1 Best Way To Solve Missing Entries In The Field Book In Levelling Survey

We will solve one of the major mistakes during the leveling survey. That is missing entries in the Field Book. I hope this blog post helps you. many people ask me how if we missed the entry of survey data in the field book we solve the calculation after the completion of the Levelling survey.

Table of content

What are the major data of the leveling survey?How to verify the data is accurate?What are the Missing Entries in the Field Book sample?How to calculate missing data?Airthematic Check

What are the major data of the leveling survey?

If you are a surveyor, I know you have the technical terms of the survey, like the Field book, Foresight, backsight, Reduced Level, and more.

If you are interested in individual technical survey terms you can check the previous posts on my website. I have mentioned all the terms used in the leveling survey.

During the leveling survey, You must have foresight, backsight, Intermediate sight, Rise, Fall, height of the instrument, and a Reduced level reading.

Without these readings leveling survey is not clear. But if you missed the cross-sign data at the filled book table, I will help you with that. How to calculate the missing entries in the Field Book.

How to verify the data is accurate?

The accurate and precise data is only one field data. So as possible, you don’t miss all the data during the leveling survey. But, in the leveling survey, You have one chance to verify the data is accurate.

You know Airthematic Check? After calculating the data from the field book you can verify the calculation by the airthematic check process.

Keep in mind the following formula for Airthematic check.

ΣBS-ΣFS=LRL – FRL=ΣRise-ΣFall

This is a simple and easy way to solve the missing entries in the Field Book data of the leveling survey.

What are the Missing Entries in the Field Book sample?

Now We have one sample of Missing entries in the field book. How to find that particular data? You can see below:

Station	BS	IS	FS	Rise	Fall	RL	Remarks
A	2.285					232.460	BM 1
B	1.650		x	0.020
C		2.105			x
D	x		1.960	x
E	2.050		1.925		0.300
F		x		x		232.255	BM 2
G	1.690		x	0.340
H	2.865		2.100		x
I			x	x		233.425	BM 3

Calculation of all Reduce Level and Missing data using the rise and fall method,

How to calculate missing data?

The following steps are the calculation part of this topic. By following the steps to calculate your missing data in the filed book. But on the list, you have given data in the filed book.

Foresight of station B (FS)=2.285-0.020=2.265 ( i.e BS-rise=FS)

Fall of station C (Fall)=1.650-2.105=-0.455 (i.e BS-IS=Fall)

Rise of Station D (Rise)=2.105-1.960=0.145

Backsight of station D (BS)= 1.925+(-0.300)=1.625

I hope you understand till here. Now we have one complicated issue. That is we don’t have two values of station F. We need two values i.e. IS and Rise of station F. For that, we need to Reduce the level (RL) of station E. If we have RL of E then we can easily find out the value of F station.

So let us find out the RL of station E. Using the Rise and fall method,

Station	BS	IS	FS	Rise	Fall	RL	Remarks
A	2.285					232.460	BM 1
B	1.650		2.265	0.020		*232.480*
C		2.105			*0.455*	*232.025*
D	*1.625*		1.960	0.145		*232.170*
E	2.050		1.925		0.300	231.870
F		x		x		232.255	BM 2
G	1.690		x	0.340
H	2.865		2.100		x
I			x	x		233.425	BM 3

Rise of Station F (Rise)=232.255-231.87=0.385

The intermediate sight of station F (IS)=2.050-0.385=1.665

Foresight of station G (FS)=1.665-0.340=1.325

Fall of Station H (fall)=1.325-2.100=-0.775

Again we need two values of station I. i.e. Foresight and Rise. Now we go to the Reduce level. we require a reduced level of station H for finding station I value.

Station	BS	IS	FS	Rise	Fall	RL	Remarks
A	2.285					232.460	BM 1
B	1.650		2.265	0.020
C		2.105			*0.455*
D	*1.625*		1.960	0.145
E	2.050		1.925		0.300
F		*1.665*		0.385		232.255	BM 2
G	1.690		*1.325*	0.340		232.595
H	2.865		2.100		*0.410*	232.185
I			x	x		233.425	BM 3

Rise of Station I (Rise)=233.425-231.820=1.605

Foresight of station I (FS)=2.865-1.605=1.260

Station	BS	IS	FS	Rise	Fall	RL	Remarks
A	2.285					232.460	BM 1
B	1.650		2.265	0.020
C		2.105			*0.455*
D	*1.625*		1.960	0.145
E	2.050		1.925		0.300
F		*1.665*		0.385		232.255	BM 2
G	1.690		*1.325*	0.340
H	2.865		2.100		*0.410*
I			*1.280*	1.585		233.425	BM 3

Summarize the answer

Following are the calculation of the required value and Reduced level of all stations.

Station	BS	IS	FS	Rise	Fall	RL	Remarks
A	2.285					232.460	BM 1
B	1.650		2.265	0.020		232.480
C		2.105			*0.455*	232.025
D	*1.625*		1.960	0.145		232.170
E	2.050		1.925		0.300	231.870
F		*1.665*		0.385		232.255	BM 2
G	1.690		*1.325*	0.340		232.595
H	2.865		2.100		*0.410*	232.185
I			*1.280*	1.585		233.770	BM 3

Airthematic Check

ΣBS-ΣFS=LRL – FRL=ΣRise-ΣFall

Formula,

ΣBS-ΣFS=12.165-10.855=1.31

LRL – FRL=233.770-232.46=1.31

ΣRise-ΣFall=2.475-1.165=1.31

Finally, our calculation is correct.

ΣBS-ΣFS=LRL – FRL=ΣRise-ΣFall (verified)

I am sure you are clear about this calculation. Don’t worry if you have missing leveling survey data due to different issues. If you have general data then you will be successfully calculated the missing entries in the field book.