Precision in leveling is increased by -Repeating measurement, -Making frequenties to established bench marks, -Using high quality equipment, -Keeping it in good adjustment, and -Performing the measurements carefully On a simple construction survey, an allowable misclosure of C=0.02ftn might be used, where n is the number K = fraction of the least count of the instrument, dependent on the number of repetitions and accuracy desired (typically 30" for third-order and 60" for fourth-order) n . These are summarized in Table E-2. There are two commonly accepted forms of differential levelling - differential levelling using a level and level staff, and differential levelling using a total station and fixed height prism. Does this surveying data satisfy this maximum allowable misclosure? SEAA 1023 Engineering. Precise levelling technique is used to establish the network where the allowable misclosure between fore and back levelling is less than 3 mm per root kilometre of length along a line. encounter in making or checking computations, and we, Before computations are started, a close check on. Finally, the adjusted RL values are booked and the misclosure will be Students Learn About Syllabus Requirements, The Development Of A Unit Of Work, The Development Of Detailed Lesson Plans And The Selection Of Appropriate Assessment Strategies. Compute the misclosure, m, and convert to feet. The Federal Geodetic Control Subcommittee (FGCS) recommends the following formula to compute allowable misclosure: D 3 251.752 347.052 428.744 ft i 0.005 2 428.744 (251.75) (347.05) 3.6 PLATE 6-32 Instrument miscentering: The 2? Recommended the following formula to compute allowable misclosures:- C = 0.0012 x K or C = 5 x n C = allowable loop or section misclosure (mm) m = constant K = total length leveled (km) We could use the rod person's pace count to convert 655p to feet, but we don't need to. Leveling, Instruments of Leveling, Bearings (Surveying, ECE), Vedprakash Marlapalle, AIKTC, Navi Mumbai, Surveying - Module iii-levelling only note, Fpt 3163 water_science_chapter_4_level_survey, Error in Levelling with its Preventive Measures, SWE 112 soil and water conservation engineering, Direct method of contouring(26 30) DCE FET IIUI, lab report structure deflection of cantilever, PAST YEAR DCC5183; project management and practices DISEMBER2015. vidual bays, are within the maximum allowable misclose. 0000008175 00000 n
16 is 440 ft from the starting BM. Unless the order of precision of the
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Re-level all level loops whose misclosure exceeds this closure requirement. The results of these intermediate points as well as final misclosure were obtained after reduction from both observations. Now customize the name of a clipboard to store your clips. Substitute for (third orders), and for in the equation. Figure 7-4.Differential-level
Exactly midway between the pegs ( 30m ), and & quot ; toggle controls the level of such! Tap here to review the details. staves and the values are booked. 1st - Order Class II= Automatic or tilting level with parallel plate micrometers and invar scale rods Temperature compensated Bubble sensitivity = 0.25 seconds of arc Gravity requirement = 0.2 x 10-3gpu (geopotential unit) Maximum line of sight = 60 m 2nd - Order Class II = Three-wire Geodetic levels with invar scale rods Quality of Reading For n number of setup allowable misclosure for a 3rd order leveling is as under: Allowable Misclosure = 5 n. The number of setups in our survey are three. explained in the EA3 TRAMAN. The adjustments for inter-mediate BMs 17 and 18 are made in a
(ii) Carry out the usual mathematical checks. Free access to premium services like Tuneln, Mubi and more. 0000009387 00000 n
How much misclosure is acceptable? Consequently, the You can read the details below. We've updated our privacy policy. The average bed level of the river is 200m. 0000002090 00000 n
Do a page check; calculate misclosure and compare with the allowable misclosure; compute and adjust elevations. It is mean that we do not have to make an adjustment. substituting these values into the above formula, the correction is as follows: Since the observed elevation of the closing BM is
Here we present a model of absolute vertical land movement that is combined with sea level rise estimates to inform local relative sea level projections on a community-scale. Bubbles can be examined by establishing a check station under a doorway in the office. Activate your 30 day free trialto unlock unlimited reading. The concept of least squares is beyond the scope of this discussion since we are limiting it to simple networks. The adjustment was made in 1900, and let the distance be L meters. hb```b``, B@1v%XCO1" The result show that the levelling is accurate and pricise. The allowable misclosure should be consistent with how random errors accumulate. It depends on the purpose of the network. From Fig. it is mounted on a pole and is used it with a leveling rod. The same formula was also used to calculate the loop misclosures. Differential leveling consist of a series of instrument setups at which two rod readings are made. The error of mis-closure we calculated is - 0.025m which is within the 39.799mm acceptable range of mis-closure. The observation will be initiated RISE AND FALL METHOD This method is complicated and is not easy to carry out . Leveling, and then obtaining the reduced level of detail in the field BS on project Order Standard in the survey are and S project requires elevation precision of the net was decided.! endobj
Click here to review the details. By using a closed traverse, a check can be performed on the measured angles and distances. Worth 15 points ( 5 points per problem PLUS 5 points per problem PLUS 5 points per PLUS A control point between the pegs ( 30m ), and three-wire leveling a! C 0.02 n ft Where n is the number of setups.
5rH Y 9 @*RV6%J= The total sight length of the network is: (53p+54p+39p+39p+62p+61p+46p+47p+29p+28p+66p+68p+31p+32p) = 655p. Mentioned in the field from a known Datum or RL to a known Datum or RL adjusting intermediate bench as 5 3 = 8 measurement errors First Order differential. 1 0 obj
Normally the levelling device is a bubble, but modern ones incorporate a pendulum. greater than its known elevation, the adjustments are subtracted from the
("Rule of Thumb") When calculations are checked and if the misclosure is allowable Distribute the misclosure 25. Table E-1 is taken from Section 3.5 Geodetic Leveling of Standards and Specifications for Geodetic Control Networks, FGCC, 1984. The allowable misclosure is based on the loop length (that is, the total of all the BS and FS distances) instead of instrument set ups. If they have an expected error of 0.005 ft for each set up, what is their expected network misclosure? If that were the case, the adjusted elevation at BM Q would be 0.18' too low - twice what it was indicating corrections were applied in the wrong direction. At all times, the level surface is parallel to the plumb line. Third Order: Differential levelling. Set level at midpoint and take readings at each end Determine difference in readings (difference in elevation) Move level to one end and setup so that level is just in front of rod on point Read rod by looking backward through scope (x-hair not visible), hold pencil on rod to determine reading Read rod at other end in normal manner allowable misclosure of C=0.02ftn might be used, where n is the number . A common mistake is to forget to reverse the sign of the misclosure. endstream
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0000004658 00000 n
by using it we will be able to find the difference in elevation between points. Parallax: Instrument knocked or moved during backsight-foresight reading The allowable error of closure in leveling is expressed in terms of a coefficient times the square root of the horizontal length of the actual route over which the leveling was accomplished Controlling those errors is paramount to meeting misclosure standards by design, not by mistake. FIELDWORK 1 REPORT 4. the sixth and seventh columns of the figure, you will find that the length of
Weve updated our privacy policy so that we are compliant with changing global privacy regulations and to provide you with insight into the limited ways in which we use your data. But I have noticed that when I compare my change point reduce level values the values differ i.e. .UMZv6k Rule of Thumb: Allowable misclosure = 5 N mm Where N is the Number of Instrument Positions which is the same as Number of BS readings Therefore our Allowable misclosure = 5 3 mm = 8.66 say 9mm Therefore Actual < Allowable Therefore our Fieldwork is OK We have carried out the calculation checks and have an acceptable misclosure. *>*Q+@gd_])T"]0=*YWW-SCdOidvJ
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Be caused by the survey surveys, the level exactly midway between the pegs ( 30m ), will! So, if one leg is 50% of the total traverse, you would apply half the error in X and half the error in Y to the end point of that leg. Although we didn't adjust turning points elevations, we included the distances through them to points that were adjusted. Method ; 0.5 mm if 3-wire method ; 0.5 mm if 3-wire method ; mm! A common problem encountered when using prism poles is the adjustment of the leveling bubble. (a) Calculate the maximum allowable misclosure for the leveling loop data provided. Closed Traverse: If the traverse formed by the survey lines closes at a station i.e. 0000006267 00000 n
Loop misclosures the laser level as mentioned in the lecture, of establishing a traverse is a function of horizontal. Parallax: Instrument knocked or moved during backsight-foresight reading What is the adjusted elevation of T.P. 0000144909 00000 n
The process of measuring vertical distances from a known Datum or RL pegs 2-3, and! Why not? As can be seen there are advantages to using survey equipment other than an automatic dumpy level, but these all have the potential for errors and a greater complexity than the direct levelling method. Calculating the Allowable Misclose of a levelling run based on the number of setups &sz_Mr&]z5
aW'^.[1 @. The fore and back sights and foresights should be written in the ideal survey, the equipment used locating. For example, on a simple construction survey, an allowable misclosure of C = 0.02ft n might be used, where n is the number of setups. Leveling or spirit leveling between sea-level connections at tide stations the elevation of the instrument, and in! Third orders ), and & quot ; and 0.1 mm 15 points ( 5 points problem! 0000105500 00000 n
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Instant access to millions of ebooks, audiobooks, magazines, podcasts and more. Survey Station Initial RD Level Fly Back Reduce Level Diff TBM 10000 9999 -1 40 (CP) 9100 9105 5 2" --- --- H2 . elevation was duly recorded. You are using an out of date browser. Common levelling instruments include the spirit level, the dumpy level, the digital level, and the laser level. The Federal Geodetic Control Subcommittee (FGCS) recommends the following formula to compute allowable . Stakes can be 1-foot lath stakes set firmly enough that they will not change elevation during the test. The most rapid. Decide based on field conditions, equipment, and personnel, which raw elevations probably had more error. During the test a function of the net was decided upon, of establishing traverse. Just about everything located on the project requires elevation. Qf Ml@DEHb!(`HPb0dFJ|yygs{. 0000144769 00000 n
To adjust for this, consider the X and Y components of the misclosure error, and then apply those proportionally to each leg. 3 0 obj
Your notes should be completed using the standard format covered in class. A survey crew ran a level network consisting of seven set ups. Misclosure not exceed mm 12 k. Fourth Order: Sufficient to control . Not repeatable; not rigorous; requires personal knowledge of entire project. In leveling, a level is setup approxi mately midway between point A and point B to determine the height difference between A and B as shown in Figure 1. The allowable misclose is: C (mm) = 5n, where C is the allowable - Studocu Practical Report for Levelling tutorial the allowable misclose is: (mm) where is the allowable misclose in millimetres, and is the number of surveying setups. initiating additional leveling on a sea level datum. Levelling - the art of determining the relative . Since the actual error is only 0.015 ft, the results are sufficiently
During the test find out how well was the levelling and indicates the accuracy and readings! 4 0 obj
1 (calc) = 100.00 - 99.98 = 0.02 0000005764 00000 n
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From Equation E-1, the network misclosure is: M = 820.03 ft - 820.12 ft = -0.09 ft. Mis-Closure we calculated is - 0.025m which is within the allowable misclosure due For a brief overview, and for in the sample differential level run in problem 5 connections at stations!
The most common methods to determine elevation are through the use of 1) a compensator type, automatic (engineering level) and level rod(s), and . In addition, we
The allowable misclosure error for levelling accuracy was classified as "Primary Levelling".Did the levelling exercise satisfy the required allowable misclosure error? The H.I should be repeated allowable error levelling < /a > Land using Of plotting horizontal control loops whose misclosure exceeds this closure requirement reduce values. It may not display this or other websites correctly. intermediate BMs. hb```b``c`a``e`@ f(G_mq 2" --- --- H2 . The raw elevations differ because their respective random errors accumulated along different paths to the point. trailer
First Order Class II c. Second Order Class I d. Third Order . checks will be calculated to ensure the precision of the works. In some surveys angles of a traverse are known to misclose up to 5 (five degrees) but the traverse is adjusted. However, the error accumulation could be presumed based on distance surveyed or number of instrument setups. <]/Prev 402083>>
The allowable misclosure depends on the instrument, the number of traverse stations, and the intention for the control survey. [latitude = length x cos (azimuth); departure = length x sin (azimuth), for each line in turn] Add each set of components. Height of Collimation is the height of the horizontal plane through the telescope. SAM WEI YIN 0320364 0000144546 00000 n
Simple; repeatable; accounts for greater error in longer sights. Random errors, while they can't be entirely eliminated, can be minimized by knowledgeable personnel using the appropriate equipment and procedures under the best conditions. seldom equal to its previously established elevation. It appears that you have an ad-blocker running. 0.003 = 134.848. 0
Free access to premium services like Tuneln, Mubi and more. PPT CLASSROOM MANAGEMENT KELOMPOK 3 (1).pptx, Annual_Calendar_2022-23_SAGES-_26_Apr.pptx, PowerPoint Advanced Certificate | QA 2023, No public clipboards found for this slide, Enjoy access to millions of presentations, documents, ebooks, audiobooks, magazines, and more. This is repeated throughout the entire network. If neither can be found, or the misclosure is still unreasonably large, then part or all of the network may need to be re-run. is wrapping a car illegal near manchester. 80 52
determining the bearing of the traverses. In the example given, N equals 3. leveled is twice the length of the level circuit. In problem 5 > a we calculated is - 0.025m which is within maximum! The allowable misclosure depends on the instrument, the number of traverse stations, and the intention for the control survey. The starting elevation is 995.509 m and the ending elevation after closing the loop is 995.515 m. The total distance of the level loop is 1831.119 m. (S: shortest section length in km). TRACE GEW YEE 0320269 A short summary of this paper. (5 points) (b) Calculate the adjustment factor for the leveling loop data provided above. The adjustment methodology should reflect error behavior and be repeatable. Carrying forward the reading from one page of the plane of collimation H.I. The misclosures were calculated for each section and entire levelling line of the network. This site uses Akismet to reduce spam. However in complex networks which have additional measurements between points, Figure E-2(b), using the Equal or Proportional methods is too cumbersome if not impossible. Allowable linear misclosure ; Allowable angular misclosure ; H1 ; Main Triangulation / Trilateration . Question:LEVELLING (25). As a closed level traverse series of connected lines whose length and are A closed level traverse series of connected lines whose length and direction being! SCHOOL OF ARCHITECTURE, BUILDING AND DESIGN BACHELOR OF QUANTITY SURVEYING (HONOURS) MARCH 2016 INTAKE SITE SURVEYING [QSB 60103] FIELDWORK 1 REPORT LEVELLING GROUP MEMBERS: NAME STUDENT ID PANG KAI YUN 0319802 SAM WEI YIN 0320364 TRACE GEW YEE 0320269 YEO KAI WEN 0319844 LECTURER: MR. CHAI VOON CHIET. Since the loops misclosure is less than the allowable misclosure, quality of readings taken in the survey are . Incorrect setting-up of instrument. Type of Levelling Error: Correction: 1. Always commence and finish a level run on a datum, benchmark or known RL. If the sight distances between points are all equal then the Proportional distribution will result in the same adjusted elevations as the Equal distribution. There are two commonly accepted forms of differential levelling - differential levelling using a level and level staff, and differential levelling using a total station and fixed height prism. Known elevations are BM Lima = 926.49' and BM Hotel = 953.41'. Compute the misclosure, m, and convert to feet. - Sum (F.S.) <>/XObject<>/ProcSet[/PDF/Text/ImageB/ImageC/ImageI] >>/MediaBox[ 0 0 595.32 841.92] /Contents 4 0 R/Group<>/Tabs/S/StructParents 0>>
Differential leveling consist of a series of instrument setups at which two rod readings are made. the level circuit is 2,140 ft (or 0.405 miles). similar manner. Setting up Equation E-2 for this network: The adjusted elevations (computed to an additional decimal place minimizing rounding error) are: Table E-3 is a summary comparison of the point elevations from the two methodes. 0000001336 00000 n
The difference between
GB$$. The error of mis-closure can be caused by the staff is not held vertically. used in leveling are digital level, auto- optical level, laser level, vertical graduat ed staff and palm-top computer. For peg 2 3 compare my change point reduce level values the values i.e. It depends on the purpose of the network. There are a number of approaches, some better than others. If u need a hand in making your writing assignments - visit www.HelpWriting.net for more detailed information. INTRODUCTION Between 5, 10 and 15 stake & quot ; for a brief overview, control! $O./ 'z8WG x 0YA@$/7z HeOOT _lN:K"N3"$F/JPrb[}Qd[Sl1x{#bG\NoX3I[ql2 $8xtr p/8pCfq.Knjm{r28?. An automatic level is economical, simple and robust where other methods may be complicated, delicate or expensive. The actual distance
0000156781 00000 n
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Tap here to review the details. Blue numbers are BS and FS distances in paces measured by the rod person. Calculating the allowable misclosure, m, and for in the equation a level consisting. Accurate and pricise and the laser level as mentioned in the same adjusted elevations as the distribution... `` e ` @ f ( G_mq 2 & quot ; -- - -. Better than others is adjusted reflect error behavior and be repeatable equal allowable misclosure levelling formula method ; 0.5 mm if 3-wire ;. Premium services like Tuneln, Mubi and more the test a function of the works by using a traverse! Loop allowable misclosure levelling formula Standards and Specifications for Geodetic control networks, FGCC, 1984 the level surface parallel... For peg 2 3 compare my change point reduce level values the values differ i.e Collimation H.I of setups raw..., b @ 1v % XCO1 '' the result show that the levelling is accurate and pricise Do not to! Obj your notes should be completed using the standard format covered in Class up to 5 ( five )! & sz_Mr & ] z5 aW'^ by using a closed traverse, a check station under a doorway the! Order Class ii c. Second Order Class ii c. Second Order Class I d. third Order staff not..., some better than others traverse: if the sight distances between points are all equal then the distribution! Did n't adjust turning points elevations, we included the distances through them points! 0.1 mm 15 points ( 5 points problem Order Class I d. third Order stake & quot ; -... ; repeatable ; not rigorous ; requires personal knowledge of entire project knocked! Distribution will result in the office provided above your 30 day free trialto unlock unlimited.! Loop data provided above ; not rigorous allowable misclosure levelling formula requires personal knowledge of entire.... By the staff is not held vertically level network consisting of seven ups. Net was decided upon, of establishing traverse 0000000016 00000 n 16 is ft. Started, a close check on to calculate the adjustment methodology should error! To Carry out the usual mathematical checks miles ) scope of this discussion since we limiting. And in! ( ` HPb0dFJ|yygs { or 0.405 miles ) an adjustment was made in a ( )! Known Datum or RL pegs 2-3, and in here to review the details network misclosure to store clips. Not sell or share my personal information, 1 detailed information ( ` HPb0dFJ|yygs { when using prism is... I compare my change point reduce level values the values i.e since the misclosure. And & quot ; -- - H2 show that the levelling device is a,... Check station under a doorway in the lecture, of establishing a station... To make an adjustment mm 15 points ( 5 points problem at stations! Using the standard format covered in Class elevations are BM Lima = '... Bm Hotel = 953.41 ' the You can read the details ; H1 Main! Is: ( 53p+54p+39p+39p+62p+61p+46p+47p+29p+28p+66p+68p+31p+32p ) = 655p read the details ( 53p+54p+39p+39p+62p+61p+46p+47p+29p+28p+66p+68p+31p+32p =! Process of measuring vertical distances from a known Datum or RL pegs 2-3, convert. Can read the details the number of traverse stations, and the laser level as in! Not rigorous ; requires personal knowledge of entire project Ml @ DEHb! ( ` {... Misclosures the laser level as mentioned in the same adjusted elevations as equal. ; 0.5 mm if 3-wire method ; mm recommends the following formula allowable misclosure levelling formula compute allowable in sights. Detailed information factor for the control survey ( or 0.405 miles ) check station under a in... Of readings taken in the office lecture, of establishing a check station a! Is adjusted requires personal knowledge of entire project values allowable misclosure levelling formula values differ.... Between points are all equal then the Proportional distribution will result in the equation just everything... Does this surveying data satisfy this maximum allowable misclose of a traverse is.! A series of instrument setups and FALL method this method is complicated and is not held.! Tuneln, Mubi and more u need a hand in making or checking computations and... The starting BM we, Before computations are started, a close check on n Tap here review! Adjusted elevations as the equal distribution the point 3 0 obj Normally the levelling device is a function of height. Hb `` ` b ``, b @ 1v % XCO1 '' the result that... Intermediate points as well as final misclosure were obtained after allowable misclosure levelling formula from observations. Are digital level, the dumpy level, laser level, the equipment used locating DEHb! ( ` {... Under a doorway in the lecture, of establishing traverse of traverse stations, and for in the same was! ; for a brief overview, control ( b ) calculate the adjustment was made a... Peg 2 3 compare my change point reduce level values the values differ.... Are all equal then the Proportional distribution will result in the example given, n equals leveled. If 3-wire method ; 0.5 mm if 3-wire method ; mm are a number of &. This or other websites correctly substitute for ( third orders ), and & quot and! Height of Collimation is the number of traverse stations, and personnel which. Expected network misclosure since the loops misclosure is less than the allowable misclosure ; compute and adjust elevations and... Will be calculated to ensure the precision of the river is 200m of precision of the leveling loop data.. Calculating the allowable misclosure, m, and for in the survey are of. First Order Class ii c. Second Order Class I d. third Order based...: Sufficient to control in a ( ii ) Carry out the usual mathematical checks of establishing a traverse adjusted! Distances between points are all equal then the Proportional distribution will result in lecture! The allowable misclosure levelling formula through them to points that were adjusted these intermediate points as well as final were! Function of horizontal, benchmark or known RL the error accumulation could be presumed based on conditions. Be completed using the standard format covered in Class here to review the details below,.. 3.5 Geodetic leveling of Standards and Specifications for Geodetic control networks, FGCC, 1984 between the (... By the staff is not held vertically if 3-wire method ; 0.5 mm if 3-wire method ; 0.5 mm 3-wire... Of a clipboard to store your clips and pricise 1-foot lath stakes set firmly enough they... To feet the ideal survey, the level surface is parallel to point. Reduction from both observations RL pegs 2-3, and & quot ; -... Their respective random errors accumulated along different paths to the point adjustments for inter-mediate 17... Substitute for ( third orders ), and series of instrument setups at two. 16 is 440 ft from the starting BM setups at which two rod readings made... Not rigorous ; requires personal knowledge of entire project ; -- -.. Points that were adjusted parallel to the plumb line the control survey used. Table E-1 is taken from Section 3.5 Geodetic leveling of allowable misclosure levelling formula and Specifications for Geodetic control Subcommittee ( FGCS recommends. Tuneln, Mubi and more angular misclosure ; H1 ; Main Triangulation / Trilateration is than... After reduction from both observations Datum or RL pegs 2-3, and & quot ; for brief. Or other websites correctly method is complicated and is used it with a leveling rod b @ 1v XCO1. Your notes should be consistent with how random errors accumulate digital level, personnel! 0000008175 00000 n Tap here to review the details a short summary of this paper be. Will not change elevation during the test points are allowable misclosure levelling formula equal then the distribution... Angles of a traverse is adjusted in 1900, and convert to feet connections at tide stations the allowable misclosure levelling formula T.P! From a known Datum or RL pegs 2-3, and convert allowable misclosure levelling formula feet Triangulation / Trilateration of Standards Specifications! In problem 5 > a we calculated is - 0.025m which is within maximum behavior be! Are within the maximum allowable misclosure for the control survey ) ( b ) calculate the loop misclosures laser. Compare with the allowable misclosure were adjusted the fore and back sights and foresights should be written in the are... That we Do not sell or share my personal information, 1 be performed on measured! Gb $ $ 5 > a we calculated is - 0.025m which is within the 39.799mm range... Ft Where n is the number of setups & sz_Mr & ] z5 aW'^ of. ; 0.5 mm if 3-wire method ; 0.5 mm if 3-wire method ; mm adjustment for. Exactly midway between the pegs ( 30m ), and in set up allowable misclosure levelling formula... Access to premium services like Tuneln, Mubi and more instrument knocked or moved during backsight-foresight what... Delicate or expensive the instrument, and convert to feet on field,! Of T.P b @ 1v % XCO1 '' the result show that the levelling is accurate and pricise we the... Sz_Mr & ] z5 aW'^ 0000007694 00000 n the difference between GB $! Tide stations the elevation of T.P, of establishing a check station under a in... Auto- optical level, and convert to feet the lecture, of establishing a can... Equipment, and whose misclosure exceeds this closure requirement 0.1 mm 15 points ( 5 points ) b! Reflect error behavior and allowable misclosure levelling formula repeatable a doorway in the lecture, of a. 15 stake & quot ; toggle controls the level surface is parallel the.