Railway sleepers are the most important structural element of the corresponding highway. The stability of infrastructure directly depends on their quality. In Russia, wooden and reinforced concrete structures are used. In relation to them, a number of the most important standards that determine the size are established. What is their specificity?
Classification of wooden sleepers by type
The dimensions of the sleepers made of wood, in accordance with accepted state standards, should correlate with its type. There are several reasons for the classification of the considered element of the railway track.
Among the most common - appointment. So, sleepers are divided into those designed for:
- the main tracks of 1st, 2nd class or 3rd, provided that their carrying capacity exceeds 5 million tons / km per year, or operated at train speeds exceeding 100 km / h;
- the main tracks of classes 3 and 4, access roads (with intensive work), sorting, and also pick-up and drop-offs - at stations;
- any paths that belong to the 5th grade, including the station, classified as inactive, as well as others, which are characterized by a shunting-and-export type of movement.
These types of paths are built using, respectively, I, II and III types of sleepers. In relation to them, thus, standardized indicators are established.
Humidity factor
The actual size of the railway sleepers made of wood may depend on the moisture level of the material. What does it mean? The fact is that the corresponding values are relevant for humidity not exceeding 22%. If this indicator is greater than the specified value, then the dimensions of the sleepers should be considered taking into account the necessary allowances for drying. Its value depends on the species of wood - coniferous or deciduous. A similar requirement has also been established for cross-sections of composite sleepers.
Permissible deviations of the dimensions of composite sleepers
The size of the sleepers may deviate from the norms fixed in state standards, within acceptable limits. Regarding the length - it is 20 mm, thickness - 5 mm. There are also permissible deviations correlated with the width of the plates, the height of the sides, the distance between the bolts, and also their vertical deviation from the axis of the sleepers.
Standardized sizes of wooden sleepers
Let us now consider, in fact, what sizes of wooden sleepers (railway) can be, depending on the type.
As for the elements of type I railroad tracks, the values should be as follows:
- thickness - 180 mm (tolerance of 5 mm is permissible);
- height of sawn sides - 150 mm;
- the width of the upper layer is 180-210 mm;
- the width of the lower layer is 250 mm (a deviation of 5 mm is permissible);
- length - 2750 mm (adjustment within 20 mm is allowed).
Regarding type II sleepers, its dimensions should meet the following criteria:
- thickness - 160 mm (tolerance of 5 mm is permissible);
- height of sawn sides - 130 mm;
- the width of the upper layer is 180-210 mm;
- the width of the lower layer is 230 mm (a deviation of 5 mm is allowed);
- length - 2750 mm (change within 20 mm is allowed).
In turn, type III sleepers should correspond to the following indicators:
- thickness - 150 mm (deviation of 5 mm is allowed);
- height of sawn sides - 105 mm;
- the width of the upper layer is 140-190 mm;
- width of the lower layer - 230 mm (deviation of 5 mm is allowed);
- length - 2750 mm (adjustment within 20 mm is allowed).
So, we examined the requirements for the size of wooden railway sleepers, which are established by state standards. But in the structure of the railway track there is another important element of wood, used along with sleepers - transfer bars. We examine, in turn, the standards that are set by the state in relation to their size.
Dimensions of the transverse bars: criteria
Like the dimensions of the sleepers, the corresponding figures for the bars are determined by their type. There are also several reasons for the classification of the considered element of the railway track. Among the main ones, as in the case when the dimensions of the sleepers are determined, is the purpose.
So, the bars can be used:
- on the main tracks of Class 1, Class 2 or Class 3, characterized by a cargo intensity exceeding 50 million tons / km per year, as well as a train speed of more than 100 km / h;
- on the main tracks belonging to classes 2, 3 and 4, access (with intensive work), as well as sorting and pick-up that are present at the stations;
- on tracks related to class 5, including station tracks, classified as inactive access roads and others, characterized by a shunting-and-export type of movement.
The indicated paths correspond to types I, II and III of the transverse bars.
As is the case with sleepers, an indicator of humidity matters. So, the standardized dimensions of the transverse bars, characterized by a moisture index of more than 22%, should be considered taking into account the necessary allowance for drying. As in the case of the standards determining the dimensions of the sleepers, in this case it matters what kind of wood is used to make the timber - hardwood or coniferous. In the first case, the necessary criteria are contained in GOST 6782.1-75, in the second - the provisions of GOST 6782.2.-75 are used.
We will study, as in the case when we examined wooden sleepers, the dimensions of the bars in relation to their type.
Sizes of transfer bars by type
If we are talking about bars of type I, then their characteristics should correspond to the following values:
- thickness -180 mm (adjustment within 5 mm is allowed);
- the width of the upper layer is 220 mm (widened), 200 mm (wide);
- width of the lower layer - 260 mm;
- height of sawn side - 150 mm.
- the width of the beam along the non-sawn elements - 300 mm;
Bars of type II should have the following characteristics:
- thickness -160 mm (deviation within 5 mm is allowed);
- the width of the upper layer 220 mm (widened), - 175 mm (normal);
- width of the lower layer - 250 mm;
- height of the sawn side - 130 mm.
- the width of the beam along the non-sawn elements - 280 mm;
The following standards are set for type III beams:
- thickness - 160 mm (deviation within 5 mm is allowed);
- the width of the upper layer is 200 mm (wide), 175 mm (normal);
- width of the lower layer - 230 mm;
- height of the sawn side - 130 mm;
- the width of the beam along the non-sawn elements - 260 mm.
Bars Length: Range
But what are the indicators of the length of the beam? In contrast to the standards governing the size of wooden (railway) ties, when all values depend on the type of the corresponding element, they imply a fairly strict compliance with the established standards, in the case of beams - length criteria are common for all their types. Moreover, the standards do not set a specific indicator, but an interval of 3 to 5.5 meters with a gradation of 0.25 m with permitted deviations within 20 mm.
Bridge bars: specifics of standardization
So, we examined what are the standards governing the dimensions of wooden sleepers (railway) and complementing it in the structure of railway beams. But there is one more important component of the corresponding highways. We are talking about bridge bars. Just as the size of railway sleepers is regulated, this indicator for the considered component of railroad tracks is also fixed in state standards. We will study this specificity in more detail.
The material for the manufacture of bridge beams is wood. Their size is correlated with one parameter - the size of the cross section, as well as acceptable deviation indicators. The main requirement for the bars is a rectangular shape. Corresponding elements of highways are with a section:
- 220 by 240 mm;
- 220 by 260 mm.
The bridge bars of both types, however, should have the same length - 3250 mm. But in terms of standardization of marginal deviations, indicators can vary. So, for bars with a section of 220 by 240 mm, the maximum deviation can be: minus 2 mm (in thickness), 15 mm (in length). Regarding the second type of railway elements, the indicators are different. Thus, thickness adjustments for bars with a section of 220 by 260 mm are not provided, as well as in length, but in width, the corresponding value that is established in the standard is 3 mm.
It can be noted that, in agreement with the customer, bars with other sections - 220 by 280 and 240 by 300 mm, having a length of 4.2 m can be made.
As is the case with the standards governing the size of wooden (railway) sleepers, the length of the bridge bars is set for products within a certain humidity level. In this case, 20%. If the bridge bars will have greater humidity, it is necessary to consider the size requirements taking into account the necessary allowances for shrinkage - in accordance with GOST 6782.1-75.
Reinforced concrete sleepers: classification
Reinforced concrete can be an alternative to wooden sleepers. These products are used on trunk routes. Belong to the category of prestressed. They are involved in laying rail types P75, P65, as well as P50. There are many reasons for the classification of reinforced concrete sleepers:
- by type of fastening with rails;
- according to the type of prestressed reinforcement;
- by electrical insulation characteristics;
- according to the level of workmanship.
In this case, we are interested in the first criterion - the method by which reinforced concrete sleepers are attached to the rails. The dimensions of the product and its other most important characteristics are determined precisely on the basis of the characteristics of the corresponding mechanism. So, depending on the type of fastening to the rails, sleepers are:
- type 1, designed for separate fastening using bolts by fixing the lining on the sleepers;
- type 2, intended for inseparable fastening using bolts by attaching not only the lining, but also the rail to the railroad tie;
- type 3, designed for inseparable fastening using bolts by directly attaching to the rail tie.
Reinforced concrete sleepers: dimensions and other parameters
The most important criterion that determines the required parameters of reinforced concrete sleepers is their classification as one of the above types.
So, if we are talking about a sleeper, classified as 1, then it should have the following characteristics:
- the required distance between the stop edges - 2016 mm;
- the distance between the corresponding edges of one end of the product is 406 mm;
- the height of the product in the rail section - 193 mm;
- the height of the product in the middle section is 145 mm.
Sleepers of type 2 should have the following characteristics:
- distance separating the stop edges - 2016 mm;
- the distance between the corresponding edges of one end of the product is 406 mm;
- the height of the product in the rail section - 193 mm;
- the height of the product in the middle section is 145 mm.
The sleeper, classified as 3, must meet the following parameters:
- distance separating the stop edges - 1966 mm;
- the distance between the corresponding edges of one end of the product is 359 mm;
- height in the rail section - 193 mm;
- height in the middle section - 145 mm.
These are the main characteristics that, in accordance with state standards, reinforced concrete sleepers should have. Its dimensions in terms of length and width are most often fixed - 2700 and 300 mm, respectively. Deviations comparable to those recorded in relation to wooden products are not provided for in reinforced concrete elements in state standards. The size of the railway sleepers of the corresponding type does not imply variability in relation to humidity and other environmental factors.
Wooden and reinforced concrete sleepers: general points and key differences
What other fundamental differences can be noted between reinforced concrete and wooden elements? The first thing that makes the sleepers so different is the size. Weight is also a significant criterion for the dissimilarity of the respective products. The indicator for wooden sleepers is about 80-85 kg, reinforced concrete - about 270 kg. The scope of both those and others does not differ so much. Wooden sleepers, the dimensions of which we examined in the first place? historically preceded by reinforced concrete, but still have not lost their relevance. Moreover, they have a number of major advantages - low cost, ease of transportation, replacement and transportation, and resistance to overloads.