The main parameters of the bridge are length, height, bridge opening, carrying capacity.Lengthbridge is called the distance between the back faces of its abutments, andtall- distance from the foot of the rail to the low water horizon.holebridge is the clear distance between the inner faces of the abutments of a single-span bridge, or the sum of such distances between all the supports of a multi-span bridge at the level of the calculated water horizon.load capacity bridge is the maximum load that it can withstand while ensuring the safety of train traffic. The parameters of the bridges are determined by the width of the water barrier, fluctuations in the water level, given by the norm of the mass of trains.
Depending on the length, the number of spans, the design and material of the span, the number of tracks and the method of transferring pressure to the supports, bridges are classified as follows:
by number of flights - one-, two- and three-span, etc.;
according to the number of main routes - one-, two- and multi-track;
by span structure - with a ride on the bottom, on top and in the middle;
by material- stone, metal, reinforced concrete, wood;
by lenght- small (up to 25 m), medium (25-100 m), large (100-500 m) and out-of-class (more than 500 m);
according to the method of transferring pressure to the supports (static scheme) - beam, arched, frame, hanging, cable-stayed, combined.
Static Bridge Diagrams
:
a - beam; b - arched; in - frame, d - hanging, d - cable-stayed, R, H - respectively vertical and horizontal reaction of supports
In girder and cable-stayed bridges, the span structure transmits only vertical pressure to all supports, due to which the supports have relatively light structures. In bridges of other static schemes, coastal supports operate under more complex forces, so they are built massive and do not give subsidence.
1 and 2 - superhighway;
3 and 4 - trunk;
5, 6 and 7 - local significance.
4.2 Waterways, depending on the guaranteed (standardized) dimensions of the passage, are divided into sections.
4.3 The class of the section of the waterway on which the construction or reconstruction of bridges is envisaged should be determined in accordance with the main characteristics given in Table 1.
Table 1 - Main characteristics of waterways and transport cargo fleet
| In meters |
|||||
| water class path (section) | Depth of the ship's course perspective | Estimated width Length composition | Estimated surface height ship |
||
| guaranteed- naya | middle navigation tional | shipboard | raft | ||
| 1 - superhighway | St. 3.2 | St. 3.4 | 36/220 or 29/280 | 110/830 or 75/950 | 15,2 |
| 2 - the same | St. 2.5 to 3.2 | St. 2.9 to 3.4 | 36/220 | 75/950 | 13,7 |
| 3 - trunk | St. 1.9 to 2.5 | St. 2.3 to 2.9 | 21/180 | 75/680 | 12,8 |
| 4 - the same | St. 1.5 to 1.9 | St. 1.7 to 2.3 | 16/160 | 50/590 | 10,4 |
| 5 - local value | St. 1.1 to 1.5 | St. 1.3 to 1.7 | 16/160 | 50/590 | 9,6 |
| 6 - the same | Over 0.7 to 1.1 | Over 0.9 to 1.3 | 14/140 | 30/470 | 9,0 |
| 7 - the same | 0.7 or less | 0.6 to 0.9 | 10/100 | 20/300 | 6,6 |
| Notes 1 The table does not show the characteristics of the vessels of the passenger and technical fleet (dredgers, floating cranes, etc.), trains used for the transportation of large-sized and other special equipment, which, when determining the class of the waterway and underbridge dimensions, should be taken into account additionally, based on the specific conditions of the waterway section . 2 The calculated values of the dimensions of the raft convoy are given without taking into account the dimensions of the auxiliary raft tug. |
|||||
If according to the guaranteed and average navigational depths of the ship's course the section is , then it should be attributed to the higher of these classes.
In sections of waterways where guaranteed dimensions of the passage are not established, but which are used or planned to be used in the future by the transport fleet during the full-water period of navigation, the class should be determined by the average navigation depth.
Sections of waterways, on which the use of the transport fleet shown in Table 1 is not expected in the estimated future, but suitable for navigation, should, as a rule, be attributed to the 7th class.
The class of a waterway section, as a rule, cannot be higher than the class of the downstream section. The exceptions are waterways where the increase in guaranteed depth occurs from the bottom upstream or where local traffic is more developed than transit traffic.
Average navigation and guaranteed depths should be determined in accordance with current recommendations for determining the class of inland waterways.
4.4 The outlines and dimensions of the bridge clearances of navigable fixed and drawbridge spans (hereinafter referred to as the bridge clearances), depending on the class of the waterway, must correspond to those indicated in Figures 1 and 2 and in Table 2.
ABCDA and AEFKLDA - bridge clearance contours;
PU - design water level;
Figure 1 - Underbridge clearance of a fixed navigable span of the bridge
DCS - estimated high navigable water level;
PU - design water level;
The total height of the bridge clearance;
The height of the underbridge clearance above the DCS;
Bridge clearance width;
Guaranteed depth of the ship's course for the future;
Amplitude of water level fluctuations between DCS and PU.
The position of navigation marks is conventionally not shown.
Figure 2 - Underbridge dimension of the movable navigable span of the bridge
a) - with the opening of the span;
b) - with a vertical rise of the superstructure
Table 2 - Underbridge dimensions of navigable spans of bridges
| In meters |
|||
| water class path (section) | Underbridge height, not less than | Underbridge width, no less, for overflight |
|
| non-divortable | adjustable |
||
| 1 | 2 | 3 | 4 |
| 1 | 17,0 | 140 | 60 |
| 2 | 15,0 | 140 | 60 |
| 3 | 13,5 | 120 | 50 |
| 4 | 12,0 | 120 | 40 |
| 5 | 10,5 | 100/60 | 30 |
| 6 | 9,5 | 60/40 | - |
| 7 | 7,0 | 40/30 | - |
| Notes 1 The values given in the table are the dimensions of the passage under the navigable spans. 2 The denominator is the width for the second and subsequent navigable spans. 3 The widths indicated in column 4 are given for a drawbridge designed to pass only ships with a high surface height (exceeding the values indicated in table 1). If the draw span is intended for the passage of trains, then its width should be taken in accordance with column 3. |
|||
4.5 The outline of the bridge clearance should be rectangular (corresponding to the contour ABCDA indicated in Figures 1 and 2).
On sections of waterways of the 1st-4th classes for fixed spans of bridges with a curvilinear outline of the lower belt of spans located in cramped conditions (within cities and approaches to them, near transport hubs, on highways ah with complex junctions on the banks and in other justified cases), it is allowed to take the outline of the bridge clearance along the AEFKLDA contour. At the same time, the height and width are set in agreement with the authorities regulating navigation, but not less than 0.7 and 0, respectively,
4.6 In fixed spans, it is allowed to reduce the width of the bridge clearance, m:
In a span intended for the movement of floating facilities only downstream in the absence of water transport on waterways:
| 4th | class | - | before | 100; |
|
| 5th | " | - | " | 80; |
|
| 6th | " | - | " | 40; |
|
| 7th | " | - | " | 30; |
In a span intended for the movement of floating facilities only upstream at an average current velocity during the low-water period exceeding 0.5 m/s, on waterways:
| 1st | class | - | before | 120; |
|
| 2nd | " | - | " | 100; |
|
| 3rd and 4th | " | - | " | 80. |
In this case, the outline of the bridge clearance should only be rectangular.
4.7 The width of the underbridge clearance can be taken less than that indicated in Table 2 if the bridge span completely covers the total width of the waterway with the right-of-way on both sides, which is under the jurisdiction of the river transport authorities.
4.8 For bridges with movable spans, which are designed to pass only ships with a high surface height, the height is set in agreement with the authorities regulating navigation and other interested authorities. At the same time, it should be determined on the basis of the free height of the respective vessels or objects intended for piloting in this navigable passage.
As a rule, bridges consist of superstructures and supports. Span structures serve to absorb loads and transfer them to supports; they may have a roadway, a pedestrian crossing, a pipeline. The supports transfer loads from the superstructures to the base of the bridge.
Superstructures consist of load-bearing structures: beams, trusses, diaphragms (transverse beams) and the roadway slab itself. The static scheme of superstructures can be arch, beam, frame, cable-stayed or combined; it determines the type of bridge by design. Usually spans are straight, but if necessary (for example, during the construction of overpasses and road junctions), they are given a complex shape: spiral, ring, etc.
The superstructures are supported by supports, each of which consists of a foundation and a supporting part. The forms of supports can be very diverse. Intermediate supports are called bulls, coastal - abutments. Abutments serve to connect the bridge to the approach embankments.
Materials for bridges are metal (steel and aluminum alloys), reinforced concrete, concrete, natural stone, tree, ropes.
Bridge diagram - a formula in which the dimensions of the calculated spans are sequentially presented - the distances between the centers of the supporting parts of the span structures. If several consecutive bearings are of the same size, their number is indicated multiplied by the size of each. For example (fictitious "bridge"), bridge diagram 5+3x10+4 m means that the first span of the bridge has an estimated span of 5 meters, the next three - 10 meters each and the fifth - 4 meters.
Bridge deck structure
Draw on what and where is located.
Pavement on the bridge structure. Design. Materials. The purpose of each element. Requirements. (here it is necessary to schematically show the “pie” of pavement on the bridge structure, explain what each element is needed for and the materials from which it is arranged)
A sidewalk is a space reserved for the movement of people.
Vertical and horizontal load on the railing:
8. REGULATIONS FOR THE USE OF ROAD GUARDS AND GUIDE DEVICES
8.1 Road barriers
8.1.1 On roads, streets and bridge structures, road barriers are used that are permitted for operation in the prescribed manner.
on roadsides;
on the lawn, the strip between the sidewalk and the edge of the subgrade, the sidewalk of a city road or street;
on both sides of the carriageway of the bridge structure;
on the dividing strip of a motor road, city road or street, bridge structure.
Dynamic deflection of the fence (hereinafter - deflection) - the largest horizontal displacement of the longitudinal axis of the fence beam in the transverse direction relative to the axis of the undeformed fence (Figure B.25a) when a car hits the fence.
Working width- the maximum dynamic lateral displacement of the car body, the load in it or a fragment of the fence (depending on the installation location of the fence) relative to the front surface of the beam of the undeformed fence (Figure B.25 b).
The fence must meet the requirements for the level of holding capacity (table 11), deflection, working width and minimum height (hereinafter referred to as height).
Table 11
Retention levels
| Retention level | | U1 | | U2 | | U3 | | U4 | | U5 | | U6 | | U7 | | U8 | | U9 | | U10 |
| Level value, kJ, not less than | 130 | 190 | 250 | 300 | 350 | 400 | 450 | 500 | 550 | 600 |
8.1.4 The levels of holding capacity of fences are selected taking into account the degree of complexity of road conditions for sections of roads according to 8.1.5, for bridge structures of roads according to 8.1.6, for city roads, streets and bridge structures in cities according to 8.1.7.
WATER DISCHARGE SYSTEMS. Here you need to schematically show the drainage system from the bridge structure, indicate its components, etc.
In this methodological document, the following terms are used with the corresponding definitions:
1 Expansion joint design: a structural element of the bridge deck that bridges or fills the gap between the spans or between the span and the support, does not prevent their mutual movements, is connected by anchor devices with the supporting structure of the spans and bridge supports and transfers forces to them from the interaction of vehicles , temperature and other factors.
2 Expansion joint edging: structural elements of the expansion joint, edging the contours of mating structures in the gap (road pavement on the structure, the end of the superstructure, the edge of the head part of the support or the cabinet wall of the abutment), anchored in them and designed to absorb forces from the elements blocking the gap and protect bordered structural elements from destruction when exposed to vehicles.
3 Expansion joint filling: Structural element of an expansion joint that fills the gap at the carriageway level.
4 Compensator: structural element of the expansion joint, due to the deformation of which the displacement of the ends of the superstructure is compensated and the tightness of the joints is maintained.
5 Mastic: a mixture of mineral powder (filler) with bitumen or tar in a hot and cold state (base), used to fill temperature (deformation) joints and cracks (crevices). Depending on the base and filler, mastics are distinguished: rubber-bitumen, bitumen-polymer, polymer-bitumen, etc.
6 Drainage: A garment element on the driving surface that quickly drains water from the layers of clothing and consists of a drainage channel, drainage material and drainage tubes.
7 Pavement - a set of all elements located on the slab of the carriageway of superstructures designed to ensure normal conditions and safety for the movement of vehicles and pedestrians, as well as to drain water from the carriageway. Includes roadbed clothing, sidewalks, barriers, drainage, heating and lighting devices, expansion joints and bridge interface with approaches.
Classification of constructions of expansion joints and their main parameters (properties) Classification of KDSh refers only to the class of structural solutions used in bridge structures of highways, and provides for grouping structures (design solutions) according to various specific characteristics. As the main species feature that separates Constructive decisions on the types of construction, a method has been adopted to bridge the gap between the ends of the superstructure or the end of the superstructure and the support.
According to the method of closing the gap, KDSh are divided into the following types:
Open - the gap (seam) is open and water, dirt and various objects freely enter the space between the ends of the span structures (on bridge structures of roads Russian Federation such structures have not found application due to the need for their daily cleaning);
Closed - the gap is closed from above (at the level of the pavement or pavement), and the pavement does not have a gap above the gap;
Filled - the coating and all layers of clothes have a gap above the gap, filled, as a rule, with an elastic element (rubber, mastic ...), due to the deformation of which the movements of the span ends are compensated;
Overlapped - the gap between the ends of the superstructures is blocked by some element (sheet, plate), which changes position (without opening the gap) when the ends of the superstructures move; 6 ODM 218.2.025-2012
Retractable type seam - structural elements have special plates on the supporting parts and enter the space between span structures when moving; are a type of overlapped seam. The designs of expansion joints of closed, filled and overlapped types can have many varieties, of which the most commonly used are shown in tables 1-4 with indication of limit displacements. Limit displacements are the main characteristic of the design of an expansion joint, according to which a preliminary selection of possible for this or that construction of KDSH is carried out. In addition to the longitudinal limiting horizontal displacements in the direction perpendicular to the weld axis, the minimum required parameters of the CVD also include the limiting horizontal transverse (along the weld axis) and vertical displacements of one weld edge relative to the other. The recommended minimum service life of an expansion joint before replacement depends on the design of the expansion joint and the wear of the materials used in the elements of the joint, subjected to loads and destructive factors.
Construction of interfacing with the embankment of a bridge structure
Rice. 2.15. The design of the junction of the bridge with the embankment:
1- asphalt concrete (h = 9 cm); 2 - the base of the carriageway;
3 - drainage layer; 4 - intercepting drainage; 5 - crushed stone;
6 - sand with K f = 4 m/day; 7 - coverage of the roadway on the way;
8 - bed; 9 - adapter plate; 10 - asphalt concrete h = 5 cm
over a layer of rubble h= 10 cm; 11 - side stone; 12 - underslope of black rubble;
13 - a layer of black gravel or a film of non-woven materials or bituminous mastic
The history of the emergence of reinforced concrete structures.
Reinforced concrete(German Stahlbeton) - building composite material, consisting of concrete and steel. Patented in 1867 by Joseph Monnier as a material for making tub for plants.
The height of the underbridge clearance is set for non-navigable rivers from the air-blast to the lowest point of the span should be at least 0.75 m if there is no stump walker on the river, at least 1.5 m if there is a stump walker (exit of whole trees washed off the banks)
For navigable rivers - from the DCS to the lowest point of the span. The value is set depending on the class of the waterway. All navigable rivers according to GOST are divided into 7 classes, with UMV 7kl-35m, 1kl-16m. Extracurricular 20m. for navigable rivers, horizontal erosion of bridge clearances is established. For 1kl waterways and out-of-class waterways, 2 navigable spans can be arranged, with one of the spans being 25-30% larger than the other.
Smaller span for upstream, larger downstream. For overpasses, the height of the underbridge clearance is set:
1. At the intersection of a / d - the distance from the lowest point of the span to the mark of the axis of the intersected a / d. I-IIIcat 5m, others 4.5m.
2. When crossing the railway - the distance to the level of the rail head. 5.9 m if the railway is not electrified, and the bridge being crossed is located outside the station tracks, also when the bridge being crossed is located within the station tracks - 6.1 m.
3. When crossing electrified railways, respectively 6.0 and 6.3m
4. For viaducts and trestle bridges, the height of the underbridge clearance is not standardized.
17. Types of artificial structures on roads
The route of the road, passing through the terrain, encounters various obstacles on its way: rivers, streams, ravines, mountain ranges, hollows, dry valleys. To pass the road through such obstacles, bridges, tunnels, culverts and other artificial structures are built, which are responsible and expensive elements of the road. The simplest kind road artificial structures - culverts under embankments, which serve to pass small permanent or temporary watercourses under the subgrade of the road. An essential feature of the pipe is the continuity of the subgrade above it. Therefore, cars passing over the pipe do not experience any changes in driving conditions.
Bridges are structures blocking an obstacle and interrupting the z.p. roads. Driving on this section occurs according to the design of the bridge.
Tunnels are used to lead the road through the thickness of the mountain range, and in cities - to pass underground streets and pedestrian crossings. There are cases of constructing underwater tunnels under rivers, sea bays and straits. A large number of complex and expensive artificial structures are usually required on mountain roads. In addition to tunnels, galleries have to be built to protect the road from stone and snow avalanches, as well as balconies and retaining walls. The complex of structures arranged to cross the road of the river is called bridge crossings. It consists of: a bridge, approaches to it, regulatory and bank protection structures.
The underbridge clearance is the limiting, normal to the direction of the flow, outline of the boundaries of the space in the span of the bridge, which must remain free for the unhindered passage of ships and rafts and into which no elements of the bridge or devices located on it should protrude.
The number of navigable spans in the bridge should, as a rule, be at least two: one for platoon navigation and one for floating navigation. One navigable span is allowed only in single-span bridges or on condition that a second span cannot be placed due to the insufficient width of the river bed. A navigable span can only be considered active if, over its entire width, ships can navigate even at the lowest water level, and at any point of the span, the depth required by the class of the waterway must be ensured.
The dimensions of navigable spans may be unequal. The spans for rafting navigation are accepted somewhat more than for platoon navigation. This is done because the vessels going downstream, due to the increase in the speed of the water near the bridge, acquire yaw, their control becomes more difficult, and there is a danger of ships piled up on the bridge supports.
If, for structural or architectural reasons, both navigable spans are assumed to be the same, then their size should correspond to the largest of the two required by the standards. The width of the navigable span can be somewhat reduced only for bridges across narrow shipping channels, but on condition that the span covers not only the entire channel, but also towpaths intended for coastal traction of ships.
The height of the calculated navigable level must satisfy the following basic requirement - with a high flood with a certain given probability of exceeding the difficulty of navigation under the bridge, no more than a specified number of days can be observed.
The estimated navigable level for non-locked rivers is determined in accordance with GOST 26775-85 as follows. According to the table, the probability of exceeding the design flood is set and the flood mark is set according to the probability cell, where the marks of the observed floods are plotted according to their empirical probability, which is determined for the members of the ranked series of maximum levels by the formula.
Having determined the calculated flood level from the probability interval, the average duration of navigation in days for all the years of observations is also established. It is allowed that during the flood with the probability of exceeding the calculated navigational level it is allowed to be exceeded for several days, and the permissible duration of the excess is determined by the formula.
To establish the estimated navigable level, a graph of daily levels is built in the calculation year and this level is plotted on it in such a way that levels higher than it are observed for no more than a day.
For rivers with rapidly rising and falling floods, the calculated navigable level is significantly lower than the flood peak in the reference year. Conversely, for rivers characterized by long standing high levels, the difference between the highest level and the calculated navigable level will be negligible.
The floodplain embankment at the junction with the bridge ends with a cone. The connection of the embankment with the bridge can be carried out in various ways. The best of them from the point of view of the unhindered passage of the water flow is the device of a heap abutment, when the flow flows around the fortified surface of the earthen cone, and the coastal support does not come into contact with water.
If the device of the reinforced cone does not provide a smooth supply of the floodplain flow to the opening of the bridge, and floodplain jet guide structures are included in the bridge crossing, then they must adjoin the cone in such a way that the flow smoothly flows around the river slope of the structure, and not the cone. In this case, the crest of the jet-directing dam, located at the same level as the berms of the high embankment near the bridge, is connected with them by smooth curves - platforms that allow transporting repair materials to the dam. In addition, they provide for driving along the crest of the dam under the bridge, if this is not impeded by the height of the last span of the bridge.
The width of the floodplain embankment on top is assigned in accordance with the category of the road, and the steepness of the slopes, depending on the height of the embankment and its working conditions.
The above-water part of the high embankment on the rise to the bridge is designed as an ordinary road embankment. A slope washed by water is designed no steeper than for every 6-8 m of height. Dry and washed slopes are connected by a horizontal platform (berm) 3 m wide, arranged at the level of a low floodplain embankment. The device of the berm provides surcharge of the lower part of the slope of the embankment and increases its stability. Berms are also used to place repair materials in case of damage to the slope fortifications during floods and to transport repair materials to the control structures near the bridge. When designing high floodplain embankments, it is necessary to check the stability of the slopes and their settlement by calculation.
The slopes of low embankments, washed almost at the entire height, are designed with a steepness of no more than 1: 2, starting directly from the edge, with laying for every 6-8 m of height.
INTRODUCTION
The purpose of the calculation and graphic work “Determining the underbridge clearance” is to consolidate the theoretical knowledge gained by students in the study of the section “Navigation equipment” of the course “Inland waterway navigation”.
The guidelines set out the content of the work and the procedure for its implementation. Calculations are made by students individually. Settlement and graphic work is drawn up in the form of an explanatory note in accordance with the requirements of the ESKD and must contain necessary calculations and graphic materials.
The methodological instructions are compiled in accordance with the program of the discipline “Inland waterway navigation” and are intended for students studying at the navigation faculty in the specialty 240200 “Navigation”.
The guidelines provide basic information about the bridge clearances, their dependence on fluctuations in water levels and the class of the waterway, the designation of bridge clearances and their sizes with navigational signs.
There are dozens of bridges on inland waterways, the movement under which is fraught with difficulties and often leads to accidents, including as a result of errors in assessing the height of the bridge clearances.
Performance practical work will allow students to get acquainted with the basic principles of determining the size of underbridge clearances, assess their dependence on the hydrological characteristics and class of the river, compare the standard and actual dimensions of underbridge clearances.
CALCULATION AND GRAPHIC WORK
Determining the height of the bridge clearance
Goal of the work: according to the observation of water levels at the hydrological post, determine the mark of the estimated navigable level, find the height of the underbridge clearance from the estimated navigable, design and working water levels.
Initial data: according to the variant (according to the record book 12211) we have variant No. 11
initial data for calculating the underbridge clearance
table number 1
From table No. 2, we select the classification of waterways for bridge clearances. Since, according to the instructions, the depth of the ship's passage is 4 meters, we have that class No. I superhighway
Table number 2
Classification of waterways for bridge clearances
Table #3
The values of the coefficients a and K
From table No. 3, according to the data, we select the value of the coefficients a and K And we see that the coefficient a=2 ,a K=5
We calculate the serial number of the billing year using the formula:
N= 0.01*a*(n+1) we have a=2, n+1=52+1=53 hence N=0.01*2*53=1.06
Round to the nearest integer N=1
The maximum levels of the spring flood of the river for 1950 - 2001
Since N=1, then the accounting year is accepted No. 1= 1991.
We build a graph for the points of a given year
Daily water levels at the hydrological post
during physical navigation
Higher - 1046 16.06 Lower summer - 403 26.09 129
We consider the duration t of standing water levels
The maximum water level of the reference year is not the reference navigable one. It is assumed that during t days the water levels this year may be above the calculated navigable level. The duration t of their standing depends on the class of the waterway.
Permissible for the class of the waterway, the duration t of standing water levels that were above the calculated navigable level in the calculation year is determined by the formula
t = 0.01 K m,
where m is the duration of physical navigation (the period of ice-free standing of the river) in the reference year, days;
K - coefficient taken according to Table 3
We have t \u003d 0.01 * 5 * 129 \u003d 6.45 rounded to the nearest integer \u003d 6 days
Based on the data of observations of water levels in the reference year, a graph of their fluctuations is constructed. According to the schedule, the level is set, above which during t days there were more than high levels spring flood. This level is taken as the design navigable level (CSL) of water. On reservoirs, the level of the DCS is taken at least 0.5 m above the level of the normal retaining level of the FSL.
The estimated navigable water level is applied indelibly
white paint or fluorescent enamel on the supports of the shipping
bridge span in the form of a horizontal strip 0.3 - 0.5 m wide.
The position of the DCS corresponds to the upper edge of the horizontal strip
On the graph we find DCS = 970 mm.
According to the schedule below, select the project level:
Since, according to the assignment, the security of the design level = 99,5%
Zpu \u003d 322.22 \u003d 322 cm.
Underbridge clearance values
Since we have class “I”, then H psu = 16.0 m., span width B = 140 m.
Hn = 16.0 meters
We calculate the excess over the constructive:
H \u003d 16.0 + 3 \u003d 19.0 meters
The height of the bridge clearance from the design level is determined by the formula
H PU = H FACT + (Z DCS - Z PU),
where Z DCS - mark of the estimated navigation level;
Z PU - design level mark.
H PU \u003d H FACT + (Z DCS - Z PU) \u003d 16 + (970-322) \u003d 16 + 648 \u003d 22.48 \u003d 22.5 meters
The height of the bridge clearance from the working level is determined by the formula
H P \u003d H P - (Z RU - Z PU),
where Z RU is the mark of the working water level.
H P \u003d H P - (Z RU - Z PU) \u003d 22.5-(600-322) \u003d 19.72 \u003d 19.7 meters.
The constructive (actual) height of the underbridge clearance H, counted from the DCS, may exceed the standard height. It is determined by the design of the bridge structure and the position of the axis and edges of the navigation channel in the navigable span.
After the construction of the bridge, the height of its underbridge clearance in each navigable span is indicated using the "Indicator of the height of the underbridge clearance and the edges of the ship's passage in the navigable spans of bridges" - a navigation sign consisting of one or more square boards and green lights located on both supports of the span or span bridge construction.
The number of shields and lights placed on the supports or the superstructure of the bridge, depending on the height of the underbridge clearance.
The exact value of the height of the underbridge clearance from the DCS is shown in the form of numbers on the information sign "Observe the free clearance!" Installed on the support or span of the navigable span of the bridge, and is also given on the sheets of maps of inland waterways and atlases of the Unified Deep Water System.
Bridge height designations
| Bridge clearance height | Sign color depending on the background | Green lights on the left bank and right bank parts of the span | |
| Green - for a light background | White - for a dark background | ||
| Height of navigable span up to 10 m | |||
| The same over 10 to 13 m | |||
| The same St. 13 to 16 m | |||
| The same over 16 m |
For most of the navigation, the operating (actual) water level is below the DCS. This can be determined by stripes on the bridge abutments showing the position of the DCS. It is difficult to determine the exact height of the underbridge clearance from a specific working water level due to the absence of a mark of the estimated navigable level on the maps and in the navigation descriptions. At present, to eliminate this shortcoming, on maps and atlases, the height of the underbridge clearance from the calculated navigable and design level, the mark of which is always given in navigational descriptions, is given.
The mark of the working water level above zero of the chart of the hydrological station or directly the value of the excess of the working level over the design level as of 8 o'clock in the morning daily during the navigation period is brought to the attention of navigators using waybills and radio bulletins.
When moving under bridges located in the downstream of a hydroelectric power station, where the change in water levels during the day can reach several meters, boatmasters are required to request the height of the bridge clearance at the time the vessel passes under the bridge from the traffic controller of the waterways and shipping area.
INTRODUCTION ................................................ ..................................................
GOAL OF THE WORK................................................ ...............................................
INITIAL DATA................................................ ...............................
METHOD FOR DETERMINING THE HEIGHT OF THE BRIDGE