A modern road is considered a road from. Elements of highways. And city streets

The following basic concepts and terms are used in the Rules:

"Motorway"- a road marked with the sign 5.1 ** and having for each direction of movement carriageways separated from each other by a dividing strip (and in its absence - by a road fence), without crossings on the same level with other roads, railway or tram tracks, pedestrian or bicycle paths.

"Road Train"- a motor vehicle coupled to a trailer (trailers).

"Bike"- a vehicle, other than a wheelchair, which has at least two wheels and is generally propelled by the muscular energy of the occupants of the vehicle, in particular by means of pedals or handles, and may also have an electric motor of rated maximum power in mode continuous load not exceeding 0.25 kW, automatically shutting off at speeds over 25 km/h.

"Cyclist"- the person driving the bike.

"Bicycle lane"- a road element (or a separate road) structurally separated from the carriageway and sidewalk, intended for the movement of cyclists and marked with the sign 4.4.1.

"Driver"- a person driving a vehicle, a driver leading pack, riding animals or a herd along the road. A driving instructor is equivalent to a driver.

"Forced Stop"- termination of the movement of the vehicle due to its technical malfunction or danger posed by the transported cargo, the condition of the driver (passenger) or the appearance of an obstacle on the road.

"The main road"- a road marked with signs 2.1, 2.3.1-2.3.7 or 5.1, in relation to a crossed (adjacent), or paved road (asphalt and cement concrete, stone materials, etc.) in relation to a dirt road, or any road in relation to departures from adjacent territories. The presence of a paved section on a secondary road immediately before the intersection does not make it equal in value to the crossed one.

"Daytime Running Lights"- external lighting devices designed to improve the visibility of a moving vehicle in front during daylight hours.

"Road"- a strip of land or the surface of an artificial structure, equipped or adapted and used for the movement of vehicles. The road includes one or more carriageways, as well as tram tracks, sidewalks, shoulders and dividing lanes, if any.

"Road traffic"- a set of social relations that arise in the process of moving people and goods with or without vehicles within the roads.

"traffic accident"- an event that occurred during the movement of a vehicle on the road and with its participation, in which people were killed or injured, vehicles, structures, cargo were damaged, or other material damage was caused.

"Railroad crossing"- crossing the road with railway tracks at the same level.

"Route vehicle"- a public transport vehicle (bus, trolley bus, tram) designed to transport people on the roads and moving along an established route with designated stops.

"mechanical vehicle"- a vehicle, other than a moped, propelled by an engine. The term also applies to any tractors and self-propelled machines.

"Moped"- a two- or three-wheeled motor vehicle, the maximum design speed of which does not exceed 50 km/h, which has an internal combustion engine with a displacement not exceeding 50 cubic meters. cm, or an electric motor with a rated maximum power in continuous load mode of more than 0.25 kW and less than 4 kW. Quadricycles are equated to mopeds, having
similar specifications.

"Motorbike"- a two-wheeled motor vehicle with or without a side trailer, the engine capacity of which (in the case of an internal combustion engine) exceeds 50 cubic meters. cm or the maximum design speed (for any engine) exceeds 50 km/h. Tricycles are equated to motorcycles, as well as quadricycles with a motorcycle seat or motorcycle handlebars.
type, having an unladen mass not exceeding 400 kg (550 kg for vehicles intended for the carriage of goods) excluding the mass of batteries (in the case of electric vehicles), and a maximum effective engine power not exceeding 15 kW.

"Locality"- built-up area, the entrances to and exits from which are marked with signs 5.23.1, 5.23.2, 5.24.1, 5.24.2, 5.25, 5.26

"Insufficient Visibility"— the visibility of the road is less than 300 m in conditions of fog, rain, snowfall and the like, as well as at dusk.

"Overtaking"- ahead of one or more vehicles associated with the exit to the lane (side of the carriageway) intended for oncoming traffic, and subsequent return to the previously occupied lane (side of the carriageway).

"Roadside"- an element of the road adjacent directly to the carriageway at the same level with it, differing in the type of coverage or marked out using markings 1.2.1 or 1.2.2, used for driving, stopping and parking in accordance with the Rules.

"Limited Visibility"— the driver's visibility of the road in the direction of travel, limited by the terrain, the geometric parameters of the road, vegetation, buildings, structures or other objects, including vehicles.

"Moving Danger"- the situation that arose in the process traffic, at which the continuation of movement in the same direction and at the same speed creates a risk of an accident.

"Dangerous Goods"- substances, products made from them, wastes of production and other economic activities, which, due to their inherent properties, may pose a threat to human life and health during transportation, harm environment damage or destroy property.

"Advance"- the movement of the vehicle at a speed greater than the speed of the passing vehicle.

"Organized transportation of a group of children"- organized transportation of eight or more children in a bus that is not a shuttle vehicle.

"Organized Foot Column"- a group of people designated in accordance with paragraph 4.2 of the Rules, moving together along the road in one direction.

"Organized transport column"- a group of three or more motor vehicles following directly one after another along the same lane with constantly on headlights, accompanied by a lead vehicle with special color schemes applied to the outer surfaces and flashing beacons of blue and red colors.

"Stop"- deliberate cessation of the movement of the vehicle for up to 5 minutes, as well as for more, if it is necessary for boarding or disembarking passengers, or loading or unloading the vehicle.

"Safety Island"- an element of the road arrangement that separates the traffic lanes of opposite directions (including the lanes for cyclists), structurally separated by a curb stone above the carriageway of the road or marked by technical means of organizing traffic and intended to stop pedestrians when crossing the carriageway. A safety island may include a part of the dividing strip through which a pedestrian crossing is laid.

"Passenger"- a person, other than the driver, who is in the vehicle (on it), as well as a person who enters the vehicle (gets on it) or leaves the vehicle (gets off it).

"Parking (parking space)" - a specially designated and, if necessary, equipped and equipped place, which is, among other things, a part of a highway and (or) adjacent to a carriageway and (or) a sidewalk, a roadside, an overpass or a bridge, or which is part of an underpass or underbridge spaces, squares or other objects of street road network, buildings, structures or structures and intended for organized parking of vehicles on a paid basis or without charging a fee by decision of the owner or other owner of the motor road, the owner of the land plot or the owner of the relevant part of the building, structure or structure.

"Crossroads"- a place of intersection, junction or branching of roads at the same level, limited by imaginary lines connecting, respectively, opposite, the beginnings of the curvature of the carriageways, which are the most distant from the center of the intersection. Exits from adjacent territories are not considered intersections.

"Rebuilding"- exit from the occupied lane or occupied row while maintaining the original direction of movement.

"A pedestrian"- a person who is outside the vehicle on the road and does not work on it. Persons moving in wheelchairs without an engine, driving a bicycle, moped, motorcycle, carrying a sledge, cart, baby or wheelchair, as well as using roller skates, scooters and other similar means for movement are equated to pedestrians.

"Crosswalk"- a section of the carriageway, tram tracks, marked with signs 5.19.1, 5.19.2 and (or) markings 1.14.1 and 1.14.2 and allocated for pedestrian traffic across the road. In the absence of markings, the width of the pedestrian crossing is determined by the distance between signs 5.19.1 and 5.19.2.

"Footpath"- a strip of land equipped or adapted for pedestrian traffic or the surface of an artificial structure, marked with the sign 4.5.1.

"Pedestrian zone"- the territory intended for the movement of pedestrians, the beginning and end of which are marked respectively by signs 5.33 and 5.34.

"Pedestrian and bicycle path (bike path)"- a road element (or a separate road) structurally separated from the carriageway, intended for separate or joint movement of cyclists with pedestrians and marked with signs 4.5.2-4.5.7.

"Lane"- any of the longitudinal lanes of the carriageway, marked or not marked with markings and having a width sufficient for the movement of cars in one row.

"Bicycle lane"- the lane of the carriageway intended for the movement of bicycles and mopeds, separated from the rest of the carriageway by horizontal markings and marked with the sign 5.14.2.

"Advantage (priority)"- the right to priority movement in the intended direction in relation to other participants in the movement.

"Let"— an immovable object on the lane (faulty or damaged vehicle, defect in the roadway, foreign objects, etc.) that does not allow you to continue driving along this lane. A traffic jam or a vehicle that has stopped in this lane in accordance with the requirements of the Rules is not an obstacle.

"Surrounding area"- the territory directly adjacent to the road and not intended for through traffic of vehicles (yards, residential areas, parking lots, gas stations, enterprises, etc.). Movement on the adjacent territory is carried out in accordance with these Rules.

"Trailer"- a vehicle not equipped with an engine and intended to be driven in combination with a power-driven vehicle. The term also applies to semi-trailers and drop trailers.

"Roadway"- an element of the road intended for the movement of trackless vehicles.

"Dividing Line"- an element of the road, allocated constructively and (or) using markings 1.2.1, separating adjacent carriageways and not intended for the movement and stopping of vehicles.

"Permitted maximum weight"- the mass of the equipped vehicle with cargo, driver and passengers, set by the manufacturer as the maximum allowable. For the permitted maximum mass of the composition of vehicles, that is, coupled and moving as a whole, the sum of the permitted maximum masses of the vehicles included in the composition is taken.

"Adjuster"- a person duly endowed with the authority to regulate traffic using the signals established by the Rules, and directly exercising the specified regulation. The traffic controller must be in uniform and (or) have a distinctive badge and equipment. Regulators include employees of the police and military automobile inspection, as well as employees of road maintenance services, on duty at railway crossings and ferry crossings in the performance of their duties.

"Parking"- deliberate cessation of the movement of the vehicle for more than 5 minutes for reasons not related to the boarding or disembarkation of a passenger or loading or unloading the vehicle.

"Night time"- the time interval from the end of evening twilight to the beginning of morning twilight.

"Vehicle"- a device designed for the transport by road of people, goods or equipment installed on it.

"Sidewalk"- an element of the road intended for the movement of pedestrians and adjacent to the carriageway or separated from it by a lawn.

"Give way (do not interfere)"- a requirement meaning that a road user must not start, resume or continue driving, perform any maneuver, if this may force other road users who have an advantage over him to change direction or speed.

"Road user"- a person directly involved in the process of movement as a driver, pedestrian, passenger of a vehicle.

"School bus"- a specialized vehicle (bus) that meets the requirements for vehicles for transporting children, established by the legislation on technical regulation, and owned or otherwise legally owned by a preschool educational or general educational organization.

After studying this chapter, the student should:

know

• regulations and theoretical basis road design;
• normative legal and normative-technical documents in the field of road design;
• rules for the design of highways and their arrangement;

be able to

• generalize and systematize the main documents regulating the design and operation of highways;
• solve problems related to determining the parameters of roads;
• choose the most rational design solutions based on the technical and economic comparison of options;

own

• skills in working with regulations and scientific literature in the field of design and operation of highways;
• skills in solving practical problems on the calculation of the parameters of roads.

Road classification. Main elements of highways

Road transport occupies an increasingly important place in the transportation of goods and passengers. There is a constant increase in the volume and distance of road transport.

Main technical and economic features of road transport are the following:

• - high mobility (maneuverability that allows you to quickly concentrate vehicles in the required quantity, and, if necessary, quickly transfer them to another place);
• - the ability to receive cargo and passengers directly at the place of their formation without intermediate loading and unloading operations and transfer of passengers and deliver them to their destination door-to-door, and therefore without additional costs for these operations;
• – the possibility of servicing individual and small cargo-generating points;
• - Fairly high speeds.

The vehicle has the following requirements:

• - the possibility of safe movement of vehicles at design speeds;
• - ensuring the passage of a given prospective traffic intensity;
• - ensuring the passage of vehicles of a given carrying capacity without the accumulation of plastic deformations and the destruction of pavement within the service life of the pavement;
• – driving comfort for drivers and passengers;
• - the road should harmoniously fit into the landscape, be visible in the direction of travel, without dips, at a distance not less than the visibility distance of the car;
• - the surrounding road situation should carry the optimum information, without overloading the minds of drivers, but also without giving it the opportunity to fall into a state of inhibition.

In accordance with federal law Russian Federation dated November 8, 2007 No. 257-FZ "On highways and road activities in the Russian Federation and on amendments to certain legislative acts of the Russian Federation" highway- this is a transport infrastructure facility intended for the movement of vehicles and including land plots within the boundaries of the right of way of a highway and structural elements located on them or under them (roadbed, road surface and similar elements) and road structures that are its technological part , - protective road structures, artificial road structures, production facilities, elements of road arrangement.

Depending on the tasks to be solved, roads are classified:

• - by administrative significance;
• – conditions of travel on them and access to them;
• - functional purpose;
• - categories depending on the transport, operational and consumer characteristics.

In accordance with Federal Laws No. 257-FZ "On highways and road activities in the Russian Federation" and Kv 131-FZ "On general principles organizations of local self-government in the Russian Federation", depending on their significance, roads are divided into three groups:

• - federal significance;
• - regional or intermunicipal significance;
• – local significance (roads municipalities), which, in turn, are subdivided into rural settlement roads; roads of an urban settlement, including roads of an urban district and roads of an intracity area.

Depending on the type of permitted use, they are divided into public roads and non-public roads.

Car roads common use are intended for the movement of vehicles of an unlimited circle of persons, i.e. all participants in the movement can move on them.

Car roads non-public use are owned, owned or used by the executive bodies of state power, local administrations (executive and administrative bodies of municipalities), individuals or legal entities and are used by them exclusively for their own needs or for state or municipal needs.

Highways of general use of federal significance are the following highways:

• - connecting the capital of the Russian Federation - the city of Moscow with the capitals of neighboring states and administrative centers (capitals) of the constituent entities of the Russian Federation;
• - included in the list of international highways in accordance with international agreements of the Russian Federation.

Motor roads of federal significance may include motor roads:

• 1) interconnecting the administrative centers (capitals) of the constituent entities of the Russian Federation;
• 2) being access roads connecting public roads of federal significance, and the largest transport hubs of international importance ( seaports, river ports, airports, railway stations), as well as special objects of federal significance;
• 3) being access roads connecting the administrative centers of the constituent entities of the Russian Federation that do not have public roads connecting the relevant administrative center of the constituent entity of the Russian Federation with the capital of the Russian Federation - the city of Moscow, and the nearest seaports, river ports, airports, railway stations.

The list of public roads of federal significance is approved by the Government of the Russian Federation.

The highest executive bodies of state power of the constituent entities of the Russian Federation approve the criteria for classifying public roads as regional or intermunicipal roads and a list of these roads. Public motor roads of local significance include public motor roads, with the exception of public motor roads of federal, regional or intermunicipal significance, private motor roads.

Highways of local significance of the settlement are public roads within the boundaries of the settlements of the settlement. The list of these roads may be approved by the local self-government body of the settlement.

Highways of local significance of a municipal district are public roads connecting settlements within the boundaries of a municipal district. Their list may be approved by the local self-government body of the municipal district.

Motor roads of local significance of an urban district are motor roads of general use within the boundaries of an urban district. The list of these roads may be approved by the local self-government body of the urban district.

Private public roads include roads owned by individuals or legal entities that are not equipped with devices that restrict the passage of vehicles of an unlimited number of persons. Other private motor roads are private non-public motor roads.

Public roads, depending on the conditions of travel on them and the access of vehicles to them, are divided into motorways, express roads and ordinary roads.

To highways include roads that are not intended to serve adjacent territories. Motorways have several carriageways along their entire length and a central dividing strip not intended for traffic; they do not cross other roads, as well as railways, tramways, bicycle and pedestrian paths at the same level. Access to motorways is possible only through intersections at different levels with other roads, provided no more than every 5 km. Stops and parking of vehicles are prohibited on the carriageway or carriageways of motorways. Motorways are equipped with special rest areas and parking areas for vehicles.

Highways classified as motorways must be specifically marked as motorways.

Expressways- these are roads that have a multi-lane carriageway throughout their entire length with a central dividing strip and do not have intersections at the same level with automobile roads, railways, tramways, bicycle and pedestrian paths. Access to express roads is possible through intersections at different levels and junctions at the same level (without crossing straight lines), arranged no more than 3 km apart. Stops and parking of vehicles are prohibited on the carriageway or carriageways of express roads.

Regular roads These are motorways that are not classified as motorways and express roads. They may have one or more carriageways.

Motor roads, depending on their importance in the general transport network of the Russian Federation and the size of the estimated traffic intensity, are divided into the following categories (Table 3.1).

Table 3.1

Road classification

Roads of category I with a multi-voiced carriageway are designed for high-speed transportation of goods and passengers, linking the main economic regions of the country and the largest cities. They form the basis of the country's road network - 1.4% of the total length of roads.

Roads of II-III categories serve for long-distance road communications between individual subjects of the Russian Federation and the busiest directions within the subjects of the Russian Federation, they account for 27.6% of the total length of roads.

The road category is assigned depending on the prospective (for 20 years) estimated traffic intensity, which is taken as the average annual daily traffic intensity obtained on the basis of economic survey data, total in both directions, reduced to a passenger car according to the formula

where is the intensity by means of transport; - reduction coefficients, determined according to table. 3.2.

Table 3.2

Coefficients of reduction to a passenger carK i

Note. The reduction factors for special vehicles should be taken as for base vehicles of the corresponding load capacity.

The year of completion of the development of the road project is taken as the initial year of the billing period.

When determining the road category, in cases where the average monthly daily intensity of the busiest month of the year is more than 2 times higher than the average annual daily intensity, the latter is increased by 1.5 times when determining the road category.

The number of lanes on roads of category I is set depending on the intensity of traffic and the terrain according to Table. 3.3.

Table 3.3

Number of traffic lanes on category I roads

The entire territory of the Russian Federation climatic characteristics divided into five road-climatic zones (RCZ). The boundaries of road-climatic zones are given in App. B "Road-climatic zoning" SP 34.13330.2012.

A motor road is a complex of structures, including the motor road itself, transport interchanges at one and different levels, bus stops, recreation and parking areas, campsites and car service stations. At the intersection of permanently or temporarily operating watercourses, culverts are arranged: pipes, bridges, aqueducts. Viaducts and tunnels are arranged in rugged and mountainous terrain.

All elements of the road are placed within a strip of terrain, which is called withdrawal strip. On the transverse profile of the road (Figure 3 1), certain elements can be highlighted. The strip of the road surface, within which the movement of cars occurs, is called roadway.

Rice. 3.1.

1 - subgrade; 2 - curb; 3 – edge band; 4 – roadway; 5 - dividing strip; 6 - reinforced strip on the dividing strip

To ensure the round-the-clock movement of cars within the roadway, pavement made of high-strength materials is arranged.

Roads of category I and four lanes of category II have independent carriageways for traffic in each direction, between which a dividing lane is arranged for traffic safety.

On both sides of the roadway are roadsides ensuring the safety of vehicles. The curb consists of three sections. 1) directly at the carriageway - a reinforced edge strip, which can be run over by cars, having the same pavement design as within the carriageway; 2) further - a reinforced parking lane, intended for short-term stopping and parking of cars; 3) even further - the unreinforced part of the curb.

The lines separating the carriageway and the edge strips are called the edges of the carriageway.

To smooth the relief, the road is built on a subgrade - an embankment or a cut.

The subgrade is limited on both sides by slopes. The lines separating the shoulders from the slopes are called subgrade edges. The distance between the edges is conventionally called the width of the subgrade.

The steepness of the slopes is characterized by the coefficient of laying the slopes, defined as the ratio of the height of the slope to its horizontal projection.

To ensure surface drainage of a road located in a low embankment or recess, side ditches (cuvettes) are located on both sides of the road.

The road complex also includes various intercepting and drainage structures: upland and drainage ditches.

Overseas experience

In most developed countries, several types of classification are used. As a rule, there are four such classifications: administrative, by type of property, functional and technical. Each of them solves certain tasks. Administrative and by types of ownership are used to indicate the levels of state responsibility, as well as the method of financing road facilities. For road design purposes, functional and technical classifications are needed.

Unlike foreign ones, in domestic design standards there is no concept of a functional classification of roads.

Functional classification is used primarily for transport planning purposes. The functional classification is based on the definition of the role (function) performed by the road in the process of moving through the network. There are four main groups of roads: highways (freeway), trunk ( arterial), distribution ( collector) and local ( local) roads. This approach makes it possible to create a hierarchically built road network, in which, depending on the function performed, both the class and the technical parameters of the road are determined.

The functional classification of roads groups roads according to the nature of the transport links they provide. According to the functional classification, the standards and service levels vary according to the function of the roads, and the volume and composition of the traffic serve to refine the standards for each class. The design process in the presence of a functional classification is built according to the following scheme: the function of the road and the corresponding level of service are determined: then, for the expected traffic intensity and composition of the traffic flow, the most rational category of the road, the economically advantageous design speed and geometric parameters that provide the given level of service are selected. At the same time, two tasks are solved - the structure of the road network is formed and the required transport connection is provided. Such a scheme for planning the development of a network and designing roads has been adopted in the EU countries, the USA, and Canada.

In countries Western Europe there is a technical classification, but it does not exist on its own, but is part of the functional classification. For example, in Germany, Italy, France, the same category of road may have different technical parameters depending on its function in the national road network.

The need to apply a functional classification is noted in the Consolidated Resolution on Road Traffic of the United Nations Economic Commission for Europe of August 14, 2009. In particular, it is recommended "to establish a hierarchy of the road network at the level of infrastructure design taking into account the functions performed by each road(transit transportation, local transportation, etc.)".

Currently, work is underway in Russia to introduce a functional classification of roads.

• SP 34.13330.2012 "Road roads". Updated version of SNiP 2.05.02–85* (approved by order of the Ministry of Regional Development of Russia dated June 30, 2012 No. 266).
• SP 34.13330.2012 "Roads". Updated edition of SNiP 2.05.02-85*.

A motor road is a pavement and a subgrade on which the pavement rests. Road pavement is a multilayer structure consisting of a coating, a leveling layer, a base and an underlying layer located on the subgrade. Road pavement is made in the form of a trough profile, semi-trough or sickle-shaped with certain transverse slopes that provide water runoff.

The coating is the upper part of the clothing, which perceives the forces from the wheels of cars and is directly exposed to atmospheric precipitation. The coating must be strong, even, rough, crack-resistant, waterproof, resist plastic deformation at high positive temperatures, and resist wear well.

The base of the highway is a strong bearing part of the clothing, which, together with the coating, redistributes and reduces pressure on the additional layers or soil of the subgrade located below. Additional slope and subgrade soil should provide the possibility of movement of road-building machines on them. The subgrade soil is the carefully compacted and planned top layers of the earth base, on which layers of pavement are laid.

As a subgrade, choose the base of the laid route of the highway, arranged from the soil of its natural state. Its stability and strength ensure the normal operation and long service life of the pavement and the entire road. The steepness of the slopes depends on the stability of the soil and is determined by the ratio of the height of the slope (taken as a unit) to the laying of the horizontal projection. If there is not enough soil from the ditches for the construction of the embankment, then a reserve is created. The size of the reserves is determined based on the amount of soil required for filling the subgrade. The depth of the reserve should be 0.3 ... 1.5 m. Depending on local conditions, the reserves are located on both sides of the road. With an embankment height of more than 2 m, a strip of earth called a berm is left between the beginning of the reserve and the bottom of the slope of the embankment. The width of the berms is assumed to be at least 2 m, and it depends on the height of the embankment. Berms increase the stability of high embankments, and they are used during the construction of embankments for the passage of road vehicles and cars. The berm is given a transverse slope of 20% m to the side of the reserve for water runoff.

Depending on the type of pavement and the availability of road construction materials, pavement is used various materials coating: soils, asphalt concrete and tar-concrete mixtures, crushed stone, gravel, gravel-sand mixtures.

Soils, depending on the fractional composition, are divided into sandy, sandy, loamy and clayey. Soils containing at least 82% sandy parts and no more than 3% clayey parts are called sandy. The particle diameter of sandy soils is 2...0.05 mm. Soils containing more than 25% of clay particles with a diameter of less than 0.005 mm are called clay. Sandy loam soils include soils containing at least 50% sandy and 3 ... 12% clay particles; to loamy - soils containing 12 ... 25% of clay particles. If the soil contains more dust-like particles than sandy ones, then the word dust-like is added to the name of the soil. The particle diameter of pulverized soils is 0.05...0.005 mm.

For the construction of the roadway and the preparation of cement concrete and asphalt concrete mixtures, gravel, crushed stone and sand are used. The gravel obtained after screening and separation of sand is called varietal, it is divided into the following fractions: coarse with grain sizes 70...40; medium - 40...20; small - 20...10; fine gravel - 10.. .5 mm.

Crushed stone, depending on the size of the grains, is divided into the following fractions: 5 ... 10; 10...20; 20...40; 40...70 mm. The shape of crushed stone grains should approach cubic. The particle size of crushed stone or gravel in the preparation of cement-concrete mixtures intended for coating is no more than 40 mm. Crushed stone and gravel for cement-concrete mixtures should not contain more than 25% of flaky and needle-shaped grains, and more than 1% of dust-like and clay particles.

Natural and artificial sand is widely used for the preparation of cement concrete mixtures. Natural sand is formed from the weathering of igneous, sedimentary, or metamorphic rocks. Artificial sand is obtained by crushing durable rocks. One of the main characteristics of sand is the grain size, determined by the fineness modulus M. According to the fineness modulus, sand is divided into coarse - M more than 2.5; medium - M 2.5 ... 2; small - M 2 ... 1.5; very small - M 1.5 ... 1. Sand intended for the preparation of mixtures should contain no more than 3% dust and clay particles. Organic impurities in this sand should be absent.

In the construction of cement concrete road surfaces, Portland cement is mainly used, which, depending on the strength, is divided into five grades: 300, 400, 550 and 600. coating - grades 300 and 400.

Organic binders - materials obtained as a result of processing various types of oil, coal, resins, bituminous rock. These materials are liquid, semi-liquid or solid consistency. In road construction from organic binders, bitumen, tar, emulsions are used. In road construction, for the preparation of various mixtures, viscous bitumen is mainly used, which is divided into five grades: BND200/300. BND130/200. BND90/130, BND60/90, BND40/60 (numbers characterize the viscosity of bitumen, determined by the depth (mm) of needle penetration at a temperature of 25°C). Tar is a product of dry distillation of solid fuels. Tars are used as a binder in the construction of black gravel coatings and when mixing gravel and crushed stone materials on the roadbed. Emulsions are dispersed systems consisting of bitumen or tar droplets suspended in water, covered with a thin film of emulsifier. Emulsions contain up to 50 - 60% bitumen or tar and up to 10% emulsifier

Reinforced soils are soils resulting from the treatment with organic or mineral binders in an installation or on a road. During processing, soils acquire mechanical strength, frost and water resistance. The most suitable for strengthening are crushed stone and gravel soils, sandy loam and loam with a moisture content of 3 ... 12%. The optimal content of organic binder in each case is determined on the basis of laboratory experience. This content of binder material varies within 5...17% of the mass of the mixture. When strengthening soils with mineral binders, Portland cement of a grade of at least 400 is added to them.

Asphalt concrete mixtures - a mixture of mineral materials (crushed stone or crushed gravel, sand and mineral powder) with bitumen. Depending on the largest size of the mineral material, the mixtures are divided into sandy (particle size up to 5 mm), fine-grained (up to 15 mm), medium-grained (up to 25 mm) and coarse-grained (up to 40 mm). Asphalt concrete mixtures are divided into hot and warm and depending on the viscosity of the bitumen used and the heating temperature of the mineral materials at which they are prepared, laid and compacted. Hot and warm mixtures respectively contain viscous and liquid bitumen. The temperature of hot and warm asphalt mixes at the outlet of the mixer should be within 120...160 and 80...100°C, respectively.

Cement-concrete mixtures - a mixture of crushed stone (gravel) and sand with cement and water at a ratio and consistency determined by water-cement to obtain cement concrete of the required strength and durability. The main indicator of cement-concrete mixtures is workability, characterized by the degree of mobility (rigidity) of the mixture immediately before laying in the pavement or base. Cement-concrete mixtures are divided into rigid ones - the draft of a standard cone is 0 cm, inactive - about 3 cm, mobile 4 ... 15 cm and cast more than 15 cm.

The workability of concrete mixtures depends on a number of factors, the determining one of which is the ratio of the mass of water to the mass of cement in the mixture. The greater this ratio, the more plastic the mixture will be and the easier it can be laid in the coating and compacted. However, an increase in this ratio leads to a decrease in the density of the mixture after hardening due to the evaporation of excess water and a decrease in the strength and frost resistance of the coating.

Machines for the maintenance and repair of roads and airfields have a direct impact on the state of transport facilities, which determines the productivity and quality of the transport complex, as well as the safety of passengers and the safety of cargo.

2. Cars for summer road maintenance

a) Watering machines. Watering machines are designed for washing and moistening hard surfaces, protecting them from overheating in the hot season, purifying the air and improving the microclimate in the air space adjacent to transport highways. They can be trailed (to a wheeled tractor) or self-propelled (on the chassis of a serial truck or a chassis adapted to the purpose of the machine). The watering machine (Fig. 1.1) has a tank mounted on a trailed, semi-trailed or self-propelled chassis, a suction conduit connecting the tank to a centrifugal pump that pumps water through a distribution pressure conduit to two washing nozzles.

The nozzles are located in front of the machine on its outer sides and form two washing jets diverging in a flat fan and directed at the surface of the coating at an angle of attack. By changing the angle of attack, it is possible to achieve various effects from the jet: from washing off adherent fragments of clay soil to moistening the coating.

There are layout options for machines with an additional nozzle installed at the rear side and increasing the width of the washed strip by 10 ... 15%. The nozzles are connected to a distribution pipe, into which water is supplied through a pressure line by a centrifugal pump. Between the pump and the water intake pipe located in the tank, a filter is installed that traps foreign impurities, and a central valve that allows you to quickly stop the water supply to the pump. As a rule, the tanker is also equipped with conduits, taps and hoses for refueling from a reservoir, which can also be used when extinguishing fires.

Rice. 1.1. The layout and main units of the watering machine:

A - configuration of the washing jet; 7 - washing nozzles with a distribution pipeline; 2 - base machine; 3 - tank; 4 - neck of the tank; 5 - shells for attaching the tank to the chassis; 6 - drain pipe; 7 - additional brush equipment; 8 - bridges for servicing the tank

A filter can be installed in the filling line, which prevents solid mineral and organic particles from entering the tank together with water. Typically, self-propelled watering machines are additionally equipped with sweeping and brush equipment, which allows them to expand their scope.

A mechanical or hydrostatic transmission can be used to drive the watering equipment pump and sweeping brushes. Hydraulic cylinders are most often used to raise and lower the brush.

Rice. 1.2. Coating Cleaning Machine with Washing Ramp

A significant disadvantage of the traditional coating washing technology, in which the high kinetic energy of the washing jet is provided by its mass, is considered to be a high water consumption. An alternative can be watering equipment with a washing ramp equipped with a large number downward directed nozzles of small diameter (Fig. 1.2). The ramp is located in front of the chassis low above the surface to be treated. Water supplied to the consumable conduit under high pressure, escaping from the nozzles at high speed, acquires the kinetic energy necessary to achieve a washing effect. Suspension of mud particles

In the water, fragments of the destroyed mud crust are forcibly removed from the coating with an obliquely mounted water-cutting knife with an elastic edge.

Washers with brush equipment stand apart, designed to wash the walls of tunnels, bridges, overpasses, linear transport structures, as well as fences, signs and other elements of the road environment (Fig. 1.3, 1.4, 1.5).

Rice. 1.3. Brush-washing equipment for the care of the wheel breaker bar with the rotation of the brush in the transverse plane

Rice. 1.4. Brush-washing equipment for the care of the wheel breaker bar with the rotation of the brush in the horizontal plane

Rice. 1.5. Washing equipment for the maintenance of tunnel walls

Suspension of the brush equipment of these machines allows you to move the brushes beyond the dimensions of the machine and tilt them at different angles to the horizon, up to the vertical. The water nozzles are fixed on the brush brackets in such a way that water at any position of the brush gets on the washed surface area, moistening it and washing away the dirt. Such machines are equipped with brushes of several types at once, which allows for high-quality cleaning of surfaces of any shape. The characteristics of domestic watering machines are given in Table. 1.1.

b) Sweepers. Are intended for cleaning of firm coverings of transport constructions. They can also be used for cleaning concrete and asphalt industrial sites and driveways, cleaning road sections under repair from the remnants of the removed coating. The workflow of the sweeper consists of sweeping the surface, collecting estimates in the bins, transporting to the waste disposal site and emptying the bin. Then the cycle of operations is repeated.

The main working body of the sweeper is the brush. The most common brushes are cylindrical with a horizontal axis of rotation and the pile is placed on a cylindrical surface, and end brushes, with an axis steeply inclined to the daylight surface, and a pile on the lower end. There are, but much less common, conical brushes, with an angle at the top of up to 60 ° and the location of the pile on a conical surface, and tape brushes, in which the pile is fixed on the outer side of the chain that goes around the tension wheel and the drive sprocket.

End and conical brushes are used to clean roadside trays, which are distinguished by small transverse dimensions and the complex shape of the surface to be cleaned (Fig. 1.6).

Rice. 1.6. Scheme of operation of the end brush in the tray:

1 - machine speed; 2 - tray of the road; a) - angular speed of rotation of the brush

Cylindrical brushes perform the main volume of work on cleaning hard surfaces of roads, sidewalks, industrial sites and airfield strips. They are installed at an angle to the direction of movement of the machine between its axles or perpendicularly - behind the wheels of the rear axle. The first scheme is used on universal machines, which in the warm season are used as sweepers and watering machines (see Fig. 1.1), and in the cold season - as snow and anti-icing.

The second scheme is characteristic of specialized sweepers that are not intended for re-equipment with seasonal equipment (Fig. 1.7). Tray brushes are installed on one or both sides of the machine and tilted so that the pile cleans the coating from the outside of the machine, discarding estimates from the edge of the tray under the machine (Fig. 1.8). The linear speed of the bristles of the brushes can coincide with the speed of the forward movement of the machine or be opposite.

The transfer of estimates from the coating to the storage bin or container can be carried out in several ways. With a single-stage scheme, estimates are thrown into the hopper with a cylindrical brush, giving its particles a speed sufficient to rise to the loading slot (Fig. 1.9). If the hopper is located in front of the brush, the sweep comes off the bristle of the brush immediately after it leaves contact with the surface (the so-called direct casting), if behind, the pile lifts it along the front cylindrical wall of the casing and then the sweep falls into the bunker by inertia (reverse casting) .

Rice. 1.7. Specialized sweeper

Rice. 1.8. The end tray brush is installed at an angle to the brush being cleaned.

surfaces

Typically, such schemes are used in small-sized and universal machines, where there is no place for a special hopper loading device. Specialized and large-sized universal machines are equipped with mechanical or pneumatic-vacuum bunker loading devices.

Mechanical devices are screw, belt, scraper conveyors, or combinations thereof, evacuating estimates from the tray into which it is swept with a brush into a container or hopper (Fig. 1.10). Tray brushes, sweeping the pavement, feed the estimate to the middle of the machine, in the area of ​​​​action of the main cylindrical brush, which sweeps the pavement strip located in front of it and directs the entire estimate to the receiving tray. From the receiving tray, estimates are transferred to the bunker by a mechanical device.

Pneumatic vacuum devices operate on the principle of a vacuum cleaner, to the suction nozzle of which the estimate is fed directly by a brush (usually end face) or by a screw or scraper conveyor that feeds estimates from the brushes along the receiving tray.

They pass into two radial blades, which give an estimate of additional speed, coinciding with the direction of the transporting air stream. The separation of the estimate from the air occurs in the bunker due to a sharp change in the direction and speed of the air jet, after which the air is additionally cleaned by filters from fine dust particles.

Dedusting of the area of ​​work of the brushes occurs due to the humidification of the air by the irrigation system. In modern machines, the drive of brushes, conveyors and vacuum pumps is carried out by a hydrostatic transmission, and in older designs, partly by a hydrostatic transmission, partly by a mechanical transmission, consisting of transfer boxes with cardan shafts and chain drives.

Modern machines with pneumovacuum loading systems and fully hydraulic drive are more expensive and more difficult to operate, but they provide better cleaning quality with greater productivity and are more suitable for urban conditions that place high demands on the quietness of vehicles.

Characteristics of domestic sweepers are given in table. 1.2.

The landscaping of the roadside area and the care of the green spaces, earthen and linear structures located on it is carried out by agricultural machinery, general-purpose earthmoving and loading machines with special and standard working equipment and specialized machines for the care of forest park areas. These include seeders, mowers, equipment for cutting bushes and small forests, watering machines, machines for spraying fertilizers and chemicals, crane drilling machines, pit drills, attachments for wheeled tractors, motor graders and excavators for cleaning and restoring ditches and drainage ditches, aerial platforms for maintenance of bridges, overpasses, road signs, signs and lighting equipment.

3. Machinery for winter road maintenance

a) Plow and plow-brush snowplows. Designed for patrol maintenance of roads and current cleaning of runways and taxiways of airfields in winter. Their use is most effective on a thin layer of freshly fallen, loose and rough snow cover. Snow plows are produced mainly as attachments for bulldozers, motor graders and powerful tractors, which, thanks to their high traction and road stability, can clear the entire lane in one pass at a speed that throws snow to the side of the road.

During regular cleaning of urban and airfield territories from freshly fallen snow, plow-brush snowplows based on serial or adapted automobile chassis are most often used, which shift the bulk of the snow with a plow from the roadway towards the side of the road and clean the coating from its remnants up to 15 mm thick with a brush (Fig. 1.11). The plow is installed in front of the vehicle, and the cylindrical brush is installed under its frame, between the front and rear axles. The angle between the plow and the longitudinal axis of the machine can vary from 90° to 70°, and the brush axis is angled in plan so that the snow is swept away from the machine forward to the right shoulder. The plow consists of a blade, knives and a frame.

Rice. 1.11. Plow snow plow, with sweeping equipment and gritter: 7 - distributor of loose anti-icing materials; 2 - bunker for bulk anti-icing materials; 3 - cabin of the base vehicle; 4 - frontal oblique snow plow of variable curvature; 5 - cylindrical side-mounted sweeping brush

In the simplest and cheapest designs, the dump is a monolithic slab with a cylindrical surface. The lower edge of the blade is equipped with bolt clamps for attaching sectional rubber knives, thanks to the elasticity of which surface cleaning is improved and emergency situations are eliminated when hitting uneven surfaces, manhole covers, etc. A rotary plow frame is attached to the center of the rear wall of the blade, which allows fixing the plow relative to the coupling frames at various angles. In the simplest version, the latch is a metal pin inserted into the matching holes of the swivel and coupling frames. The coupling frame, in turn, is connected through hinges to the push rods by a traction frame attached to the chassis spars.

Push rods can be both monoblock and telescopic, with shock absorbers inside. Shock absorbers protect the frame of the base chassis from shock loads perceived by the plow. There are plows with multi-section blades that adapt to uneven surfaces, each section of which is attached to the common supporting structure by an independent lever-spring suspension that presses the section to the surface of the coating and allows it to jump over bumps, manhole covers and other obstacles.

AT last years domestic plow equipment with blades of variable height and a conical canopy appeared on the market, which prevent snow from spilling over the top of the blade and allow you to remove snow at high speeds with a snow throw distance of up to 15 m or more.

A cylindrical brush is a tube on which flat rings are put on, tightly pressed against each other, with a pile pressed along the outer edge. The assembled brush is attached to brackets suspended from the chassis frame by lift/lower hydraulic cylinders and is driven by a volumetric hydraulic motor either through a planetary gearbox built into the brush or through an external chain reducer. The brush bristles of modern machines are made of kapron monofilament, but the best quality of cleaning the coating from snow gives a stiffer and thinner wire bristle. Its use is limited by the danger posed to the pneumatic wheels of vehicles by breaking off fragments of wire pile remaining on the road.

Characteristics of domestic plow and plow-brush snowplows are given in Table. 1.3.

b) Snow loaders. Designed for the evacuation of snow masses of considerable thickness beyond the boundaries of the coating or into vehicles. Their use is most effective when cleaning snow stored in high chute and roadside shafts or piles.

Plow snow loaders (Fig. 1.12) are used mainly for reloading snow collected by snow plows into shafts on the tray part of city streets into transport. Loaders are mounted on specialized chassis assembled from standard designs and units of serial trucks. The working equipment consists of a foot feeder located in front of the loader and an inclined scraper conveyor oriented along the longitudinal axis of the machine.

The working bodies are located in a box, the wide part of which, with a paw feeder that rakes snow into the box, starts in front of the machine, and the narrow part - with a conveyor, passes over all the units of the machine and protrudes so far that a dump truck can become under it.

The paw is a curved metal plate, placed on the edge and the middle part is pivotally mounted on the crank of a rotating disk installed in the wide part of the box flush with the bottom.

Rice. 1.12. Paw snow loader

The pin in the bottom of the box, which is included in the groove in the back of the paw, forces its front edge to move along an ellipse, raking snow from the side walls of the box to the scraper conveyor. In the receiving tray of the box, two paws are symmetrically installed, moving towards them with a phase shift and overlapping the working areas of each other. Snow, raked by paws to the middle of the receiving tray of the box, falls on a chain scraper conveyor, rises to the unloading end and is unloaded into the body of a dump truck. Paw loaders are most effective when loading loose snow, since the efforts of the paws and the traction of the machine are not enough to destroy frozen or compressed snow masses.

Milling loaders (Fig. 1.13), due to the peculiarities of their working body, are effective in reloading heaps and shafts of packed and frozen snow. These loaders are equipped with a milling type feeder and an inclined scraper conveyor that feeds snow into the vehicle. The milling feeder consists of two coaxial cutters of different or equal lengths (the length depends on the location of the conveyor feed opening), each of which is a metal strip forming the edges of two- or three-start cylindrical spirals connected to the central shaft by radial spokes. Rotating, the cutters cut into the snow mass, bring down and crush its fragments and shift the snow mass to the center of the cutter casing, from where it is carried by the conveyor to the body of the dump truck.

Rice. 1.13. Snow loader with milling feeder

Rice. 1.14. Auger snow loader based on the Ural-4320-10 vehicle:

1 - screw-rotor equipment; 2 - guide apparatus of the snow thrower; 3 - working lights; 4 - engine compartment; 5 - transfer case; 6 - lever mechanism for suspension of auger-rotor equipment; 7 - support ski

Rotary augers and rotary milling loaders (Fig. 1.14) are effective in emergency clearing of roads covered with thick snow drifts as a result of heavy snowfalls or snow avalanches. These machines are equipped with augers or cutters that break up the snow mass and feed the snow to the hole in the center of the casing that covers them from behind and from the sides. Through the hole, the crushed snow mass falls on the rotor blades, which, acting on the principle of a centrifugal pump, throws it through the guide vane to the side of the road or into the vehicle body.

A guide vane is a curved metal pipe with a section decreasing towards the exit, which sets the direction of movement of the snow mass thrown by the rotor. The direction and distance of snow throwing is regulated by turning the entire pipe or its end section around the vertical and longitudinal axes.

Specifications domestic snow loaders are given in table. 1.4.

c) Anti-icing machines. Designed to maintain the adhesion properties of the coating in winter at a level that guarantees safe traffic. The most widespread method of dealing with ice is the distribution of sand, granite chips, crystalline and liquid chlorides and various combinations of these substances over the icy coating. Sand and granite chips increase the grip of wheels with an icy surface, but in heavy traffic they are quickly carried to the side of the road. Chlorides initiate the melting of ice and snow run (the freezing point of salt water is well below 0°C), but if the temperature drops sharply, it can lead to even more icing. In addition, the presence of excess water on the surface of the coating at high speeds of transport is fraught with the danger of aquaplaning.

The regular distribution of mineral materials, salts and their mixtures over the surface seriously worsens the ecological situation of roadside areas and, especially, urban areas, and their long-term use can cause irreversible poisoning of wildlife. In cities, this is accompanied by clogging of storm sewers and the destruction of coatings, buildings, engineering structures, transport and damage to personal belongings of the population. Therefore, in recent years, there has been an intensive search for alternative methods and technologies to combat the slipperiness of road and airfield pavements in winter time.

Machines for the distribution of bulk anti-icing materials, as a rule, are universal and in the warm season they are converted into watering machines. They are mounted on the chassis of serial trucks, or on specialized pneumatic wheeled chassis (Fig. 1.15).

Sand, granite chips or a mixture of sand and salt are poured into a hopper in the form of a trapezoidal prism, with the smaller base facing down. The open top of the bunker is covered with a gable grate, which plays the role of a sieve. A chain scraper conveyor (feeder) is laid along the bottom of the bunker, carrying the contents to the rear end of the bunker, where a distributing device is installed. A horizontal disk with radial vertical blades on the lower plane, covered by a casing, rotates and scatters the anti-icing material through the slots in the casing over the surrounding surface in a relatively uniform layer. Material flow rate can be controlled by feeder speed, disc rotation speed, size and orientation of shroud feed slots. The distribution of liquid chlorides is carried out from road, semi-trailer or trailer tanks for the transport of liquids, equipped with dosing and distribution systems.

Rice. 1.15. Distributor of anti-icing saline solutions on the chassis of a truck

4. Road repair machines

a) Milling machines. They allow you to plan the old coating, texture its surface, restoring the adhesion properties, remove the old coating layer by layer or to the full depth, open underground utilities, release well hatches from the old coating, level concrete floors in industrial premises (Fig. 1.16). If necessary, the milling machine allows you to cut seams in the coating and underlying layers, preventing cracking or slipping of the coating around the repaired area.

The material cut from the old asphalt concrete pavement can be placed in the lower layers of the pavement or used as an additive in the preparation of fresh asphalt concrete mix.

Rice. 1.16. Self-propelled planer cutter on a four-track crawler chassis with a milling width of up to 2000 mm

For milling the pavement in small areas, around well hatches, close to the curbstone, removing road markings, cutting seams and crevices, and making “shaking” strips on highways, specialized small milling machines are used with a milling width of not more than 1000 mm (Fig. 1.17), which can be equipped with various types of milling drums. The speed of the milling drum depends on the speed of the machine and the strength of the coating.

Fastening carbide cutters in the holders ensures their quick replacement without the use of special equipment. Milling machines of the smallest size groups leave the cut material on the road, others are equipped with belt conveyors for loading the cut material into vehicles or reloading it to the roadside. The drive of the working bodies and running equipment of small machines, as a rule, is completely hydraulic, although some models can be equipped with a V-belt cutter drive. The area to be milled is usually located between the machine propellers (exceptions are allowed when milling close to obstacles or when using narrow cutters and large-diameter saw blades).

Figure 1.17. Self-propelled milling planner on a three-bearing wheeled chassis with a milling width of up to 600 mm.

The machines are equipped with a humidification system for the milled area, which provides dust suppression and cooling of the cutting tool. The smallest milling cutters can be mounted on a three-wheeled chassis with an articulated frame and the removal of the cutter beyond its dimensions.

In combination with the possibility of a transverse inclination of the milling drum, this allows you to process the coating close to straight AND curved (with a radius of 300 mm) obstacles, mill V-shaped surfaces, cut curved seams and slots in the coating.

The automated control system informs the operator about the operation of all machine systems, monitors compliance with the longitudinal and transverse slopes, the depth of milling across the width of the strip, and the compliance of the working speed with the milling force.

Like any field of knowledge or academic discipline, Rules of the road have a whole system of concepts (or terms). Imagine how difficult it would be to learn material, for example, in mathematics, if such concepts as integral, rational numbers, function, etc. were excluded from the vocabulary of this science.

So traffic rules use in their vocabulary its own - purely traffic rules-shnuyu - terminology. And the lion's share of section 1 of the Rules (the entire paragraph 1.2) is devoted exclusively to the concepts used in the traffic rules.

Before proceeding to a direct analysis of these concepts, let us make one important remark. If we take a quick look at the text of paragraph 1.2, we can conclude that it is an extremely inconvenient way to systematize the material. All terms are in alphabetical order.

And it turns out the following: for example, two similar concepts - "stop" and "parking" - should be considered in parallel. In reality, they turn out to be “divorced” thanks to the alphabetical system of systematization. And the integrity of the perception of information about them is violated, and continuity is lost.

That is why we will analyze not each concept separately, but blocks of concepts united by some related features.

So, in the last article we examined the basic principles of traffic rules. Starting with this article, we begin to study the basic concepts used in traffic rules.

It seems to us that the concept of the road is central in the Rules of the Road. Indeed, the Rules of the Road ...

"Road" - a strip of land or the surface of an artificial structure, equipped or adapted and used for the movement of vehicles. The road includes one or more carriageways, as well as tram tracks, sidewalks, shoulders and dividing lanes, if any.

Consider first the first part of this definition. So, “road” is a strip of land or a surface of an artificial structure that is equipped or adapted and used for the movement of vehicles ...

What does it mean? Very simple. The part of the earth's surface, which has the necessary infrastructure for the organization of traffic on it, is called a road.

For example, in front of you is a city road (more precisely, a road in a village).

And here, please, a country road (or a road outside locality).

However, the road can also be represented by an artificially created surface - a kind of structure (bridge, overpass, overpass). This is also a road.

Do not forget that the road can be temporary, intended for movement during the season or even for a shorter time. For example, a narrow strip laid by a bulldozer or grader in the middle of a snowy field.

It will be expensive only until the spring thaw or the beginning of the next cycle of agricultural work. But right now, she's on the road.

But the second part of the concept of "road" cannot be considered and understood without the involvement of other terms. Judge for yourself. The road includes one or more carriageways, as well as tram tracks, sidewalks, shoulders and dividing lanes, if any.

In other words, for the completeness of the disclosure of the concept of "road" we must analyze a number of terms. And, judging by the second part of the definition, the road has its own structural elements and consists of:

1. The carriageway (or several carriageways);
2. Dividing strip (or several dividing strips) - if any;
3. Roadside - if available;
4. Sidewalks - if available;
5. Tram lines - subject to availability.

Having considered these concepts, we can draw an adequate conclusion about what a road is.

Consider the ROADWAY.

"Carriageway" - an element of the road intended for the movement of trackless vehicles.

And here, let's talk about the confusion that often happens among novice or ignorant drivers. They believe that the road is (roughly speaking) that section of asphalt pavement on which cars move. Such a position is fundamentally wrong, erroneous.

The asphalt pavement section is precisely the CARRIAGE, that is, only the PART of the ROAD, which is intended for the movement of trackless vehicles (everything except trams) along it.

Let's make an intermediate conclusion. A CARRIAGE ROAD is an obligatory, necessary element of the road, which is used exclusively for the movement of off-rail vehicles. Formally (or legally), if there is no roadway, then there is no road itself. Agree, it is quite logical.

Let's continue. The next element of the road is the DIVIDING STRIP.

"Dividing strip" - an element of the road, allocated constructively and (or) using markings 1.2.1, separating adjacent carriageways and not intended for the movement and stopping of vehicles. And again - in order to better understand this concept, we will consider it in detail.

Firstly, "median strip" - an element of the road, ... separating adjacent carriageways.

The main function of the dividing strip is to delimit traffic flows (mainly opposite directions). This is done, for example, to ensure the greatest possible road safety.

After all, the dividing strip makes it minimal to enter the lanes intended for oncoming traffic. That is why the median strip is an obligatory element of the fastest road in the Russian Federation - the motorway.

And here is the most important thing with regard to the dividing lines. By the fact of their presence, they distinguish two or more carriageways on the road.

For example, two carriageways, if there is only one dividing strip.

Or three carriageways, if there are two dividing lanes, etc.

The most representative type of dividing strip is the lawn shown in the figure above, bounded by curbs. This is, so to speak, a textbook example.

This is a constructive version of the dividing strip, that is, designed with the help of a physical structure - a lawn. This type may also include reinforced concrete, metal fences and other physical structures.

But the dividing strip can also be framed logically - with the help of a horizontal one, indicating the edge of the carriageway. This is exactly the same dividing line.

In this regard, a remark needs to be made. Quite often, drivers confuse the dividing strip marked with markings and the double solid marking line (horizontal). Let's try to close this topic once and for all.

You noticed that in the bottom figure, the distance between the white solid lines is equal to the width of any of the lines.

Remember! This is a double solid markup. And in the upper figure, the distance between the white lines exceeds the above value. So, this is the dividing line.

And, finally, one more characteristic of the dividing strip. "Dividing strip" - an element of the road, ... not intended for the movement and stopping of vehicles.

Here, as they say, without options. The dividing strip is not intended for vehicles, but solely for the allocation of adjacent carriageways. That is why it is impossible to move on it or make a stop and parking.

Let's sum up one more preliminary result.

The dividing strip is also an element of the road that divides a single carriageway into several carriageways. It is important to remember that the dividing strip is not intended for movement, stopping and parking of vehicles. Its purpose is different. And it is not at all difficult to guess that the dividing strip is an optional element of the road.

"Side" - an element of the road adjacent directly to the carriageway at the same level with it, differing in the type of coverage or marked out using markings 1.2.1 or 1.2.2, used for driving, stopping and parking in accordance with the Rules.

The curb is also an element of the road. Ask why? It's just that in the vast majority of cases, the roadside is used to stop and park vehicles (and in exceptional cases, to move).

In turn, stopping and parking are modes of using vehicles, which are regulated by Section 12 of the SDA. Therefore, the shoulder - purely logically - should also be an element of the road, bordering on the carriageway.

Very often, the roadside differs from the roadway in the nature of the coating: the roadway is formed with asphalt, and the roadside is formed with gravel, crushed stone, sand, clay, turf, etc.

However, on large or high-speed highways, it is practiced to apply special horizontal markings to the edge of the carriageway and, on the opposite side of which the shoulder begins.

The shoulder is not an obligatory element of the road. So, in settlements, it may simply be absent.

Let's draw a conclusion and on the sidelines. The shoulder is another possible element of the road, which is directly adjacent to the carriageway and serves mainly to stop and park vehicles.

But this is not the end of the road. Another element of it is the sidewalk.

"Pavement" - an element of the road intended for the movement of pedestrians and adjacent to the carriageway or cycle path or separated from them by a lawn.

Here, in principle, everything is clear. However, the traditional question pops up: “Why is the sidewalk part of the road?”. Agree, at first glance, quite a reasonable remark. But this is only at first glance". Let's take a look at the arguments.

First, sidewalks are for pedestrians. And they are road users. It is quite logical that sidewalks are an element of the road.

Secondly, in some cases, vehicles are still allowed to move and park on sidewalks. And although these are very rare moments, but the fact, as they say, is obvious.

It should also be said that the sidewalk is an optional element of the road. For example, outside the settlement it is simply absent. For uselessness. Pedestrians move along the side of the road.

Summarize. Sidewalks are also part of the road that adjoins directly to the carriageway or is separated from it by a lawn.

The last element of the road is TRAMS, which are also not necessary and obligatory parts of the road. By the way, there is a tendency to eliminate trams as a form of public transport. It is both uneconomical and non-ergonomic.

By the way, traffic rules do not qualify tram tracks in any way, noting only that they are part of the road, but do not belong to the carriageway. The driver should be aware of this.

This could be the end of the first block of concepts related to the road. However, it would be appropriate to include here another term - TRAFFIC LANE.

The fact is that the movement of vehicles is carried out on the roadway (we already know this). The carriageway must be divided into traffic lanes.

"Lane" - any of the longitudinal lanes of the carriageway, marked or not marked with markings and having a width sufficient for the movement of cars in one row.

In other words, a traffic lane is an element of the roadway intended for the movement of one vehicle.

However, there are cases when the markings on the roadway have not yet been applied, or when they have worn out and become indistinguishable, or when they are simply covered with snow, sand, a layer of dust or dirt. And, unfortunately, there are no signs.

It turns out that there are no traffic lanes on this roadway?

This is not true. Let's remember the definition: "traffic lane" - any of the longitudinal lanes of the carriageway, marked or not marked with markings ...

And if the traffic lanes on the carriageway are not marked in any way, then, in accordance with the requirements of Section 9 of the Rules, the driver is obliged to independently determine his position on the carriageway, taking into account:

1. The width of the carriageway;
2. vehicle dimensions;
3. required spacing between them.

In other words, the driver is obliged to determine the number of lanes on the roadway "by eye". Sounds like a paradox? Not at all. This is a traffic law requirement. (By the way, we will dwell on this technique in more detail when analyzing Section 9 of the SDA).

Now let's take a concrete example.

How many lanes are on this roadway? Or let's ask the question in a different way: how many vehicles will pass safely in the cross section of the road? That's right, four. Before us is a four-lane two-way road (two lanes in each direction).

Thus, traffic lanes on the carriageway can be marked either visually (using markings or signs) or virtually (by the driver himself, taking into account the characteristics of the carriageway and the dimensions of vehicles).

So, we have examined in sufficient detail the concept of the road and its elements. Let's make a general conclusion.

A road is a part of the earth's land or an artificially created surface (bridge, overpass, overpass, crossing, etc.), which is provided for the movement of vehicles.

The road to includes the carriageway (or carriageways - depending on the presence of a median) divided into traffic lanes, as well as the median lane (or lanes), shoulders, sidewalks and tram tracks, if any.

The article is described in so much detail and competently that it is impossible to convey words of admiration to the author! This is exactly what every independent beginner needs to read! Thank you!

The projection of the axis of the highway on a horizontal plane, with the image of the elements of relief and landscape, is called the plan of the route (the position of the axis of the highway on the ground).

The projection of the axis of the road (on the surface of the carriageway) on a vertical plane passing through the axis itself is called a longitudinal profile.

Cross slope is a term referring to a transverse profile (section by a vertical plane perpendicular to the axis of the road).

Slope - the ratio of the elevation to the foundation. A dimensionless quantity equal to the tangent of the angle between the inclined section and its horizontal projection. It is expressed in ppm ‰ (thousandths).

for small values ​​of α

In order to formulate the requirements for the geometric elements of the axis of the road, we consider the forces acting on the car during its accelerated upward movement:

- resistance to movement on the rise;

- rolling resistance (rolling friction);

- vehicle inertia;

-windage

The movement of the car is possible if the traction balance condition is met:

, where

[H] - traction force developed by the design vehicle

Appendix 03_02

The resistance to movement on the slope i, is determined by the work done by the engine to move the car per unit height. If we take the length of the section, and the excess of its end point over the initial one, then, neglecting all other forces acting on the car, the engine work will be equal to:

[kg] – vehicle weight;

We attribute the work of the engine to move the car to a height , to the length of the section , we get the value of the force necessary to overcome the slope i at each of its points:

Obviously, if the condition is not met, then the movement of the car becomes impossible. Otherwise, neglecting all other forces acting on the car, it is possible to determine the permissible value of the longitudinal slope from the condition of the possibility of movement of the calculated car:

Of course, in the case of real calculations, it is necessary to consider the totality of the action of all resistance forces. In addition, the limit values ​​obtained as a result of such a calculation are not satisfactory in terms of speed and driving comfort. Therefore, it is necessary to introduce some safety factors.

Rolling resistance is caused on a perfectly flat surface by the expenditure of energy to overcome the deformation of pneumatic tires, as well as the elastic and plastic deformations of the pavement. It is logical that the rolling resistance is the sum of the corresponding values ​​for each wheel of the car:

, where

[H] - fractions of gravity attributable to individual wheels;

– corresponding rolling resistance coefficients

Typically, the rolling resistance coefficient is related to the total weight of the car, that is, it is considered that:

Rolling resistance coefficient values ​​vary depending on the material and surface condition of the coating. For asphalt concrete and cement concrete pavements f = 0.01 - 0.02; for a dirt road with roughness f = 0.15. It is logical that the coefficient of rolling resistance, and in fact, the rolling resistance itself in real conditions is a function of evenness.

We will consider the resistance of inertial forces in the context of traction balance exclusively as the inertia of translational motion. However, do not forget that on curved sections in the plan, inertial forces will determine the level of traffic safety, but we will consider this issue separately. In addition, part of the engine power is spent on overcoming the inertia of the rotating parts, which must be taken into account when assessing the real dynamic characteristics of the car. Taking into account the above limitations, the resistance of inertial forces will be expressed by the ratio:

, where

is the relative acceleration of the vehicle;

[m/s2] – translational acceleration of the vehicle

[kg] – vehicle weight;

[m/s 2 ] – free fall acceleration

Air resistance is caused by three reasons:

-pressure of oncoming air on the front of the car;

- friction of air on the side surface of the car;

The power consumption to overcome the resistance of the turbulence of the air jets behind the car, near the wheels and under the body.

According to the laws of aerodynamics, the air resistance will be equal to:

, where

is the drag coefficient of the medium (a dimensionless quantity depending on the shape and shape of the body, as well as on the smoothness of its surface);

[kg / m 3] - air density;

[kg / m 3 ] - coefficient of air resistance, determined experimentally;

[m 2 ] - the area of ​​the projection of the car on a plane perpendicular to the direction of its movement;

[m/s] is the relative speed of the vehicle and the air.

Given the characteristics of the calculated vehicle and the value of the calculated speed, it is possible to determine the values ​​of permissible longitudinal slopes for certain driving conditions. It should be noted that the values ​​of the longitudinal slopes of the road, among other things, determine the cost of fuel during the movement of cars, and, consequently, the transport component of the cost of transportation. Therefore, it is logical to consider the appointment of longitudinal slopes also in the context of the efficiency of transport work.

On difficult sections of roads in mountainous areas, the lengths of long sections with slopes of more than 60 ‰ are limited depending on the height of the section above sea level.

The values ​​of the maximum permissible longitudinal slopes are determined by the value of the calculated speed, therefore, when determining them, the dynamic characteristics of the calculated vehicle were taken into account (the power is not the same for different gears and speeds).

Appendix 03_03

"Requirements for the geometry of the road"

Next, consider the curvilinear sections in the longitudinal profile and the conditions of movement along them. In the case of movement along a convex vertical curve, an inertia force acts on the car, directed from the center of curvature.

In this case, the weight of the car (the force with which it acts on the surface of the coating) is reduced. Neglecting the value of the angle between the vectors of centrifugal force and gravity, we can write that the weight of the car will change (decrease) by an amount equal to the value of the centrifugal force:

, where

[m/s] – vehicle speed;

[m] – vertical curve radius

By reducing the weight of the car, the value of the friction coefficient also decreases. Coefficient of friction: a dimensionless value equal to the ratio of the traction force on the rim of the drive wheel to the proportion of the vehicle's gravity on this wheel at the moment of slipping:

In fact, the coefficient of adhesion characterizes the limiting value of tractive effort, in relation to the force of gravity attributable to a given wheel. With a greater value of traction force, the connection between the surface of the coating and the wheel is lost, slipping begins. (for a/b coatings 0.5)

Assuming the friction coefficient to be a constant value that characterizes only the qualitative state of the pavement surface of the roadway, it is obvious that the maximum traction force (in fact, characterizing the stability of the car) decreases along with the value of the car's weight. This change is proportional to the square of the speed of movement and inversely proportional to the radius of the vertical curve. Therefore, for large values ​​of the calculated speed, from the condition of vehicle stability, it is necessary to introduce large radii of vertical curves.

In the case of a car moving along a concave vertical curve, the centrifugal force, on the contrary, leads to an increase in its weight. It is logical to assume that in this case the stability of the car increases (the maximum possible value of tractive effort increases). But at the same time, the load on the chassis of the car also increases. So, for an estimated speed of 80 km / h, when moving along a concave vertical curve with a radius of 1000 m, the value of the centrifugal force will be:

Appendix 03_04

"Requirements for the geometry of the road"

Inertial forces act on the car and when it moves on a curve in the plan (in the horizontal plane). With a certain combination of speed and radius of curvature, the vehicle may skid or roll over. Therefore, to determine the minimum allowable curve radius in the plan, one should proceed from the value of the design speed.

Consider the case of a car moving along a section of the carriageway with a transverse slope i. Let's write down the sum of the projections of all forces acting on the car, on the axis passing through its center of mass and parallel to the surface of the roadway:

Revealing the value of the centrifugal force and, taking into account the possibility of different directions of the transverse slope, we get:

In order to obtain a relative indicator that characterizes the conditions of movement on the curve in the plan, independent of the mass of the car, we divide the resulting amount by the value of gravity:

The resulting coefficient is called the shear force coefficient. It shows what proportion is the sum of all forces that tend to move the car from the curve for given combinations of radius, speed and cross-slope of the carriageway in relation to the force of gravity acting on the car. Express the value of the radius:

; ; ;

Thus, an expression was obtained to determine the permissible value of the radius of the curve in the plan at a certain value of the design speed. In this case, the driving conditions will be characterized by the coefficient of the transverse force:

-at m< 0,10 – кривая пассажирами не ощущается;

- at m = 0.20 - it is felt and the passenger experiences inconvenience;

- at m = 0.30 - the entrance from the straight section to the curve is felt as a push, tilting the passengers to the side;

- with m > 0.6 - the car may tip over.

So, for an estimated speed of 150 km/h, and a shear force coefficient of 0.15, we get the minimum allowable value of the curve radii in the plan (the transverse slope is 0):

As you can see, the cross slope of the roadway can both help and hinder the stability of cars on a curve. So, in areas where for some reason it is difficult to provide the required minimum allowable value of the radius of the curve, the roadway is given a certain transverse slope with an increase in elevation from the center of the curve. A smooth change in the transverse slope on the approaches to a curved section is called a turn. The transverse slopes of the carriageway on bends vary depending on the radii of the curves. The transition from a gable transverse profile to a single-slope should be carried out on transition curves.

Within the transition curves, there is a smooth change in radius from ∞ at the beginning to the radius of the main (circular curve) at the end. Spiral curves with a circular insert are called compound curves. Composite curves must be designed with a curvature radius of less than 3000 m on roads of technical category I and less than 2000 m for technical categories II-V. Types of transition curves: radioidal spiral, lemniscate, cubic parabola, box curves.

The value of the radius of the curve also determines the visibility distance in the plan. Thus, the minimum allowable radii of curves in the plan are determined from the condition of vehicle stability on the curve and the visibility distance.

The radii of adjacent curves in the plan should not differ by more than 1.3 times (safety factor). A short, straight insertion between two parallel-pointing horizontal curves is not recommended. With a length of less than 100 m, it is recommended to replace both curves with one, larger radius; for a length of 100 - 300 m, it is recommended to replace the direct insert of the transition curve of a larger parameter.

In addition to curved sections in the plan, certain requirements apply to straight sections. The length of straight inserts is limited depending on the technical category and type of relief. So for a highway of the I technical category, the maximum length of a straight line in the plan is 3500 - 5000 m in a flat area.

In other words, the load, both on the chassis of the car and on the driver, increases by almost half. Under such driving conditions, the wear of the undercarriage of the car will increase markedly, and the driving comfort will deteriorate. The driver perceives such road conditions as dangerous and reduces the speed of movement, which leads to a decrease in the capacity of such sections.

The values ​​of the radii of the vertical curves determine the visibility distance in the longitudinal profile. The values ​​of visibility distances for an oncoming vehicle and for a stop are normalized separately. For the corresponding design speeds, these distances should ensure that the driver perceives suddenly emerging obstacles within the carriageway in a timely manner and maneuvers to avoid an accident (emergency braking or avoiding an obstacle). The smallest visibility distance for stopping should ensure the visibility of any objects having a height of 0.2 m or more, located in the middle of the lane, from a height of the eyes of the driver of the car 1.2 m from the surface of the carriageway.

It is quite easy to evaluate the dependence of the radii of vertical curves and visibility distances graphically. To do this, it is necessary through each point of the longitudinal profile, above the line of height marks of the axis of the carriageway (red line), to draw a tangent to the line reflecting the height marks in both directions from the viewpoint. The length of the tangent segments to the touch points will reflect the corresponding visibility distance values.

Thus, the requirements for the allowable values ​​of the radii of vertical curves are determined by the following considerations:

Cars when driving at the estimated speed should not lose controllability and stability on the roadway;

The level of loads caused by inertial forces should not lead to a deterioration in the driver's emotional perception of driving conditions and wear of the vehicle chassis;

- the necessary visibility distance must be ensured.

Application 03_05

"Requirements for the geometry of the road"

Calculation of the width of one lane

The carriageway of the motor road must have a width that ensures the safe movement of vehicles at the estimated speed in one or more lanes. If the width of the carriageway is insufficient, this will necessitate a reduction in speed when cars meet. If an excessive width is assigned, then unjustified funds will be spent on the construction of an expensive coating.

The lane occupied by the width of the carriageway by a moving car is called a traffic lane. The higher the speed of movement, the greater the width of the lane is necessary for the safe movement of vehicles.

The lane width can be determined by the formula:

Then, taking the width of the car (MAZ-511) equal to 2.70 m, we get the lane width: