Adjustment of closing error by bowditch method

In a self-closing loop, the closing angle may be turned either onto a line within the loop, or onto a line on a previous section of the traverse leading into the loop.

adjustment of closing error by bowditch method

Refer to Traverse Types for diagrams of possible traverse configurations. Any traverse, or a new section which does not commence at a point fixed in a previous section within the same set of data, must have at least one point the first instrument station specified as a fixed point refer to the heading Fixed Points under Enter Points and also close onto a fixed point in order that the section be able to be adjusted; if the start point is not fixed or held fixed from a previous traverse section the traverse will still compute but cannot be adjusted.

Subsequent traverse sections within the same set of data, which commence at points either traverse stations or side-shot points, and either adjusted or not computed in any previous traverse section, do not require that their start points be specified as fixed; in fact, the points should not be fixed if they are 'adjustable' points, as fixing will upset prior traverse adjustment. When the start of a new traverse section is detected by the software, all points prior to the new start are held as fixed for the purpose of allowing the adjustment if necessary of subsequent sections - i.

However, in order to distribute the misclose more in keeping with the anticipated variable reliability of angle observations over lines of differing lengths, the amount of misclose adjustment applied to each angle is proportional to the sum of the inverse lengths of the backsight and foresight lines:. The current traverse section is re-run, applying the required correction to each traverse angle.

Angles observed to side points are not subject to adjustment. Enclosed area - If a traverse section is adjusted, a value will be calculated for the enclosed area. If the traverse is not a loop that closes back to the start, a closure back to the start is calculated to obtain the area - in such a case, Invalid if lines cross is printed in the Traverse Summary following the area value to indicate that the area relies upon the assumption that it is a valid enclosure.

If the closing line or any other traverse line crosses over the traverse route, the area computed will be invalid. Note : No variation to the method of linear adjustment is made for traverses computed on spheroid - it is considered that the method described is adequate for engineering-type surveys.

If a more rigorous adjustment is required, then the Least-Squares Network adjustment is recommended.A Traverse consists of a series of related points or stations, which when connected by angular and linear values form a framework.

What Is Traversing in Surveying | Types | Method | Definition

The Purpose of a traverse surveys is to control subsequent detail, i. Fixing of specific points to which details can be related.

The accuracy of the control survey must be superior to that of the subsidiary survey. When a series of connected lines form a closed circuit, i. When the finishing point coincides with the starting point, then it is called a closed traverse. These closed traverse surveys have many applications like fixing the boundaries of ponds, forests, etc.

In the excel file that opens, enable macros by clicking the Enable Content button. Based on the input that you have, that is, Quadrantal Bearings or Whole Circle Bearings, you can enter data in the appropriate sheet.

The QB values are automatically seen in grey coloured cells which can be further used as input for traverse correction. Enter Line and Length details. Note : If there is an error in the data, the respective data will be highlighted in red text.

If you want traverse correction based on the Bowditch Method, click the Bowditch Button. The BowditchAdj Sheet opens, with corrected coordinates based on Bowditch rule. The TransitAdj Sheet opens, with corrected coordinates based on Transit rule. It is to be noted that the field data is to be entered in the TransitAdj spreadsheet and not in the field data spreadsheet.

Software for Closed Traverse Correction — Excel Solution A Traverse consists of a series of related points or stations, which when connected by angular and linear values form a framework.

Closed Traverse: When a series of connected lines form a closed circuit, i. To know more about Traverse Correction Procedure, Click the link below. How to use the Closed Traverse Correction Module? Click on Home Sheet and enter the Computation Settings. To do so, open the Conversions Sheet. Enter the WCB data as shown.

Click the Convert button to obtain QB Values. Click the Validate button to validate the data. Click Ok and Correct the data.A Traverse consists of series of related points or stations, which when connected by angular and linear values form a framework. The Purpose of a traverse surveys is to control subsequent detail, i. Fixing of specific points to which details can be relates.

The accuracy of the control survey must be superior to that of the subsidiary survey. When a series of connected lines form a closed circuit, i. When the finishing point coincides with the starting point, then it is called as a closed traverse. These closed traverse surveys have many applications like fixing the boundaries of ponds, forests etc.

Present techniques used in traversing using total station as an open traverse. The steps are as described below. GPS pair points are fixed at a convenient distance, approximately about 3 to 5km.

Care has to be taken that the pair of GPS points is fixed at a reliable distance at least 60m is advised for better results and on good monuments. These points are fixed in such a way that they are clearly inter visible and should cater for placing the total station firmly on the GPS stations. Total station is to be checked for its calibration, prism constants for the prisms to be set in the instrument to avoid errors. Total station is then used to conduct the traverse between the GPS points.

adjustment of closing error by bowditch method

This type of traverse ensures that the survey is started from a known pair of points and is closed on known pair of points. Care has to be taken that the last bearing is also taken for correcting the Adjustment.

There are several methods to correct the traverse adjustments. However, in most of the cases Bowditch rule is considered to bethe most reliable. The other methods like transit method, Crandall method, Least Square Methods are used very rarely.

The most accurate method which is known as a adjustment correction by the least square method is used when the accuracy required is very high. This method finds itself applicable in the projects like tunnel works and works warranting for a higher the accuracy.

To know more about the software for Traverse Corrections, Please click the links below. This method is widely used for Closed and open traverses.

Software for Traverse Correction in CAD Package

Open Traverses means that the starting and closing station is fixed with known Co-ordinates. Fixing up of known co-ordinates is generally done by using DGPS.

adjustment of closing error by bowditch method

A Traverse is run between these two fixed points and then for errors Adjustments are done. To understand the method of adjustment, it is required to know the concept of vector geometry.

The Departures and Latitudes between 2 points are established. These calculations are done for each leg of the traverse until the Last station, and are tabulated. A Sample Sheet for an Open Traverse. Azimuth : These are the bearings of a Line at a point where the angles are measured From North and Clockwise.

These angles need to be calculated or recorded in order to compute the adjustments. Sum of the total Departures and Latitudes will give the Error in closure.Excel for Land Surveyors is a Hub for sharing helpful spreadsheet tools and applications to be used in the surveying field. Start a new discussion to share a spreadsheet with your fellow land surveyors!

Or simply respond to a discussion already created. I have prepared an excel spreadsheet for Traverse Corrections and Traverse Calculations, you can download the file from the bellow link. Sign Up Sign In. Excel For Land Surveyors.

Like 2. Like 1. Tags: closecorrectiontraversetraversingdownloadexcelspradshetsurveying. Email me when people reply — Follow. Kanan Protap Datta March 12, at am. How to download the excel file " Traverse Calculation excel sheet download ".

Traverse Calculation excel sheet download. Also I have described about T…. Monish K. Roopowa February 15, at am. Please send me the Traverse Calculation Excel sheet. I have to do a close traverse and have to do the computation. Ramendra Tiwari September 26, at am. This reply was deleted. Party Chief. Personal Introduction Started by chris correia in Other. Traverse Calculation excel sheet download Started by Soumen Samanta.

Note: this page contains paid content.The linear measurements are made with tape or chain, and the relative directions of the lines are measured with a compass, theodolite or Chain. Direction provides and measurement of distance the essential two-dimensional data for determining the land area and for delivering horizontal control. Traversing consists of reconnaissance selecting. A traverse, in general, is run to locate the features already existing in the area to be surveyed or to establish points or lines by predetermined measurements.

It is employed for surveying long narrow strips of country, e. A traverse is said to be a closed one if it returns to the starting point, thereby forming a closed polygon as per below polygon drawing. Also, a traverse which ends and begins at positions on the plan is known are also referred to as a closed traverse as per below trapezoidal drawing.

A closed traverse is employed for locating the boundaries of lakes and woods across which tie lines cannot be measured, for area determination, control for mapping.

Traverse Surveying: Adjustment of Closing Error

The linear measurements can be performed by any of the methods listed in the horizontal method. For ordinary surveying, chaining is perhaps the most common. The direction of the lines can be measured by the techniques discussed in Compass surveying and Theodolite. The precision usually specified for traversing requires the use of steel tape and the theodolite.

Also, read: Procedure for Rcc Concrete. No angle measuring instrument is used, and the directions of the lines are fixed entirely by liner measurements. Also, read: Lab Test on Aggregates at Site. Compass and chain traversing, the magnetic bearings of the lines of the survey are t the length of lines is measured either with tape or with a chain and measured by a compass. The direction of a magnetic meridian is established at each traverse station independently.

Types of Traverse in Surveying

The method is also known as free or lose needle method. A theodolite fitted with a compass may also be used for measuring the magnetic bearings of the traverse line. However, the method is not so accurate as of that of transit tape traversing. The methods of taking the details are almost the same as for chain surveying. Traversing is that types of the survey in which several connected survey lines form the directions, and the framework and lengths of the survey line are measured with the help of an angle or direction measuring instrument and tape or chain respectively.

It is known as a closed traverse When the lines form a circuit which ends at the starting point.A Traverse consists of a series of related points or stations, which when connected by angular and linear values form a framework. The Purpose of traverse surveys is to control subsequent detail, i. Fixing of specific points to which details can be related. The accuracy of the control survey must be superior to that of the subsidiary survey. When a series of connected lines form a closed circuit, i.

When the finishing point coincides with the starting point, then it is called a closed traverse. These closed traverse surveys have many applications like fixing the boundaries of ponds, forests, etc. Traverse Correction — Excel Solution.

Select the type of Traverse — Open or Closed. The corrected traverse, along with the detailed calculation table, based on the method selected for correction, will be displayed.

Software for Traverse Correction in CAD Package A Traverse consists of a series of related points or stations, which when connected by angular and linear values form a framework. Closed Traverse: When a series of connected lines form a closed circuit, i. To know more about Traverse Correction Procedure, Click the link below. Next, select the Polyline for which the Traverse correction has to be done. You need to specify at the command prompt, the calculation method of your choice.

Click a Point to create the Calculation details table. Phone Enter Valid Phone Number. Custom Payment Amount. Outside India Payments.Adjustment of a closed traverse includes: 1. Adjustment of Angular Error. Adjustment of Bearings. Adjustment of Closing Error.

The difference between the theoretic sum and the sum of the measured angles in a closed traverse is called the angular error of closure.

When all angles are measured with equal care and under similar conditions, this error is distributed equally among all the angles. However, if the accuracy of some angle or angles is suspected due to peculiar field conditions, the whole or the most of the angular error may be assigned to that angle or angles.

If traversing is done by taking bearings of the lines, the closing error in bearing may be determined by comparing the back and fore bearings of the last line of the closed traverse as observed at the first and last stations of the traverse respectively.

When the traverse ends on a line of known bearing, the error in bearing may be determined by finding the difference between its observed bearing and known bearing. If e is the closing error in bearing, and N is the number of the sides of the traverse, then the correction applied to the bearings of the sides are:.

While plotting a closed traverse, the end point coincides exactly with the starting point provided that work is correct.

Also in a closed traverse, the algebraic sum of the latitudes- the sum of northings-the sum of southings should equal zero, and the algebraic sum of the departures the sum of eastings — the sum of westings should equal zero. But due to errors in the field measurements of angles and distances, the traverse if plotted according to the field measurements will not close on the starting point.

The distance by which the end point of a survey fails to meet with the starting one is called the closing error or error of closure. In fig. Since the triangle A 1 A 2 A is right angled at A 2the linear closing error AA 1 is equal to the square root of the sum of the squares of the algebraic sum of the latitudes and that of the departures. It is process of adjusting the latitudes and departures by applying corrections to them in such a way that the algebraic sum of the latitudes, and that of the departures should each equal to zero, i.

adjustment of closing error by bowditch method

It is also known as the compass rule and is most commonly used in traverse adjustment. It is used when the angular and linear measurements are equally precise. By this rule, the total error in latitude and that in departure is distributed in proportion to the lengths of the sides.

This rule is used to balance the traverse when the angular measurement are more precise than the linear measurements.


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