of interchange is a natural evolution of the classic clover, when instead of a pair of clover exits, which are blocked due to the problem of cars leaving and entering the interchange during heavy traffic (flow conflict), separate exits are built. With this design, when moving along any of the intersecting highways, there is first a vehicle exit from the main highway, allowing everyone to leave the highway, and only then does the vehicle enter from the intersecting highway.

With this design of the interchange, the exits have become longer, and the turning radius has accordingly increased, which ultimately makes it possible to increase the speed of movement along it. In some cases, a third level of interchange is used to lengthen short loop ramps.

Advantages

1. Cheaper than a storage interchange, only 2 levels are used for 2 highways
2. The exit is located before the entrance
3. interchanges
4. Convenient to convert from clover-shaped

Flaws

1. Additional turning roads needed
2. Seven bridges need to be built

Turbine decoupling

Another alternative to a four-level storage interchange is a turbine interchange (also called a “turbine interchange”). Whirlpool ", translated as "swirl"). Typically, a turbine interchange requires fewer levels (usually two or three), with the interchange's ramps spiraling toward its center. A special feature of the interchange is ramps with a large turning radius, which increase the throughput of the interchange as a whole.

Advantages

1. High throughput
2. The exit is located before the entrance
3. The need to change traffic lanes before exiting the highway is quantitatively reduced

Flaws

1. Requires a lot of space for construction
2. Requires the construction of 11 overpasses
3. Sudden changes in elevation on ramp ramps
4. Additional turning roads needed

Mill screw type decoupler

Another alternative to the four-level cumulative decoupling is the mill screw type decoupling.

It is one of the options for turbine decoupling. A distinctive feature of such interchanges is the need for only 2 levels and the construction of only five bridges.

At the same time, in the version of the windmill-type cross interchange, the throughput of the interchange increases due to the crossing of highway flows (in the case of right-hand traffic at the interchange, it becomes left-hand traffic). In addition, turns become more understandable from the point of view of a traffic participant; they are more clearly highlighted.

The interchange received its name for its characteristic ramps, similar to the propeller of a windmill.

Advantages

1. High throughput
2. The exit is located before the entrance
3. Requires the construction of only five bridges
4. Possibility of organizing turns for mill blade crossovers

Flaws

1. The turns have a smaller radius compared to turbine and storage interchanges.
2. Additional turning roads needed

Roundabout with two straight paths

Advantages:

1. Compactness
2. A simple turn around the ring
3. Possibility of changing from a roundabout

Flaws:

1. The speed of movement on the ring is limited by its size
2. Conflicting threads on the ring can lead to congestion

Diamond-shaped

On the approaches to the junction, the roads branch into right and left turns; the intersection of streams is separated by a bridge. Inside the diamond formed by the left turn roads, a straight intersection is built as a branch from them; in this case, the directions of movement change (right-hand becomes left-hand).

Advantages:

1. High throughput and speed of movement;
2. Left turns have the same large radius as right turns;
3. There are no warring flows (entry after exit);
4. Left turns are intuitive.

Flaws:

1. Construction of 5 bridges is required;
2. In the basic configuration, turning is not possible.

Types of traffic-lightless junctions for connecting highways

Y-shaped

In a Y-interchange, opposing directions of traffic are separated by a distance, after which roads are diverted from the direct directions for left turns. Compared to a T-junction, left turns require the construction of three short overpasses.

Semi-clover

A two-level interchange in which both left turns are made as right turns at 270 degrees. In the basic configuration, a U-turn on an adjacent road is possible. There may be inherent flow conflict in the clover interchange due to the location of the entrance before the exit. During construction, the interchange requires the construction of only one direct intersection; when extending the road, it is possible to expand to a clover intersection.

Source not specified 1299 days ], where 12 roads converge.

Advantages:

Flaws:

1. Average design complexity.
2. Sudden changes in altitude, but no more than 10 degrees.
3. Not for central city intersections.

Roundabouts, popular in various countries, particularly the UK, are clearly more efficient than full-stop or other types of intersections. But in many places, including the US, they have not found acceptance.

Several explanations can be given for this. Some experts point to historical differences in the evolution of infrastructure and government investment, while others argue that the British culture of teamwork is incompatible with the American mentality. Or, perhaps, the Americans once looked at this junction and rushed off into the night with screams of horror.

Swindon, England, is home to perhaps one of the most bizarre-looking intersections ever created by man: the world's first "Magic Roundabout," also known as a "roundabout."

The complex interchange consists of five smaller, separate roundabouts that direct traffic clockwise and are arranged around one central ring that runs counterclockwise.



Motion diagram

Despite its scary appearance, this configuration is much more effective than conventional roundabouts and has been adopted for implementation in other parts of Britain.

Each of the outer circles serves the entry and exit of vehicles from the corresponding road. Experienced drivers can navigate the interchange in a more efficient manner and save time. Less experienced people can go with the flow, driving around the edges until they reach the desired exit. For drivers traveling from one end of the interchange to the opposite end, the Magic Roundabout can take half the time to cross than a standard roundabout.

Traffic congestion in Swindon has been greatly reduced by the design of this junction, even as traffic gradually increases. But the subjective opinions of drivers unfamiliar with it may differ from each other.

The interchange was designed by engineer Frank Blackmore, who worked at the British Transport and Road Research Laboratory. The now famous Swindon roundabout dates back to 1972. It was originally called the County Islands, but was quickly dubbed the "Magic Roundabout" and as a result the name became official.

Blackmore developed the design by comparing single roundabouts with straight-line alternatives, and then began adding double, triple and quadruple options:

At first, there were traffic policemen stationed at the junction all the time, called upon to help drivers. A successful experiment led to their replacement with road signs.

But the Magic Roundabout has its critics. A British insurance company named it the worst in the world, it received the same epithet from one of the car magazines, and it was also included in the top ten worst endings in a BBC News poll.

Despite some negative press, Swindon Interchange has a surprisingly excellent record of safety and efficiency. A very complex type of interchange hides a rather simple set of rules for driver behavior:

1. Avoid collisions;
2. Follow the lines and arrows;
3. Give way to people already at the junction;
4. Follow to your goal.

Tom Scott, the producer of the following video, compares the appearance of chaos at a roundabout to the complex behavior of groups of birds. As he notes in the video, even a few simple rules can lead to what to an outside observer looks like chaotic behavior in flocks of birds.

The key property of decoupling is the simplicity of the rules. Efficiency is achieved by reducing traffic speed and increasing driver attention. At uncontrolled intersections, both roundabouts and regular ones, drivers tend to pay more attention to the road and their surroundings based on their own judgment rather than on signals and signs.

There are even people advocating for an extreme extension of this principle, for a “shared space” free of traffic lights, signs, sidewalks and markings. This type of traffic control is not as comfortable, but the attentiveness it generates forces drivers to keep an eye on the road, bicycles and pedestrians as well as the road ahead.

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Topic: “Forwarding operations when sending cargo”

1. Basic concepts and definitions

Transport interchange- connecting highways at different levels with exits for the passage of cars and other vehicles from one road to another. Transport interchanges are arranged on roads of the 1st, 2nd, 3rd categories.

Depending on the relative position of roads, traffic intersections are divided into 3 groups: intersections, junctions, and branches. According to the method of carrying out left-turn traffic, traffic intersections are distinguished, at which it is made by turning to the right (Fig. 1, a), left (Fig. 1, b), left and right (Fig. 1, c).

Transport interchanges improve road capacity, safety, smoothness and speed of traffic compared to at-grade intersections.

Transport interchanges are designed based on a study of traffic flows in all directions, taking into account the landscape and free space. In this case, modeling of transport interchanges is often used.

The estimated speed is 40-80 km/h. The type of transport interchanges is selected as a result of a technical and economic comparison of options. Cloverleaf-type intersections are most widely used in Russia and abroad, for example, on the Moscow Ring Road.

The development of transport interchanges is associated with further improvement of traffic patterns.

There are interchanges:

Type A junctions, the connecting roads of which avoid any intersection of traffic flows.

Type B junctions ensuring the absence of intersections between the carriageways of motorways.

Type B junctions ensure that there is no intersection of the carriageway(s) of the expressway.

At intersections of secondary importance, where for economic reasons the construction of an interchange is impractical, intersections are provided at the same level or at different levels, regulated, if possible, by traffic lights.

Rice. 1. Schemes of transport interchanges.

2 . In andy interchanges

Types of traffic light junctions

Traffic light

It is formed by the intersection of two or more roads at an arbitrary angle (usually right). The term “interchange” is used only when there is a complex traffic light cycle, there are other roads for turning traffic, or traffic in one of the directions is prohibited.

Advantages

1. Simplicity of traffic light cycles

2. Possibility to allocate a separate cycle for pedestrians

Flaws

1. The problem of turning left during heavy traffic on one of the roads

2. In heavy traffic, the waiting time for a green light can reach 10 minutes (For example, earlier on Kudrinskaya Square)

Traffic light with a pocket for turning and left turning

Such an interchange is arranged in cases where there is already a separation of flows on one of the streets.

Advantages

1. Simplicity of traffic light cycles.

2. The existing space at the old intersection is used.

Flaws

1. Overloading the road where the “pockets” are located can create “traffic jams”. For example, in the area of ​​the Profsoyuznaya terminal station, after disembarking, public transport does not have time to immediately change into 3 rows, which leads to confusion

2. When making a left turn (and sometimes when making a U-turn), you must stand on at least two red lights (to solve this problem, right turns on red are usually allowed).

3. The situation for pedestrians is worsening due to the shortening of the cycle or the elimination of a virtually traffic-light-free crossing. Such an interchange is often built together with an underground passage.

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

Circular

It is based on the fact that instead of an intersection, a circle is built into which you can enter and exit anywhere.

Advantages

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

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

3. A branch of more than four roads is possible

Flaws

1. Cannot give priority to any (main) road; It is usually used on roads of similar congestion.

2. High emergency hazard

3. The need to clearly take into account pedestrian flows

4. Requires a lot of extra space

5. Capacity is limited by the circumference

6. No more than 3 lanes

Traffic light-tunnel

One of the options

A tunnel (or overpass) is built directly on the main road for traffic; traffic lights remain for the rest

Advantages

1. Allows you to highlight the dominant flow without damaging the secondary road

2. There are practically no obstacles to public transport

3. It is often possible to make the upper zone predominantly pedestrian (example: Triumfalnaya Square in Moscow)

DisadvantageAnd

1. Predominance of one of the flows over the other is necessary. If the flows are compared, then it becomes impossible for public transport to move through the traffic light zone (for example, on Mosfilmovskaya Street), and as the flow increases, the tunnel may become clogged

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

Types of traffic-lightless interchanges for two intersecting highways

Clover-shaped

Typical

Advantages

1. Not much space is required (compared to other types of multi-level interchanges).

2. It is possible to turn around in the basic configuration, although it is difficult.

3. Construction with minimal problems: first the right turn roads are built, then the direct intersection is closed while the bridge is being built, after which the clover is completed. Only one bridge needs to be built.

Flaws

1. Left turn 270 degrees.

2. The entrance is located before the exit, which in itself can create congestion and emergency situations (especially if public transport stops are located under the bridge).

3. Difficulties for pedestrians - to cross the junction, you need to walk a long distance and at the same time cross at least two side roads.

4. In practice, the speed on “clover leaves” is no more than 40 km/h (on other roads - higher).

Parclo (Parclo deployment)

Or partial clover. The most striking example is at the Kuntsevskaya metro station or at the entrance to Reutov.

Advantages

1. More speed than a 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 left turns

Flaws

1. Only part of the exit/exit lanes is allocated. It is impossible to select all stripes.

2. A reversal is impossible in principle.

Clover-shapedthree-level

Advantages

1. Deprived of the typical disadvantages of a clover-shaped vehicle due to the presence of left turns

2. It is possible to turn around in the basic configuration, although it is difficult

Flaws

1. Complexity of the interchange (three floors)

2. There should be no buildings nearby

3. You cannot build more than four roads at the intersection

Cumulative

The simplest four-level savings option

An interchange in which part of the lanes is separated from one road and merged into another road in the same quantity.

The simplest version is on diamond-shaped roads extending to the right, from which left-turn roads extend directly from the center. It may also have a more complex design. Complex junctions are often called "Spaghetti"

Advantages

1. There are no hostile flows, flow formation occurs before interchange

3. Can be used at any intersection of any number of roads, 6-level ones are also known

4. The ability to select roads for turning at a greater distance compared to clover-shaped ones.

Flaws

1. Complex design, high construction cost

2. Additional roads are needed for turning around

Clover-shaped cumulative

transportation cargo vehicle

Two-levelclover-shapedcumulative decoupling

In the late 1960s, clover-shaped storage interchanges began to prevail over classic clover-shaped interchanges abroad.

With this design of the interchange, the ramps have become longer, and the turning radius has accordingly increased, which allows for increased speed of movement along it. In some cases, a third level of interchange is used to lengthen short loop ramps.

Advantages

1. Cheaper than a storage interchange, only 2 levels are used for 2 highways

2. The exit is located before the entrance

4. High interchange capacity

Flaws

1. Additional turning roads are needed

2. It is necessary to construct 7 bridges

Turbine decoupling

Two-level turbine decoupling

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

Advantages

2. The exit is located before the entrance

3. The need to change lanes before exiting the highway is quantitatively reduced.

Insufficientattacks

1. Requires a lot of space to build

2. Requires the construction of 11 bridges

3. Sudden changes in elevation on ramp ramps

Mill blade type decoupling

Mill blade type

Cross type mill blade

Another alternative to the four-level storage interchange is the mill blade type interchange.

It is one of the options for turbine decoupling. A distinctive feature of such interchanges is the need for only 2 levels and the construction of only 5 bridges.

At the same time, in the version of a mill-blade cross-interchange, the throughput of the interchange increases due to the crossing of highway flows (in the case of right-hand traffic at the interchange, it becomes left-hand traffic). In addition, turns become more understandable from the point of view of a traffic participant; they are more clearly highlighted.

The interchange was named after its characteristic ramps, similar to the blades of a windmill.

Advantages

1. High throughput

2. The exit is located before the entrance

3. Requires the construction of only 5 bridges

4. Possibility of organizing turns for cross-coupling like a mill blade

Flaws

1. Turns have a smaller radius compared to turbine and storage interchanges.

2 . Pecuttingand junctions of highways

General provisions and requirements for the design of intersections and junctions at one level

Mandatory elements of highways are intersections and junctions at the same and different levels.

The main feature of intersections and junctions of highways at the same level is the presence within their boundaries of a significant number of conflict points formed by the branching, merging and intersection of traffic flows in different directions. The concentration of a large number of conflict points on a relatively small area of ​​intersections and junctions at one level (especially unregulated ones) sharply increases the likelihood of road traffic accidents (RTA).

The total number of conflict points increases markedly with the number of lanes in each direction. Therefore, planning solutions for intersections and junctions should be such that the total number of conflict points is reduced to the possible minimum. A radical solution to improve traffic conditions and safety at intersections is the construction of traffic junctions at different levels. However, such solutions, as a rule, turn out to be appropriate and economically justified at intersections of high-category highways. In other cases, to reduce the number of conflict points, canalized intersections are provided at one level by introducing safety islands to separate traffic flows in directions (Fig. 18.1).

Rice. 18.1. solution in terms of crossing roads of III and IV-V categories at one level:

a - intersection plan; b - transitional express lane

When developing a project for a road intersection, a planning decision is made depending on the prospects for the development of intersecting roads. In this case, the following factors are taken into account: the spatial position of the intersection node, its location in the road transport network, consistency with other types of interchanges and traffic organization, its visibility, clarity and understandability to the driver. Therefore, when placing and constructing intersections and junctions on newly designed and reconstructed roads, they are guided by the following requirements, aimed primarily at increasing traffic safety.

1. Possible intersections are identified along the route of the designed road, their necessity and feasibility are studied, if possible, they are limited to a minimum number, making maximum use of parallel and on-farm roads. In accordance with SNiP 2.05.02-85, the distance between intersections should, as a rule, be at least 2 km.

3. Along the route of the designed road, whenever possible, similar planning solutions are provided at junctions and intersections with other roads.

4. When designing the plan and longitudinal profile of a highway at intersections, they strive to ensure maximum visibility depth and visibility of intersection nodes. For this purpose, the following are provided: intersection angles close to 90°; the location of intersections in plan on straight sections, in profile - on concave vertical curves and longitudinal slopes of no more than 20 ‰, which in some cases requires changing the longitudinal profile of the secondary road; crossing a minor road in a low place; removing obstacles from the visibility zone. If it is impossible to ensure direct visibility of the road being crossed within the intersection, structural and planning solutions provide a visual representation of the direction of the road (tree plantings, gaps in roadside forest plantations, etc.).

5. Within intersections, the use of limit values ​​of longitudinal and transverse slopes, curves in plan and longitudinal profile of minimum radii is not allowed.

The longitudinal profile of the secondary road must be subordinated to the transverse slope of the carriageway of the main road. Possible solutions for the design line of the longitudinal profile of a secondary road are shown in Fig. 18.2. With large longitudinal slopes on a secondary road, you can refuse to connect the roadway of the main road with a vertical curve with a given slope and allow a direct connection of the secondary road with a slope that is conducive to reducing the volume of excavation work, if the difference in slopes at the junction points does not exceed 40 ‰ (see Fig. 18.2. b, c). It is recommended to take the minimum radii of vertical curves for such solutions: for convex curves 500 m, for concave curves - 200 m. However, in all cases, a check for visibility conditions is required.

Rice. 18.2. solutions to the design line of the longitudinal profile of the secondary road at its intersection with the main road: a - the secondary road is mated with a vertical curve to the roadway of the main road: the longitudinal slope of the junction road is equal to the junction with the transverse slope of the main road, in some cases a large volume of earthworks is possible; b - the secondary road is connected by a straight section to the roadway of the main road: the longitudinal slope of the connecting road section is directed in the direction opposite to the transverse slope of the main road, the solution helps to reduce the volume of earthworks; c-the secondary road is connected by a vertical curve to the roadway of the main road, the profile slope of the junction road is zero, the solution helps to reduce the volume of earthworks;

1 - carriageway of the main road; 2 - longitudinal profile of the earth; 3 - design line of the longitudinal profile of the secondary road

The intersection is considered convenient for traffic provided that no difficulties arise when making turning maneuvers by heavy vehicles and road trains. For these purposes, the minimum radii of curvatures should be set to at least 30 m. To prevent incorrect actions by drivers within the intersection, it must be extremely clear to the driver.

The placement of road signs and indicators at intersections is carried out in accordance with current GOSTs and rules.

3 . Clclassification of highway intersections at different levels and requirements for them

Intersections and junctions of highways at different levels are the most complex nodes of highways, both from the point of view of design and from the point of view of their construction and subsequent operation. The cost of traffic interchanges at different levels is very high. In this regard, the issue of creating modern technology and methods for designing intersections and junctions of highways at different levels is very relevant. The implementation of modern technology and methods for designing traffic interchanges at different levels based on the use of powerful computer equipment equipped with the necessary peripheral devices allows us to obtain the best design solutions with minimal costs and time for design.

According to current design standards, the need to construct intersections and junctions of highways at different levels is provided for in the following cases:

at intersections of category I roads with roads of other categories;

at intersections of roads of category II with roads of categories II and III;

at intersections and junctions of category III roads with each other, with a total estimated traffic intensity for both roads of more than 8,000 ghost units/day.

The current regulatory documents for the design of highway intersections impose the following requirements:

traffic junctions at different levels on highways of categories I-II are designed in such a way that intersections of left-turn traffic at the same level with traffic flows in the main directions are excluded;

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

elements of branches and junctions, in order to ensure comfortable and safe conditions for the movement of branching and merging traffic flows, as well as in order to reduce the area occupied by a transport hub, are designed based on the conditions of traffic of cars at variable speeds. At the same time, the minimum radii of curves at right-turn exits from roads of categories I-II are determined based on ensuring a speed of at least 80 km/h, and from roads of category III - at least 60 km/h. Minimum radii on left-turn exits from roads of categories I and II are determined based on ensuring a speed of 50 km/h and from roads of category III at least 40 km/h;

exits from and entrances to roads of I-III categories are carried out with the construction of transitional and express lanes;

The width of the roadway along the entire length of left-turn ramps is 5.5 m, and on right-turn ramps 5.0 m. The width of the shoulders on the inside of the curves on ramps must be at least 1.5 m, and on the outside - 3.0 m;

longitudinal slopes on the connecting ramps of interchanges are no more than 40 ‰. The radii of vertical curves in the longitudinal profile are assigned depending on the design speed at the exits.

The need to build traffic interchanges at different levels is determined by the requirements to ensure continuous, safe and comfortable movement of traffic flows at high speeds, which can be achieved by eliminating intersections of traffic flows at one level. In the domestic practice of highway design, transport intersections in two levels and, much less frequently, in three and four levels have become widespread. Most often, traffic interchanges are arranged at two levels, as they are the cheapest and, in most cases, radically solve the problem of continuous and safe movement of traffic flows at intersections and junctions of highways.

The variety of local conditions at intersections and junctions (features of the plan and profile of intersecting roads, angles of intersections or junctions, situational features of the intersection, categories of intersecting roads and distribution of future traffic intensity in directions, topographical, engineering-geological, hydrogeological conditions, etc. ) predetermined a wide variety of possible types of junctions and road intersections at different levels. Currently, about 200 interchange schemes at different levels are known.

Nodes of intersections and junctions of highways at different levels can be divided into the following groups according to their plan layout and methods of organizing traffic on them:

clover-shaped (Fig. 18.3);

ring (Fig. 18.4);

loop-shaped (Fig. 18.5);

cruciform (Fig. 18.6);

diamond-shaped (Fig. 18.7);

complex intersections with semi-straight and straight (directional) left-turn exits (Fig. 18.8);

abutments (Fig. 18.9).

Rice. 18.3. Scheme of clover-shaped transport intersections at two levels:

a - full clover leaf; b - compressed clover leaf; c, d, e, f, g - incomplete clover leaf

Rice. 18.4. Schemes of ring traffic intersections at two levels:

a - turbine type; b - distribution ring with five overpasses; c-distribution ring with three overpasses; d - distribution ring with two overpasses.

Rice. 18.5. Schemes of loop-shaped transport intersections at two levels:

a - double loop; b - improved double loop

Rice. 18.6. Scheme of cross-shaped transport intersections at two levels:

a - intersection with five crossovers; b - intersection with assigned left turns

Rice. 18.7. Diamond-shaped traffic intersections at different levels:

a - with straight left turns; b, c-c semi-straight left turns; g - in four levels

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

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

Rice. 18.9. Schemes of transport connections at two levels:

a, b - complete connection of the “pipe” type; c-full connection with two semi-straight left-turn exits; d, e, f - incomplete junctions

In the practice of domestic design, clover-shaped intersections of highways at different levels are most widespread. At the same time, there are interchanges of the “full cloverleaf” type, which provides complete traffic flow in all directions (see Fig. 18.3, a), “compressed cloverleaf”, arranged in cramped urban conditions (see Fig. 18.3, b) and “incomplete cloverleaf”, allowing intersections at one level of left-turn traffic flows on secondary directions (see Fig. 18.3, c, d, e, f, g).

The advantages of clover-shaped intersections include: 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.

However, clover-shaped junctions at highway intersections also have some disadvantages that limit their scope of application: the large area occupied by the interchange; significant overruns for left-turn traffic flows and flows making a U-turn; the need for additional measures to ensure the safe movement of pedestrians.

Ring intersections of highways (see Fig. 18.4) are characterized by the greatest simplicity of traffic organization, but require the construction of two to five overpasses, as well as a large area of ​​land acquisition.

Loop-shaped intersections, for example, a “double loop” (Fig. 18.5, a) or an “improved double loop” (Fig. 18.5, b), are arranged at the intersection of highways or main streets with secondary roads. The disadvantages of this type of intersection, in addition to the need to build two overpasses, also include insufficient provision of safe traffic conditions, since the traffic flow from the main highway flows into secondary flows not from the right, but from the left.

In cramped conditions of urban development, cruciform intersections are used at different levels, for example, of the “cross” type (Fig. 18.6, a), an intersection at two levels with assigned left turns (Fig. 18.6, b), etc. Cross-type intersections with five overpasses are used in cramped conditions when crossing equivalent highways with powerful traffic flows. In addition to the minimum area of ​​occupied land, this type of intersection is characterized by minimal re-traffic for left- and right-turn traffic, but requires the construction of five overpasses (though smaller in width than for a cloverleaf intersection) and eliminates the possibility of a U-turn within the transport hub. A two-level intersection with separated left turns is often used in the context of existing urban development on main highways with small left-turn traffic.

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

Complex intersections with semi-straight and straight left-turn exits are arranged on intersecting highways in the presence of one (see Fig. 18.8, a, b, c) or several (see Fig. 18.8, d) powerful left-turn traffic flows, when the construction of a regular exit (see Fig. 18.3, a) predetermines unjustified losses associated with over-mileage of cars. Reducing or eliminating overruns is achieved by constructing, respectively, semi-straight or straight left-turn ramps, which predetermines a noticeable increase in the construction cost of the transport interchange due to the need to build two additional overpasses.

The junctions of highways at different levels are divided into complete (see Fig. 18.9, a, b, c), providing traffic interchange in all directions, and incomplete, having areas of intersection of traffic flows at the same level (see Fig. 18.9, d, e ) or weave zones (Fig. 18.9, e). In the practice of domestic highway design, the most widespread junctions at different levels are of the “pipe” type (see Fig. 18.9, a, b). This type of connection provides traffic decoupling in all directions while alienating a relatively small area of ​​land and low construction costs. However, the “pipe” type connection has a significant drawback - it does not provide the ability to turn.

4 . AlElements of highway intersections at different levels

Any intersection of highways of any complex outline in plan can be represented by a combination of a very limited number of geometric elements (Fig. 18.10), the classification of which was proposed by V.A. Fedotov.

Rice. 18.10. Geometric elements of highway intersections at different levels:

PSP - transitional high-speed lane; PC - transition curve; CL - clothoid; CC - circular curve; P - straight

Transitional high-speed lane (TPB). Elements of intersections are designed for lower vehicle speeds (see Section 18.1) than on intersecting roads. To ensure safe entry of cars into the intersection, as well as for exit from the intersection onto the road, an additional lane is installed, called a transitional lane, along the length of which cars are slowed down to a safe speed for entering the intersection or cars are accelerated to the speed of traffic flow on the road. The length of the transitional high-speed lanes is determined from the condition of braking (or acceleration) from speed V1 on the highway to speed V2 entering the intersection:

V1, V2 - speeds on the highway and at the entrance to the intersection, respectively, km/h;

a is the acceleration of cars, taken within the range of 0.8 - 1.2 m/s2 during acceleration and 1.75 - 2.5 m/s2 during braking.

According to the current Building Codes and Rules, the length of full-width transitional speed lanes (at 0 longitudinal slope) is:

Transition curve (SC). To ensure a smooth transition of the car from the straight section of the transitional high-speed lane (R = Ґ) to the section of the connecting ramp with maximum curvature (R = Rк) and, conversely, from the condition of a gradual change in centrifugal acceleration, transition curves are used. In contrast to the roundings of stretch sections of highways, where as transition curves, as a rule, a clothoid is used, characterized by a linear law of change in curvature and increase in centrifugal acceleration and meeting the conditions for the movement of cars along it at a constant (design) speed, in sections of branches and junctions of traffic interchanges At different levels, special types of transition curves are used, the laws of change in curvature of which best meet the conditions of vehicle movement at variable speeds. These types of transition curves will be discussed in detail in the next chapter.

Clotoid (CL) also finds application in the design of connecting ramps for transport interchanges, mainly right-turn and directional ones.

Circular curve (CC). Sections of connecting ramps with maximum curvature are described in plan along circular curves. At the same time, cars within these areas move at a minimum constant speed.

Straight (P). As when designing a highway plan, when routing right-turn and directional connecting ramps, a straight line is also often used as an independent element of the route. In this case, the straight line is conjugated with adjacent circular curves, usually through clothoids.

The most complex and critical places for traffic interchanges at different levels are the zones of branches and junctions of the right and left-turn connecting ramps between intersecting highways (Fig. 18.11). Constructive solutions for sections of branches and junctions largely determine traffic safety, throughput and the general dimensions of the entire interchange as a whole.

5 . Alintersection elementsth on branches and junctions

ZTR - transport interchange zone; ZO - branch zone; SB - branch section; ZP - abutment zone; UP - junction area; RP - dividing strip; OU - broadening stripping; P - area of ​​separation of edges and edges

The traffic interchange zone (TIZ) is determined by the position of the starting points for the expansion of the widening.

Branch zone (SB) - a section at the exit from the highway from the starting point of the widening of the transition lane to the end point of separating the edges of the roadways.

The abutment zone (JZ) is the area at the entrance to the highway from the end of the separation of the edges to the start of the widening of the transition lane.

Branch section (SB) - a section at the exit from the highway from the point where the widening of the transition lane begins to be separated to the point where the edges begin to separate.

The junction section (AP) is the section at the entrance to the highway from the point at which the edges begin to separate to the point at which the widening of the transition lane begins.

The widening section (WU) is the section of transition from the unwidened carriageway of the highway to the beginning of the full-width transitional express lane.

Section of separation of edges and edges (P) - sections of exits and entrances, within which the separation of edges and edges of the highway and the connecting ramp is carried out.

Planning solutions for traffic interchanges at different levels include a certain set of connecting ramps between intersecting roads. According to V.A. Fedotov, depending on the type of maneuvers performed and the nature of the outline in plan, the following types of connecting ramps are distinguished (Fig. 18.12):

for traffic when changing directions to the right - right turn ramps (RRP);

for movement when changing directions to the left - Loop ramps (PER), right-hand ramps (RSR), left-hand ramps (LSR), right-left ramps (PLSR), left-right ramps (LPSR), ring ramps (CR).

The use of the listed types of connecting ramps makes it possible to build almost any interchange. For example, the use of four PPR type ramps and four PER type ramps leads to the classic “cloverleaf” pattern, etc.

6 . Problems solved when designing traffic interchanges at different levels

Despite the well-known commonality of problems solved when designing traffic interchanges at different levels and highways, the design of interchanges has a number of specific features. So, for example, if a highway is a linear structure, then traffic junctions are located in areas whose dimensions can reach 50 hectares or more. The variety of interchange schemes, the alternative choice of planning and design solutions taking into account local conditions and the spatial geometry of intersecting roads in the presence of a set of restrictions in the elements of the plan and longitudinal profile lead to the solution of problems that are not typical for a highway as such.

Rice. 12.18. Connecting ramps for complex transport interchanges

In recent years, technology and methods for automated design of traffic interchanges at different levels have become more developed both in Russia and abroad. This circumstance was greatly facilitated, on the one hand, by the introduction of computer technology into design practice and, on the other, by the study of vehicle traffic patterns at existing traffic junctions, which makes it possible to establish the functioning features of complex sections of junctions and draw conclusions regarding the need to change certain parameters and even principles for solving individual problems.

Despite the numerous studies carried out over the past half century on the issues of increasing the reliability of the functioning of interchange elements, engineering calculations with the existing traditional design technology are carried out separately, without spatial interconnection of elements and control over the manifestation of physical indicators of traffic, which largely determine the levels of traffic convenience and safety and the throughput of intersections and adjacencies. The general picture of traffic junctions at different levels in their spatial embodiment is much more complex than schematized representations of elements in individual planes. Mathematical description of the interaction of the geometry of connecting ramps with mating sections of intersecting highways in three-dimensional space with simultaneous monitoring of changes in physical parameters of movement (longitudinal speeds and accelerations, the degree of change in centrifugal acceleration with constant and variable speeds, changes in the angular speed of rotation of the car around the longitudinal axis when driving on turn, etc.) leads to complex design, the practical implementation of which is possible only with the use of modern computer technology.

Designing traffic interchanges at different levels is an extremely busy process (the development of one intersection design takes up to 5 months), which, within the framework of traditional technology, practically eliminates the alternative search for an optimal solution. In this regard, the use of computer technology in calculations is advisable at all stages of design. The use of computers in the design of traffic intersections at different levels provides an economic effect, which is expressed in the following:

reduction of time, labor intensity and cost of design. The use of modern computers equipped with high-speed and high-precision tablet-type plotters and monitors makes it possible to automate the labor-intensive processes of calculating elements of transport interchanges when solving them in an integrated setting, calculating the volume of work, transportation and operating costs, as well as calculations performed during the technical and economic comparison of planning options and design solutions, automate the process of obtaining design and estimate documentation in the form of ready-made drawings, tables, estimates, etc.;

reducing the estimated cost of constructing traffic interchanges at different levels by up to 10% or more. Interchanges at different levels are very expensive structures, and the issue of possible reduction in their construction cost is very relevant. The ability to develop a large number of options for planning and design solutions using computer-aided design in a short time allows you to choose the best one in relation to the capital intensity of construction;

improving the quality of design solutions. Analysis in dialogue mode with a computer of options for solving traffic interchanges allows you to select solutions that provide the necessary crossing capacity, the best levels of traffic convenience and safety, minimal transport and operating costs, etc.;

eliminating design errors. During the preliminary design of traffic interchanges at different levels at the early stages of design, in the case of using traditional technology (without spatial interconnection of elements and control of physical parameters of traffic), gross miscalculations are often made, requiring at subsequent stages of detailed design a forced change in the fundamental decisions of the intersection layout and not previously envisaged increase in the estimated cost of construction.

The use of computer technology to solve traffic interchanges at different levels cannot follow the path of formally borrowing methods of traditional technology. First of all, this applies to: the pairing of elements in plan and longitudinal profile; to the use of various types of transition curves; to the representation of the relief and geological structure of the area in the form of digital and mathematical models; to the calculation of the edges of the roadway, parallel and non-parallel to the axis and widenings; to establish the spatial position of the elements of the structure, etc. All calculations in a complex formulation must be interconnected.

Issues of integrated, automated design of traffic interchanges at different levels have been developed in recent years in the works of Soyuzdorproject (PhD V.A. Fedotov), ​​in which, in particular, foreign experience in design, construction and operation is generalized and largely developed interchanges. In domestic systems for computer-aided design of highways CAD-AD, special systems and application software packages are devoted to this important issue. A technological diagram of the integrated spatial design of traffic interchanges at intersections and junctions of highways at different levels using computer technology is presented in Fig. 18.13.

Rice. 18.13. Technological diagram of integrated automated design of traffic interchanges at highway intersections at different levels

In accordance with the technological sequence of the integrated design of intersections and junctions of highways at different levels, the following main groups of problems are solved sequentially or simultaneously:

pairing of geometric plan elements in the axes and edges of roadways;

establishing the design line of the longitudinal profile along the connecting ramps;

vertical layout solution;

calculation of the volume of excavation, strengthening work, work on the construction of road pavement and artificial structures;

determination of the estimated cost of construction;

determination of transportation and operating costs and reduced costs; graphic, tabular and text design of project material.

7 . Ananalysis of intersection conditions when designing interchanges

When choosing the type of interchange, you must have the following data: categories of intersecting roads;

a cartogram of the intensity and composition of traffic in directions for the first stage of construction and for the future;

a plan of the territory adjacent to the intersection in coordinates and the corresponding digital and mathematical models of the area;

materials characterizing the geological and hydrogeological conditions of the area adjacent to the intersection, as well as the corresponding digital and mathematical models of the geological and hydrogeological structure of the area;

data on the plan, installation depths and technical characteristics of underground communications;

data on the spatial geometry of intersecting roads (plan, longitudinal and transverse profiles);

data on the design of pavement on intersecting roads;

data on the conditions and volume of pedestrian traffic;

other requirements arising from the specific local conditions.

Based on the listed data, a traffic management scheme at a transport intersection is designed, taking into account the best levels of traffic convenience and safety, ensuring the necessary throughput, as well as the minimum cost of construction and transport and operating costs. Important requirements for choosing the type of interchanges are imposed from the architectural and compositional linkage of the structure with the buildings adjacent to the junction and the surrounding landscape.

The choice of the type of interchanges, planning and design solutions of their elements are significantly influenced by the following main factors.

The category of intersecting roads is associated with design speeds on connecting ramps, which in turn determine the permissible radii of curvature in terms of left-turn and right-turn connecting ramps, as well as the permissible radii of vertical convex and concave curves of longitudinal profiles along connecting ramps. Depending on the category of intersecting roads, the length of the transitional express lanes at exits and entrances, as well as the length of the widenings, are assigned.

And finally, the ratio of speeds associated with the category of intersecting roads at the exit and at the section of the connecting ramp with maximum curvature in plan requires such planning and design solutions that would ensure the necessary levels of traffic convenience and safety.

Thus, just changing the category of intersecting roads, other conditions being equal, can greatly deform the planning solution of the interchange and lead to other design solutions.

Intensity and composition of movement. The intensity of traffic, its distribution in directions and the composition of traffic have a decisive influence on the choice of the type of intersection or junction at different levels, as well as on the planning and design solutions of its elements. One of the main requirements for traffic interchanges at different levels is uninterrupted operation at any time of the year, month, day of the week and hour of the day. Therefore, in transport calculations, maximum traffic volumes in all directions during rush hour are taken for the busiest season of the year and day of the week.

To select an intersection or junction scheme, it is convenient to use a graphical representation of traffic intensity in the form of cartograms of traffic flows indicating their sizes in the given units (Fig. 18.14). For this purpose, the actual traffic intensity in physical units is reduced to the intensity of a homogeneous traffic flow, represented only by passenger cars:

Rice. 18.14. Cartogram of traffic intensity at a transport intersection of highways during rush hour

Ni is the traffic intensity of the i-th brand, vehicle/hour;

ai is the reduction coefficient determined for each type of vehicle, respectively:

Passenger cars………………………….1

Trucks with carrying capacity, t:

up to 3……………………………………………………1.5

5…………………………………………………………..2

8………………………………………………………….. 2,5

over 8…………………………………………………………….. 3.5

Buses…………………………………………………………….. 2.5

Trolleybuses……………………………………………………3

Articulated buses and trolleybuses……4

Motorcycles and mopeds……………………………0.5

Cartograms of traffic intensity, built for various design years, make it possible to solve the issues of phasing construction, when, as intensity increases, they provide for the possibility of transforming incomplete type interchanges into intersection nodes, providing complete decoupling of traffic in all directions without conflict points.

Plan of the surrounding area. Situational features of the territory adjacent to the transport hub (existing urban development, railways, territories of national economic facilities, valuable agricultural land, etc.) can greatly deform the configuration of connecting ramps in plan with a corresponding deterioration in the physical parameters of traffic flows and associated levels of convenience and traffic safety. If these parameters are outside the acceptable limits, a change in the type of decoupling is required using a solution that is acceptable within the specific situational constraints.

The topography of the area adjacent to the intersection not only largely determines the volume of excavation work, but in some cases can also influence the choice of the type of main artificial structure of the interchange (overpass, tunnel).

Geological and hydrogeological conditions. Geological and hydrogeological features of the area adjacent to a transport hub often predetermine the choice of the type of artificial structure and approaches to it (overpass or tunnel, embankment or overpass, etc.). Geological and hydrogeological conditions influence the depth of foundation of overpass supports, the choice of the type of span (slit, continuous), the design of retaining walls, determine the need for organizing drainage in tunnels, etc. All this ultimately affects the estimated cost of constructing the interchange as a whole.

Underground communications. Taking into account the location of underground communications is of particular importance when designing traffic interchanges at different levels in established cities, characterized by a dense network of main pipelines, cables, air communications, etc. Under these conditions, in many cases, the option of constructing an overpass is preferable to a tunnel.

The spatial geometry of intersecting roads in a number of cases has a decisive influence on the choice of interchange scheme and the main planning and design solutions of its elements. The intersection angles of highways, intersection conditions (when one or both intersecting highways are located on curves in plan), longitudinal and transverse profiles of highways are strict technical restrictions, within which it is necessary to find a solution that meets all current technical standards. This task often turns out to be insoluble with traditional technology. Modern CAD-AD software, as a rule, makes it possible to strictly analytically solve traffic intersections for almost any combination of plan and profile of intersecting roads.

Pedestrian traffic. The problem of taking into account the safe movement of pedestrians when designing intersections and junctions at different levels usually arises in cities. If there are pedestrian crossings at one level at a transport hub, the continuity of traffic flows is eliminated and the efficiency of traffic junctions as a whole is sharply reduced. In such cases, additional measures are envisaged, consisting of the construction of off-street pedestrian crossings.

The choice of a particular type of intersection or junction at different levels is also influenced by many other factors, such as the size of capital investments, transport and operating costs, levelized costs, efficiency of capital investments, considerations of the possibility of staged construction without waste costs, node capacity, speed of traffic flows , levels of traffic convenience and safety, left-turn traffic reruns, etc.

Conclusion

Due to the continuous increase in traffic volume on roads caused by the rapid growth of the vehicle fleet, the problem of rational design of intersections and junctions of roads becomes more and more urgent every year. These problems can only be solved through the construction of new transport interchanges and expressways.

Currently, a comparative assessment of transport interchanges has been developed from the point of view of traffic safety. In addition, the design of transport interchanges using computers is considered.

It is noted that the main technical decisions taken in projects on the laying of roads on the ground, on the elements of the plan, longitudinal and transverse profiles and their main combinations, types of intersections and junctions of roads, designs of road pavements and roadbeds should create the prerequisites for ensuring an increase in labor productivity, savings basic building materials and fuel and energy resources.

When designing highways and transport interchanges, it is necessary to provide for measures to protect the natural environment, ensuring minimal disruption of the existing environmental, geological, hydrogeological and other natural conditions. When developing measures, it is necessary to take into account respect for valuable agricultural land, recreation areas and locations of medical institutions and sanatoriums. The location of bridges, design and other solutions should not lead to a sharp change in river regimes, and the construction of the roadbed should not lead to a sharp change in the regime of groundwater and surface water flow.

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