Road engineering survey lofting is to find the road

jd is where the extension lines of the straight segments on both sides of the curve intersect. Note that curves are not only circular curves, but also spiral curves.

The construction pay-off should be closely combined with the process, such as when the roadbed is filled, you can only nail the pile, because anyway, it is necessary to fill wider, and the accuracy is not too high. Entering the road structure construction, there must be side and middle piles. The elevation on the pile should be reviewed during construction.

Your problem is more complicated, you go and buy a book on highway surveying, you want to know, there are all in it.

Not necessarily, when the measurement drawings are handed over, you will be given the overall circuit diagram of the horizontal curve **vertical curve**, and the cross-section drawing, and the cross-section drawing will have a design line (this will also have a text logo) This is the line you wrote.

After finding the design line, "+" is the right "-" is the left, and you can release your line range according to the cross-sectional drawing.

The intersection point is the turning point of the line, so not only the curve has the intersection point coordinates, the intersection point alone can not determine the zy, the yz point because it is impossible to determine his other parameters such as ls, a and can not determine whether he is a complete curve, etc., but some ** he will give directly, or directly in the mobile phone surveyor directly write the complete flat curve and find the zy, yz mileage to calculate the coordinates.

The pile-by-pile coordinates are the design line coordinates, and the direction of the line and the length of the line cannot be determined without the design line coordinates.

The road lofting is not just in the road, as well as the direction of the road, but also to record the height difference of the top layer, there is a slope ratio in the cross-sectional drawing, but also according to the height difference to adjust the width of the line, to the design line to both sides of the radiation to both sides, the greater the number on the right, the smaller the number on the left, the middle is 0, want to determine the width of the road, see the design drawing.

After the surveyor finishes the line and the on-site plumber has handed over the bottom, the constructor can only carry out the construction.

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1. Control measurement: according to the needs of road engineering, plane control measurement and elevation control measurement are carried out;

2. Topographic map surveying and mapping: according to the design needs, field survey the strip topographic map near the road;

3. Centerline measurement: measure the location of the road in the field according to the design requirements;

4. Longitudinal and cross-sectional map surveying and mapping: determine the height and fluctuation of the ground in the direction of the road centerline and perpendicular to the centerline, and draw the longitudinal and cross-sectional maps;

5. Construction survey: according to the design requirements and construction schedule, various pile points are staked out in time as the construction basis.

Cartesian coordinate method (tangent pivot method).

Cartesian coordinate lofting method is a method of lofting points by using the coordinate increment between points and their Cartesian relationships.

The starting point of the curve zy or the end point yz is the coordinate origin, the tangent is the x-axis, and the radius of the origin is the y-axis, according to each on the curve.

The coordinates of the point (x,y) are measured. Along the tangent direction, start from ZY or YZ and measure the x value with a tape measure to obtain the vertical footpoint; Measure the Y value in the direction of the perpendicular line at each perpendicular foot point, and the curve point can be determined. When measuring and setting, the chord length of each point can be measured and checked.

Polar coordinate method (declination method).

Polar coordinate lofting method is a method of lofting by using the relationship between the side length and angle between the points, which is to determine the position of the point pi by the chord tangent angle i and chord length ci between the beginning of the curve zy or the end point yz to any point pi of the curve. This method has check, high accuracy and strong applicability, but the error accumulates, so it is necessary to pay attention to frequent verification when measuring and designing, so it is used in mountainous areas.

Total station coordinate method.

High-grade highways are commonly used with total stations for coordinate centerline lofting, and total stations are one of the main instruments for modern high-grade highway surveying.

First, it is an instrument that integrates infrared rangefinder and electronic theodolite, has the dual function of ranging and angle measurement, and can save time and labor by replacing theodolite for measurement and lofting, and is not affected by terrain and ground obstacles, and the measurement accuracy is high. The total station is used to measure and set the middle line of the highway on paper, and the coordinates of each middle pile are calculated accordingly, and then the line is laid out on the spot. The total station coordinate method lofting is a method of using point design coordinates to carry out point lofting with total station measurement technology.

The main points of the lofting technology of the total station coordinate method, that is, the use of the whole station measurement technology to measure the initial estimate of the point, and compare the directly obtained point coordinates with the design point coordinates, and if the two are equal, the initial estimate point is determined to be the measured point. Generally, the total station or GPS receiver has the function of measuring and setting the whole station coordinate method.

The differences between the two are as follows:1. According to the query of Daoke Baba data, the definition is different: road lofting is to loft the center line and edge line of the road and other elements to the ground through specific tools before construction on the ground.

Point lofting is the placement of some specific points on the ground by specific tools to determine the position and direction of the building on the ground.

2. Different application scenarios: road lofting is mainly used in large-scale infrastructure construction such as roads and squares, and is used to determine the center line and edge line of the road. Point lofting is used in the construction of buildings, determining the position and orientation of buildings on the ground.

3. Different tools and methods: road lofting uses simple tools such as steel tape measure, white powder, iron bucket sail pile to pull a straight line or draw an arc on the ground to complete the differential pin carrying. Point lofting requires the use of high-precision tools such as electronic theodolites and laser measuring instruments, which can be done by measuring the latitude and longitude coordinates of the point or laser measurement.

Are you doing construction or supervision?

Theoretically, all the materials and machinery and equipment must be tested, and the main materials must be supervised to witness sampling, among which pipelines, foundations, trenches, etc. also need to be tested by concealed engineering, that is, the buried backfill must be tested before entering the next step. As for the number of samples, there are norms, so take a good look at them yourself.

You can make a pay-off record of which materials are used in the construction process, and you have to do experiments.

1. The design institute will hand over GPS points, elevation points, ask for curve elements, and vertical curve elements. (Conditional retest GPS).

2. The inspection of the instrument (go to a qualified instrument verification agency, there is a verification report) The total station, level, and tower ruler are all sent.

3. Review drawing structures, elevations, simple mathematical calculations.

4. Select the position of the wire point and bury the wire point (there is a cross at the head of the reinforcement, and the concrete is buried). Start measuring the traverse (measuring the horizontal angle, calculating the traverse coordinates for the distance adjustment), leveling points (you know).

5. The results of the level adjustment meet the specifications and are submitted to the supervisor for signature.

6 Begin to prepare for construction surveys.